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Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis and Dissertation Collection 1987 Design and implementation of a fiber optic RS232 link. Ryan, James William. http://hdl.handle.net/10945/22233 DOT; Ni M0; ^M rI00L „~, RNIA 95943-5002 NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS DESIGN AND IMPLEMENTATION OF A FIBER OPTIC RS232 LINK by James William Ryan September 1987 Thesis Advisor: John Approved for public release; distribution Powers P. is. unlimited T 23437 ?jri^FT7riTTTT7TT^r7^rT^r77^r REPORT DOCUMENTATION PAGE R£S T R"CTlVE ID fW"!.S£CLL',i T_? CuftSS'f'CATiON i* MARKINGS UNCLASSIF] i* S#CU*» |T ClASS^lCATlON AO»hO«iI» Approved for public release; distribution is unlimited 4 JtafCau.NO Organisation «(PO«f nuM8(»()| MVt I 0' Pf bo o*mce symbol HfOOM'NG ORGANISATION *OQ*fSS >Of> Hit*. *nd MON.rO«'NG ORGANISATION REPORT NUVB£«(S; S daval Postgraduate School b* '•'Naval 62 /i? Cod*) Sr«f r *"0 O^ MONiTOR'NG ORGANISATION Postgraduate School A0D9£SS;Ory SUM, 7b OP Coo*) *r<l Monterey, California 93943-5000 80 0»HC£ SYMBOL HA*rt O* »UNOiNG. SPONSORING C*CAN.»'-ATiON ACQ^SSfCify NAW( ;j Monterey, California 93943-5000 »e OlSIBiBuTlON/ AVAHAgitlTY 0» REPORT SOtOULE 0*i.t*SS-*'<-A''-ON'0O*VNG«A0iNO ^O J PROCUREMENT INSTRUMENT 9 iO£ N r.fiCA TiON NuM9£R 0* *(xH«4bt*> /" CotfvJ 10 SOURCE O* fuNOiNG NUMBERS PROGRAM PROJECT TAS< WORK ELEMENT NO NO NO ACCESSION jNiT Design and Implementation of a Fiber Optic RS232 Link •: f«SONA <aster's •» k AuT«OR(S) Ryan, James W. i Thesis Jo t.m£ COvEREO »OQM Month D*y) 93 W*-.1V{NTAR» NOTATION COSATi COOES * 9 t9*f "M'SepSfcS r TO GROUP ElO Aisr^^r (Conf>n u * '8 SuBGROL'P on rtvtn* it Su8jECT t £RMS (Conlinvt 0» 'r»*r|# it nttfUtry *nd tdtnl.ty by ©/Of* n««a»') Fiber Optics, RS232, Optical Link n#(«ij4/> *n«j a^ntity by 6">» n u mo*r) This thesis investigates the feasibility of using a bidirectional fiber optic link to implement a RS232 data link. The results showed that a fiber optic link is a viable replacement. It offers. a bandwidth up to 5 MHz, 250 times that of a RS232 data link. This fiber optic link was implemented over a distance of 1.5 kilometers, nearly 100 times that of the present RS232 link. It also offers the benefits of space and weight savings and is comparable to devices produced commercially but at a substantial cost savings. S"»*SuT'ON. AVAiLAiiiiTr O* ABSTRACT P^VCiAtSiHEO'uNi'MiTEO | %AM| o* D 2\ SAME AS RPT D ABSTRACT SECURITY CUASSiUCAHON UNCLASSIFIED QTiC uSERS RESPONSIBLE 'NO'ViOuai. 210 TELEPHONE John P. Powers (ln<lu<3f ArfsCo&f) 22(. OMicE SrMBOl 408-646-2200 SKu«' T All <>»«•' »OM.O«1 *'• OblOI«t« 1 * CLASSIC at. Qn Q( '-'S o±Zl NO Approved for public release; distribution is unlimited Design and Implementation of a Fiber Optic RS232 Link by James William Ryan Lieutenant, United States Navy B.S., Salem State College, 1981 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN ELECTRICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL September 1987 ABSTRACT This thesis investigates the feasibility of using a bi- directional fiber optic link to implement a RS232 data link. The results showed that a fiber optic link is a viable replacement. It offers a bandwidth up to 5 MHz, 250 times that of a RS232 data link. This fiber optic link was implemented over a distance of 1.5 kilometers, nearly 100 times that of the present RS232 link. It also offers the benefits of space and weight savings and is comparable to devices produced commercially but at a substantial cost savings. 5<5 TABLE OF CONTENTS I II III . . . IV. V. INTRODUCTION 9 A. PURPOSE 9 B. RESULTS 10 BACKGROUND 12 A. THE RS232 INTERFACE 12 B. PROPOSED FIBER OPTIC LINK 15 IMPLEMENTED FIBER OPTIC LINK 20 A. CROSS CONNECTIONS OF THE RS232 20 B. TRANSMISSION OF THE LIGHT SIGNAL 27 C. RECEPTION OF THE LIGHT SIGNAL 32 D. RECEIVER MODIFICATIONS 34 SYSTEM EVALUATION 37 A. TRANSMITTED OPTICAL POWER 37 B. OPERATING WAVELENGTHS 38 C. RECEIVER SENSITIVITY LEVELS 39 D. CROSSTALK 39 E. TRANSMITTED AND RECEIVED SIGNALS 46 F. LINK DISTANCES 72 G PRODUCT COMPARISON 73 CONCLUSIONS APPENDIX A: : MOTOROLA MC1489 QUAD LINE RECEIVER DATA SHEETS 75 76 APPENDIX APPENDIX B: C: RCA LINEAR INTEGRATED CIRCUIT CA3127E HIGH FREQUENCY N-P-N TRANSISTOR ARRAY DATA SHEETS 81 MOTOROLA MC1488 QUAD LINE DRIVER DATA SHEETS 84 LIST OF REFERENCES 90 INITIAL DISTRIBUTION LIST 92 LIST OF TABLES I. II III IV. V. VI EIA RS232 STANDARDS 14 HP-85 RS232 PINS 21 NEC RS232 PINS 22 AMPEX RS232 PINS 23 APPLIED AND RECEIVED SIGNALS 50 PRODUCT COMPARISON 74 LIST OF FIGURES 1. Light Transmission Scheme 11 2 . CAF 17 2 . Fiber Optic Module 18 3 . HP-85 / NEC Connection 24 3 . HP-85 / AMPEX Connection 25 3.3 HP-85 RS232 Voltage Levels 28 3.4 NEC RS232 Voltage Levels 29 3 Transmitter 31 . 3.6 Receiver 3.7 System Diagram 35 4 . Applied 1 MHz Signal 41 4 . Unshielded Circuitry. - Crosstalk 42 4 . Shielded Circuitry - Crosstalk 43 4.4 Unshielded Circuitry With CAF - Crosstalk 44 4.5 Shielded Circuitry With CAF - Crosstalk 45 4.6 HP-85 NEC Signals 47 4.7 HP-85 AMPEX Signals... 48 4.8 1 Hz Applied Signal 4.9 1 Hz Signal After .33 3 51 Meters Hz Signal After 1511 Meters 4 . 10 1 4 . 11 100 Hz Applied Signal 4 . 12 100 Hz Signal After 3 53 54 55 Meters 56 4.13 100 Hz Signal After 1511 Meters. 4 . 14 1 KHz Applied Signal 4 . 15 1 KHz Signal After 4.16 1 KHz Signal After 1511 Meters 58 . Meters 3 4 . 17 10 KHz Applied Signal 4 . 18 10 KHz Signal After 4 . 19 10 KHz Signal After 1511 Meters 3 59 60 61 62 Meters 63 65 4.20 1 MHz Applied Signal 4.21 1 MHz Signal After 4.22 1 MHz Signal After 1511 "Meters 68 4.23 5 MHz Applied Signal 69 4.24 5 MHz Signal After 4.25 5 MHz Signal After 1511 Meters 3 3 66 Meters Meters 8 67 70 71 I. INTRODUCTION This thesis investigates replacing the RS232 electronic link with a fiber optic link. The primary objectives were an investigation of the practical problems associated with connecting two noncompatible devices together and then to implement these connections onto a fiber optic link. m A. PURPOSE The. implementation of a fiber optic link offers several distinct advantages over an electrical one. First the fiber and the supporting circuitry would require less space and would weigh less than an electronic link. The increased bandwidth offered by a fiber optic link would offer the user the possibility of system expansion. Utilizing fibers would virtually eliminate the problem of crosstalk which can occur when two wires are close enough to each other to allow signals from one line to cross over to another as a result of electromagnetic interference (EMI) . [Ref . 1] The fiber optic link proposed here is full duplex bidirectional over a single fiber. The link achieves this capability by utilizing a wavelength division multiplexing scheme. In wavelength division multiplexing several optical signals of differing wavelengths are coupled into a single fiber [Ref. 2] Wavelength division multiplexing is achieved in this project through the use of a dichroic filter. As seen in Figure 1.1 a dichroic filter allows the transmission of one wavelength while reflecting the other wavelength. Specifically, a light wave, generated by an LED, transmits through the filter and is directed into the fiber optic cable. A light wave, which is generated in the same fashion at the other end of the fiber, reflects off of the dichroic filter and into a PIN detector. A complete ana-lysis of light generation and reception is found in Chapter III. B. RESULTS The researched showed that the link investigated in this thesis is realizable and it was found to be comparable to units on the commercial market. A detailed analysis of the system performance is found in Chapter IV. 10 m Q) g 0) <D o 03 c o w •H W •H 6 en c P .C tP 5 UJ > UJ a •H vi 0) 11 II. A. BACKGROUND THE RS232 INTERFACE In order for two devices to communicate, they must be connected in such a way so that electrical signals are trans- mitted and received correctly by each unit. This connection may be achieved directly by connecting wires to the devices or by using an intermediate medium. More often than not, the telephone network is used as this medium. The most widely used connection to link the medium to the device is the RS232 data link. [Ref. 4:p.l67] The RS232 link was originally designed to allow communi- cations between data terminal equipment (DTE) (i.e., computers) and data communication equipment (DCE) modems) [Ref. 5:p. (e.g., 11]. For the application discussed in this project two DTEs will be connected without the use of DCEs. This configuration is called null modem [Ref. 5:p. 13]. When this is done, a problem often arises. The DTEs cannot communicate with each other as the pin configurations of the RS232 were designed to be connected to DCEs. It would seem as if all one would have to do is cross-connect the pins. However this is not the case, as the manufacturers designate the pins of the RS232 to suit their own needs. To find these 12 cross-connections required is sometimes a very frustrating and time consuming venture. In an effort to make equipment from different man- ufacturers compatible the Electronic Industries Association, (EIA) , published a standard, the RS232-C. Unfortunately this standard specifies the connections between DTEs and DCEs. Specifically it delineates the electrical characteristics of the circuits between the two devices and the names and numbers of the pins necessary for connection to allow communications. The pins numbers and titles as specified by the EIA are listed in Table I. Since this project is concerned only with null modem configurations, not all the pins listed will be discussed in this project. While the RS232 link is an extremely useful interface it has an potential ground loop problem. Because of this and other prob-lems, the standard recommends that the cable interconnection between the two devices should be limited to a maximum dis-tance of 50 feet; at longer distances the connection becomes unreliable and hazardous. [Ref. 4: p. 168] Another major problem with the use of the RS232 is that large signal voltages are required to insure noise immunity is achieved on the link. The RS232 signal voltages are anywhere between plus and minus 25 volts. These high transmission voltages are required because of common mode noise. This noise could be on the level of a few volts. Some of the sources of the common mode noise could be from photocopiers, typewriters, 13 source) source) (DCE source) source) ' (DTE detector (DCE w Q timing c o (DTE/DCE timing signal return) timing data 9 detector o element testing) testing) send i/i 00 data a line send set selector to set element H W cn < E- Eh CO to signal data element detector (common signal a transmitted ready data request received received ground data •• rate clear send signal signal for for data CI cn r* send to quality line indicator terminal signal to Transmitted Transmission set (Reserved Protective Received (Reierved Secondary Request Unassigned Unassigned Unassigned w Secondary Secondary Secondary Secondary Clear '5 E O Data Data Ring UOu. 00 < < <O0DUU << a) Signal Data CO u. 00 I I 1 1 <m 03 * IO "* WWW Q n O u Ul < § 1 e § 3 c c »- c« « •» »o 10 r« a 0) »- <s c 14 in MS O) <4-l Transmit Receiver Received Signal « w ground ready O r- «n <•> v rf) printers, etc. Even if a link of greater than 50 feet could be safely achieved, one would find that a build up of capacitance is present, which would severely affect the quality of the signal as it transitions between the positive and negative voltages. [Ref. 5: p. 14] Another limiting feature of the RS232 interface is that, even with these high voltage levels that the EIA standard specifies the interface is rated for a signaling rate from d.c. to an upper limits of only 20K bits per second. [Ref . 6:p. 79] B. PROPOSED FIBER OPTIC LINK The proposed fiber optic link presented in this project would eliminate problems inherent in the RS232 link. This link would increase the distances between DTEs almost 100 fold and increase bandwidth to "that of 250 times to that of the RS232. The applications for a link such as this one are numerous. It opens the possibility of data transfer simplification, weight reduction of the link, communications link security, and the expansion to a LAN (local area network) The link described here is full duplex over a single fiber. In a full duplex mode both DTEs can be transmitting simultaneously. In other fiber optic links simultaneous transmission was only possible by using two fibers, one for transmission and one for reception. To achieve a single fiber scheme the two light signals must be multiplexed onto one 15 fiber. The multiplexing method used for this link is wave- length division multiplexing (WDM) WDM is obtained through the use of a coupler manufactured by ADC FIBER OPTICS. This coupler is called a Connectorized Active Full Duplex Coupler (CAF) [Ref. 7:p. 1]. A diagram of the operation of this coupler is shown in Figure 2.1. As can seen there are two LEDs transmitting at two differing wavelengths. The light signal transmitting at 865 nanometers will be detailed as an example as the transmission and reception of the other wavelength of 730 nanometers is similar. The electronic signal generated by the DTE is converted to a light signal by the 865 nanometer LED, (a detailed analysis of this process is found in chapter 3) , the light wave passes through a dichroic filter, which passes that wavelength, and is reflected into the fiber by a focusing mirror. As the light exits the fiber at the other end it is incident upon another focusing mirror which directs the light wave onto another dichroic filter. This dichroic filter is set to transmit the light 730 nanometer causing the light at 865 nanometers to be reflected into the PIN detector. From the detector the light wave is converted to an electrical signal. The CAF described above is an integral element of the fiber optic modules used in this link; a diagram of these modules is shown in Figure 2.2. The three major components of are: the transmitting circuitry, the receiver circuitry and the CAF. The basic operation for the modules is that the 16 in •• En < £ Z<* to 00 cc LU UJ w m u. <U / •H CM o I c X o X o u. < LU z z o o • En / C_ v„ > ° >"- • /\ 17 n d) a) 3 a o u 0) X! CM a) •H 18 incoming electrical signal drives current through the LED in the CAF, sending a light wave into fiber which is received by the PIN detector in the other CAF. The light wave is converted to an electrical signal and through the use of a three stage amplifier is set to an acceptable level. Detailed analysis of transmitting and receiving circuitry is given in Chapter III. 19 III. A. IMPLEMENTED FIBER OPTIC LINK CROSS CONNECTIONS OF THE RS232 The first step in this project was to connect a Hewlett- Packard Series 85 personal computer (HP-85) to a NEC SPINWRITER model 7710 printer (NEC) . Following successful operation the next step was to connect the HP-85 to an AMPEX 210 Video display terminal (AMPEX) , in a null modem config- uration. The functions of the HP-85, NEC, and the AMPEX RS2 32 pins are listed in Tables II, III, and IV, respectively. The reader is referred to section A of Chapter II for formal definitions of these pins. The problem of connecting the DCEs in a null modem configuration proved to be a most formidable one, since manufacturers fail to adhere to any real consis- tencies in their standards of their RS232 pin functions. The cross connections necessary for transmission of the data and for the handshaking between the two DTE's are shown in Figures 3.1 and 3.2. Figure 3.1 shows the minimum connections necessary for proper communication between the HP85 and the NEC. The direction of signal flow and the manufacturers pin titles are also listed in the figure. Figure 3.2 shows the minimum connections of the RS232 required for proper operation between the HP-85 and AMPEX. The pin titles and direction of data flow are also shown. 20 TABLE II HP-85 RS232 PINS PIN FUNCTION 1. EQUIPMENT GROUND 2. TRANSMITTED DATA 3. RECEIVED DATA 4. REQUEST TO SEND (RTS) 5. CLEAR TO SEND (CTS) 6. DATA SET READY (DSR) 7 SIGNAL GROUND 8. RECEIVED LINE SIGNAL DETECTOR 12. SECONDARY. RECEIVED LINE SIGNAL DETECTOR 13. SECONDARY CLEAR TO SEND 14. SECONDARY TRANSMITTED DATA 15. TRANSMITTER SIGNAL ELEMENT TIMING 16. SECONDARY RECEIVER DATA 17. RECEIVER SIGNAL ELEMENT TIMING IS. SECONDARY REQUEST TO SEND 20. DATA TERMINAL READY (DTR) 21. SIGNAL QUALITY DETECTOR 22. RING INDICATOR 23. DATA SIGNAL RATE SELECTOR 24. TRANSMIT SIGNAL ELEMENT TIMING [Ref. 8:p. 47] 21 TABLE III NEC RS232 PINS PIN FUNCTION 1. EQUIPMENT GROUND 2. TRANSMITTED DATA 3. RECEIVED DATA 4. REQUEST TO SEND (RTS) 5. CLEAR TO SEND (CTS) 6. DATA SET READY (DSR) 7. SIGNAL GROUND 8. CARRIER DETECT 19. REVERSE CHANNEL 20. DATA TERMINAL READY (DTR) 23. PAPER OUT / RIBBON END [Ref. 9:p. 22 3-5] TABLE IV AMPEX RS232 PINS PIN FUNCTION 1. EQUIPMENT GROUND" 2 TRANSMITTED DATA 3. RECEIVE DATA 4. REQUEST TO SEND (RTS) 5. CLEAR TO SEND (CTS) 6. DATA SET READY (DSR) 7. SIGNAL GROUND 8. DATA CARRIER DETECT (DCD) 20. DATA TERMINAL READY (DTR) [Ref. . 10:p. 21] 23 PJ ~z. r <r f— <c C£ LD Q CL (/) <t 1— ZD 2 < Q U ui C£" 1— Ld CK i— O OJ • n a . c o •H -P U <D CD [^ OJ c c o u u w 2 /\ A in CO i S V. V LO OJ CO oo r*- CD OJ <r <r LD « Z at: u u u 24 of •H y c o •H P u 0) c c o u X w in CO I s CO (X 25 The second step of this project was to determine which were the data transmission pins and the data reception pins and the pins required for the handshaking. Two pins are readily identifiable. Pin 1 is the chassis ground and pin 7 the signal ground. This is true for both configurations. Considering the connection between the HP-85 and the NEC, pin 3 of the HP-85 is used to transmit the data to the receive pin of the NEC which is also pin 3 . The NEC uses pin 2 to transmit a break signal back- to the HP-85. This signal, of 300 - 700 milliseconds duration, is interpreted by the HP-85 as a priority interrupt [Ref. 9:p. 4-5]. Once this signal is received, the HP-85 ceases transmission of the data. The break signal is transmitted when any of the following conditions occur [Ref. 9:p. 4-6]: 1. 2. 3 paper out buffer overflow ribbon end When the above situations have been rectified, the NEC transmits another signal of the same duration as the break signal and transmission of the data will occur [Ref. 6]. 9: p. 4- Pin 20 is Data Terminal Ready (DTR) line; this is a handshaking line, where a positive voltage indicates that the DTEs are ready to begin transmission [Ref. 6:p. 84]. For the configuration of the HP-85 connected to the AMPEX terminal, pin 3 was determined to be the receive channel of the AMPEX and pin 2 the transmit data from the AMPEX. Pin is the DTR line here also. 26 2 Now that the data lines and handshaking pins have been identified, the next step was to circumvent the handshaking lines. The DTR lines of both configurations are connected to a high voltage and the ground lines are connected to an absolute ground. After doing this we will have two data channels: one transmit and one receive. We now have the desired configuration for transmission on the fiber optic link. B. TRANSMISSION OF THE LIGHT SIGNAL To transmit the signal oh the link the bipolar voltage levels used by the RS232 are converted to TTL levels. On data lines 2 and 3, a positive level voltage (SPACE) a logical zero and a negative voltage level corresponds to (MARK) corresponds to logical one [Ref. 5:p. 14]. The voltage levels used by the HP-85 to indicate a logical "1" and a logical "0" are shown in Figure 3.3. Figure 3*3 shows that the HP-85 interprets voltages between positive 5 volts and positive 15 volts as a logical "0" and the voltages between negative 5 and negative 15 volts as a logical "1". The voltage levels used by the NEC are shown in Figure 3.4. Figure interprets voltages between 3 . 4 shows that the NEC and positive 12 volts as a logical "0" and the voltages between and negative 12 volts as a logical "1". The voltage levels used by the AMPEX could not be referenced. It was assumed that voltages between +5 volts and +15 volts will be interpreted as a SPACE and voltages between -5 volts and -15 volts as a MARK. Since the 27 25 VOLTS PERMISSIBLE OPEN-CIRCUIT VOLTAGE + 15 VOLTS LOGICAL "0" "ON" CONDITION "SPACE"+ 5 VOLTS NOISE MARGIN +3 VOLTS \/\/\/\/\/\/\/\ TRANSITION v y v v v v A A HA A A r i REGION aa/wvw VOLTS - CIRCUIT A8 REFERENCE VOLTAGE -3 VOLTS NOISE MARGIN -5 VOLTS LOGICAL ••V "OFF" CONDITION "MARK'" -15 VOLTS PERMISSIBLE OPEN-CIRCUIT VOLTAGE -25 VOLTS Figure 3 . HP-85 RS232 Voltage Levels 28 [Ref. 8:p. 45] START CODE BITS (CHARACTER BIT K) A /-»-v, STOP 'I +12 V (SPACE) 1 2 3 4 6 'I 1 1 7 P 1 BITS 1 1 OV V (MARK) -12 EARLIEST POINT WHERE NEXT CHARACTER CAN START 110 BAUD. +12 V (SPACE) TWO STOP BITS STOP BIT BITS 4 5 | 6 7 P I EVEN 1 1 1 1 OV V (MARK) 3 START 3 EVEN PARITY IX PARITY -12 EARLIEST POINT WHERE NEXT CHARACTER CAN START 150, 300. 600, ONE STOP Figure 3 . OR 1200 BAUD, BIT NEC RS232 Voltage Levels 29 [Ref. 9:p. 4-1] voltage levels are bipolar they have to be converted to TTL levels required for the fiber optic modules. The device utilized for the conversion is the MC1489, a quad line receiver [Ref . ll:p. 5-120] (Appendix A) . The MC1489 interprets voltages between -3 and -25 volts as a logical "1" and voltages between +3 and +25 volts as a logical "0" [Ref. 5:p. 5-121]. The output voltage range from the MC1489 is 2.5 to 5.0 volts for logical "1" and [Ref. to 0.45 for logical "0" ll:p. 5-121]. The TTL outputs from the MC1489 are supplied to the transmitter circuitry of the fiber optic module. The function of the transmitter circuitry is to modulate the LED of the CAF on or off in accordance with the input signal. The circuitry is shown in Figure 3.5. As Figure 3.5 shows, the TTL input is fed into two exclusive-or gates. On the first gate, U2A, one input is the TTL signal and the other input is always asserted high through a IK ohm pull up resistor. On the second gate, U2B, one input is the TTL input signal and the other input is non-asserted through ground. By having this configuration, Q6 and Q7 are alternately driven on and off. When Q6 is asserted, it allows the LED to transmit a light signal through the fiber. When Q7 is asserted, current is drawn through resistor R15. This design has the advantage that the power supply output remains constant and transient emissions are minimized. Diodes Dl, D2 the bias on the base of Q8 . Diodes, 30 , and D3,are used to set instead of resistors, are a) u a) p -P •H e en c «a u If) •H o u z < < a 31 used so that a constant drive current will be maintained during power fluctuations. C. [Ref. 7:p. 6] RECEPTION OF THE LIGHT SIGNAL The light signal transmitted into the fiber is received by the pin detector in the CAF. The receiver circuitry is shown in Figure 3.6. The light signal received must be significantly amplified before it can be converted into a TTL signal. This is achieved in the receiver by three separate stages: a high gain feedback preamplifier, a low gain differential amplifier and a voltage comparator. [Ref. 7:p. 8] The preamplifier is a three stage transistor amplifier. The transistor array used is CA3127E, a high frequency n-p-n transistor array (Appendix B) . This stage converts the low current levels received by the pin detector into a voltage. The signal out of the preamplifier is applied to a low gain differential amplifier. The purpose of this amplifier is to convert the input to a complementary differential output. The outputs of this stage are applied to a precision voltage comparator, a LT1016. This comparator performs the function of converting the differential analog input to TTL levels [Ref. 7:p. 8]. The TTL levels are then converted to bipolar level by a MC1488, a quad line driver (Appendix C) . The MC1488 is designed to provide a complete interface between the DTEs and the DCEs [Ref. ll:p. 5-118]. The outputs are now suitable for use by the RS232. Once the bipolar levels are achieved, the * 32 •• a) > •H 0) u a) a a) •i-t 33 signals are routed back to the RS232 to complete the trans- mission path. The diagram of the system is shown in Figure 3.7. This figure shows the complete fiber optic link. The actual size of one of these units, including the connection for the RS232 port is D. 6 by 11 inches. RECEIVER MODIFICATIONS As has been seen, the main body of this project has been fiber optic modules. These modules were developed by ADC Fiber Optic Corporation. For our specific application modifications were required to suit our frequency range. The frequency range that the modules were designed for was from 0.4 MHz to 20 MHz for a total bandwidth of 19.6 MHz. Our required bandwidth is only 19.2 KHz, however the frequency range is from d.c. to 20 KHz. This is the bandwidth used by the RS232. It was therefore necessary to reduce the lower end of the frequency response of the modules. Analysis of the transmitter and receiver circuits of the fiber optic modules revealed that in the receiver circuitry, there was a high pass filter between the high feedback pre- amplifier and the low gain differential amplifier. Referring to the receiver circuit schematic (Figure 3.6), capacitor C4 and resistor Rl act as a high pass filter with a cutoff frequency of 1592 Hz. After reviewing the frequencies required for the configurations (HP-85 to NEC, HP-85 to AMPEX) 34 , it was found Ul H > z -i u h- 3 a f^ < a 0. n CD *- d -J • a OjJ »- en cu z • » ij- 5- i a. 00 ** pa i G X -1 1- •H Q e c <u 4J CO >i - w 5 a 5 a _i Q) a & 0* - •H &4 ,/ £ z 1x1 , _i at 3 3: 2 •»* CO GO • • £ u z 35 < a & A • — Ul > u u 1 5 K (U ac that the lowest frequency transmitted would be by the NEC, 1.43 Hz to 3.3 Hz for the break signal. The method to decrease the cutoff frequency was to place another capacitor in parallel with C4. This was determined to be the best solution as the space the circuit board of the modules is limited and the increased capacitance decreased the noise caused from high speed components. The increased capacitance was calculated to be 111.4 microfarads. A 100 microfarad capacitor was placed in parallel with C4 to give a theoretical -cutoff frequency of 1.59 Hz. After this addition was made to the units) , receiver circuit (of both a full duplex bi-directional fiber optic link capable of handling the data flow of RS232 was achieved. Both the connections to the printer and to the terminal performed flawlessly. 36 IV. SYSTEM EVALUATION Evaluation of the transmitted optical power, operating wavelengths, receiver sensitivity, cross talk levels, and lengths of possible links with fibers of different sizes and differing losses are examined in this chapter. In the section dealing with the transmitting optical both units will be examined, however in the other sections only one unit will be discussed as the data compiled for each unit was comparable to the other. A. TRANSMITTED OPTICAL POWER The measurement of the transmitted optical power was done by a Photodyne Model 22XL Optical Multimeter. Each fiber optic module was connected to the optical multimeter via three meters of 62.5/125 micrometer graded index fiber, provided by the manufacturer of the modules. In order to measure the power output a square wave was applied to each of the fiber optic modules* The square wave was generated by a Wavetek signal generator and verified by using an oscilloscope. The signal input frequency range was from 100 Hz to 1 MHz, i.e., the complete operating range of the optical multimeter [Ref. 12]. The unit containing the CAF transmitting at 73 nanometers transmitted a signal at -11.8 dbm (66.1 microwatts), while the CAF transmitting at 865 nanometers transmitted a signal of 37 -12.2 dbm (60.3 microwatts) to give a total power through the fiber, during duplex operation, of -8.98 dbm (126.4 micro- watts) . These measurements were made by connecting the optical multimeter directly to the CAF. The rated power through the fiber, at maximum capacity, is specified to be -10.0 dbm (100 microwatts) [Ref. 13]. It is assumed that the manufacturer rated his product conservatively to be safe. B. OPERATING WAVELENGTHS The system, as has been stated, has two LEDs transmitting at different wavelengths. The wavelength to be received is reflected off the dichroic filter and into the PIN detector, while the transmitted wavelength passes through the filter into the fiber. The operating wavelengths were measured to see if there was a possibility of crosstalk between the two wave- lengths caused by an overlap of wavelengths from the LEDs. The measurement of the wavelengths was accomplished by connecting the CAF to a Photodyne Model 1100XM Fiber Optic Spectral Analyzer and then to the optical multimeter. For the CAF specified to transmit at 73 nanometers, the peak output wavelength was found to be 729 nanometers. The three db points were 717 nanometers and 745.5 nanometers, to give a half power bandwidth of 28 nanometers. The full oper- ating range of this CAF was found to be from 688 nanometers to 771 nanometers, for total bandwidth of 38 83 nanometers. The CAF specified to transmit at 865 nanometers had a peak output wavelength of 862.5 nanometers. The three db points were found to be at 843 nanometers and 874.5 nanometers, to give a half power bandwidth of 31.5 nanometers. The operating range of this CAF was found to be from 821 nanometers to 905 nanometers, for a bandwidth of 84 nanometers. Thus, there is a 50 nanometers separation between the two wavelengths. C. RECEIVER SENSITIVITY LEVELS The receiver sensitivity level of the PIN detector was specified, in the worst case, as -24.5 dbm. However it was observed that the detector was able to receive a signal at a level of -44.0 dbm and the receiver circuitry was able to convert it the original TTL signal. This represents an increase of 79.5% in the sensitivity level of the detector. It was also observed that, although a signal below -44.0 dbm could be received by the PIN detector, it would not have sufficient power to trigger a response from the first stage amplifier of the receiver circuitry. D. CROSSTALK Four crosstalk measurements were made on the fiber optic modules. These measurements were made with different com- ponents on and off the modules to see their effect on crosstalk. A 1 MHz square wave was applied to the fiber optic modules. The 1 MHz frequency was chosen so that the effect of 39 a high frequency on the unshielded receiver circuitry could be observed. A square waveform was chosen so that a spectral analysis could be accomplished and the resulting sine pulse efficiently analyzed for center frequencies and power levels. A spectral analysis of the applied wave is shown in Figure 4.1. Figure 4.1 shows the spectrum of a sine pulse with a power level of -18.80 dbm at a center frequency of 1 MHz (as indicated by the annotation to the left of the spectral peak) Figure 4.2 shows the measured spectrum of the sine pulse at a center frequency of 1 MHz with a power level of -79.10 dbm on the other receiver. This power represents the crosstalk due to the circuitry of the transmitter. In this observation the receiver circuitry was unshielded from the transmitter. Figure 4.3 shows a sine pulse spectrum at a center frequency of 1.0 MHz at a level of -81.30 dbm. This represents the amount of crosstalk that results with the receiver circuitry shielded from the transmitter. Thus the shielding provided an additional isolation of 2.2 db. Figure 4.4 shows a sine pulse at a center frequency of 1.00 MHZ at a level of -77.30 dbm. This is the crosstalk due to both the transmitting circuitry and CAF, mounted on the fiber optic module. In this case the receiver circuitry was left unshielded. Figure 4.5 shows a sine pulse at a center frequency of 1.00 MHz at a level of -78.50 dbm. This the crosstalk level due to both the transmitter and the CAF, but this time the 40 1 N CO u w w ^ • • K s _i H Z < cu w - Cm s w J- c •H N N ... - - - . .- -- T3 O . en a) •H rH a / — .=_ CO > --- - ... - G G n r i i .. • . _. N . N E n I A ^ O O H m -TJ & & GO V ©-. en Q CO < s (Y. UJ . t-< u. UJ a: CX* W Eh Z w u r-f I 1 L \ m D 41 o H Sh en •H (0 tf Em N 1 la E 2 00 "0 S S Q S -" N «. 2 • t u w w K s oo cc i - 2 H 2 < & T ID (h » W CO (0 -p cn o u u "> J & I •H f P N •H o _. ' 3: O «; r> 5 ID "U CD > Q a) •H W c I D k - — - N I o o r E n c* m . i IN '__ f . 2. E SJ m D s W s v 1 «-< rH J Eh rH fM rH ^ 5 CQ CO w S S) 0) r 1 1 u. UJ 2 o o o • -®— < 2 1 . a: m I a) T3 rH .c Z W H h < n T3 (n) 42 2 W U •H . .... r MHz dBm 30 S tSJ 3 ffi S CO H • CO ^r • (D or u w w H Z < Cm W i • rr in CU 5 w -- p en w o u - i >i u 3 N O ffl CD > T) P •H U u u Q) T3 S ^ .c w Z LU H H N 5i f. < o o N E N in E a: 00 "0 uj Q Q < 2 ^ . ii UJ a: 5 6 n CD o o H « Q CO w *-• Eh Z w u a) i i . . \ m 43 3: CQ W W a a) 3 •H fa _. 7 r X E s m u S S S 0) N V U W W 1 00 • • H 2 < d, w 04 rH (0 a a u a s CQ 1 < U P •H N >1 H •H O 3 r> - 2 CQ > m •H u T3 a> T3 rH Q % (U •H Z N Li J D \- 2 \- < Q O N E M s CD Q o o H -©--.- « w IS Hi 1 O s CQ • E CD "0 U.I V s < A •H 2 H U 1 1 i li UJ or m r • r a c C3 44 W H s * • ^* M 3 HCP • N X 2 T r E CD N 63 }- 63 ID «-• X z K 2 co t-H CO u w CO ^ H 1 f •t— <n -M to to u P* s CO co u 1 En < 1 .fl -P 1 •H N >i u •H '" £ CQ > * CD D - —- • w ri r> *- - • u H O 63 • LU fr- 1- • < 2 1 E o (" n m 1 CD V UJ q in V -®— S CD < 2 m 63 .'_ CO 5 in LU m D 63 45 CQ f CO 35: K w .. w -5 Eh 25 J? o 1 & N N O O • a: •H - I IN -x-tj E rH 1 Z W Q) U 3 & receiver was shielded. The shielding gave an additional isolation of 1.2 db. The object of these measurements was to observe the crosstalk due to the electronic emissions of the transmitter and the optical crosstalk of the CAF. Overall the CAF was observed to increase the crosstalk levels 1.2 to 2.8 db. This crosstalk is possibly due to internal reflections of light within the CAF being received by the PIN detector. Although crosstalk is present in the system the levels present at would not be sufficient to cause an erroneous response from the receiver. E. TRANSMITTED AND RECEIVED SIGNALS The transmitted and received signals of the HP85 NEC con- figuration are shown in Figure 4.6. This diagram was obtained was obtained by using the Hewlett-Packard 1615A Logic Analyzer. Channel shows the transmitted break signal from the NEC (refer to section A of chapter 3) , while channel 1 shows the received break signal on the fiber optic module, channel 6 shows the transmitted data from the HP85 while channel 7 shows the data received at the end of the fiber. The distance of transmission was 1.27 kilometers on 50/125 micrometer fiber. It is noted that the HP85 is triggered on the trailing edge of the break signal. In Figure 4.7 we see the data transmission of the HP85- AMPEX configuration. Channel 6 shows the transmitted data from 46 > n to Q o X N. X cnwo 3 3T O «H O O <Q X. -J *- Ill hLU -J Q3E rH (0 c •H W a w z in O U L_J i UJ (J in 00 < cc 1 k- s LL O O XT >- < or a < •-• *-* <o H <~ a a x az H CD -J CL co l-« 0) u 1-1 >-* >-1 Q CD O 2 *: 3T _J < »-• VO z- •H •-• O ;rf h w m en 47 (O ^> a en s v s en en 3 s O O (J UJ 1LU CD. • en »-i c i_i •H »-* -J Q. s: in a u W X i LU w U (X m CO l O O X_ er >- ^ a < •—a~~ s < i< _j Q. hor en <— u I— a o — < a a — >- 2 u_ a _i »- X 2 2 o a a <J h- ej 2 2 •- <~ *— < _J z s: _j Q_ U •— < X _ i- h•—4 1 a) i i— • Cn •H fa is: LU o ^ CM (T) in 48 HP85 and channel 7 shows the received signal after the 1.27 kilometers link. Signals of various frequencies were applied to the fiber optic modules to obtain the frequency range of the modules. The input frequencies ranged from 1 Hz to 5 MHz. Again the waveforms were chosen to be square waves so that a spectral analysis would be easy accomplished. Two different fibers were used to determine the losses due to the connectors and to observe the minimum sensitivity level of the detector. The frequencies and amplitudes observed are listed in Table V. Measurements were made of the amplitudes of the signal at the input to the fiber optic modules and after transmission on meters of 50/125 micrometer 3 graded index fiber to calculate the connector losses. On the average, depending on the orien- tation of the fiber, a connector loss of 1.25 dbm was . observed. Transmission on the 1511 meters length of 100/140 micrometer fiber was performed as the author believes that this would be a realistic distance necessary for a high speed data link. From Table V it is seen that at 5 MHz the maximum sensitivity of the PIN detector is reached (-44.0 dbm). A spectral analysis of the signals listed in Table V are shown in Figures 4.8 to 4.25. Explanation of these figures follows. Figure 4.8 shows the spectral analysis and power level of a 1 Hz square wave that was applied to the input of the fiber optic modules. As seen in Figure 4.8 the spectral analysis the waveform is a sine shape at a center frequency of 49 1 Hz with a TABLE V APPLIED AND RECEIVED SIGNALS FREQUENCY REC. SIGNAL 3M F.O CABLE (50/125 urn) INPUT SIGNAL (dbm) (dbm) REC. SIGNAL 1511M CABLE (100/140 urn) (dbm) -6.90 -9.60 -10.30 -17.80 -20.60 -36.70 -18.50 -20.50 -35.90 10 KHZ -17.80 -20.50 -35.60 1 MHZ -18.40 -21.00 -37.60 5 MHZ -19.80 -21.80 -44.00 1 HZ 100 HZ 1 KHZ 50 N £ o o • r> § Q* W O o o H • SB w (T3 c en •H W TJ Q) •H N S o o H r-i a N 3S > CO N B o N s o o H • tt w 2 W Eh r 51 i r» 5 CQ W W « • *tf a) M 3 D> •H fa power level of -6.90 dbm. A 1 Hz signal was applied to ensure that the modules would be able to respond to the lowest freq- uency seen experimentally for two DTEs, without experiencing significant delay or distortion on a long distance link. Figure 4.9 shows the same sine spectrum after 3 meters of fiber. The level of power is observed to -9.60 dbm. Since 3 meters of fiber has a negligible amount of attenuation at 7 db/km the losses seen here are attributed to connectors. Here a total connector loss of 2. 1 db is seen. Figure 4 . 10 shows the 1 Hz sine spectrum after trans- versing the 1511 meter fiber. A signal with a center frequency of 1 Hz is observed at a level of -10.30 dbm. This power level is more than sufficient to trigger a response from the receiver circuitry. Thus the link would be able to handle the lowest frequency transmitted by the DTEs. Frequencies of 100 Hz, lKHz, and 10 KHz were applied to the modules as these would be typical of the frequencies seen by the RS232. Figure 4.11 shows the spectral analysis of 100 Hz square wave applied input signal. The sine spectrum shown in Figure 4.11 has a center frequency of 100 Hz at a level of -17.80 dbm. Figure 4.12 has the same sine spectrum after the fiber. This also has a center frequency of 100 Hz at 3 meter a level of -20.60 dbm. This implies a total connector loss of 2.8 db. 52 E * DO ~0 N u £ QT * Z (S3 O O (0 . • CD r> I | Oi w o o H • 04 w u U) -p a) g a) N < s O c o H •H0^ 5 W CQ > N .-I fl DO D S N Z H h < s o UJ a o -N E a: LU DO "D N —m 2c E n 0) o o v & w S E-i < Z w u CD . Ll OJ a\ CO _L I \ DO '0 53 W W a •H r hi (I) n , H IV it CO *.£' > 1 N u w O O H o • • o en § CM W cu » w tt Q) P X H 0) ID H u P N < o n 5 CQ > iH s z (0 C •H W N N III X o G N N X o O E m n s w a ui w < 6J CQ 2 W O ti Ul or in o r 54 a) 9 CP •H N I N E K o o H m Tl . & S .-. G) (JD . o w co o o m • 55 r. < ft CO ft S CO (0 c •H CO TJ a) •H .H N s O CU < N r> CO > o o rH •o H z in ih- N S < a) 3 N C7> •H E ,m O O "0 CO CO w ft CD ft w Eh Z w o IL 111 ft \ m n ft 55 ft N s o O H z < w u w w o o n & 3 w • U) M <D 4-> <n 0) < N s o m 3 03 > N N X o o H « w H Z w u 56 <0 c 0* •H w N X o o X o H fM iH 5 u 3 CQ W w s <r 0* •H h Figure 4.13 displays the 100 Hz spectrum after the 1511 meter fiber at a center frequency of 100 Hz and a power level of -36.70 dbm, well within the receiver sensitivity limit of -44.0 dbm. In Figure 4.14 a spectral analysis of an applied 1 KHz square wave is shown. The resulting spectrum pulse has a frequency of 1 KHz at a power level of -18.50 dbm. This same signal is observed in Figure 4.15 after the 3 meter fiber, a power level of -20.50 dbm, to give a total connector loss of 2.0 db. This improved connector loss may have been the result of an improved orientation of the fiber to the connectors of the fiber optic modules. Figure 4.16 displays the spectrum of the signal after the 1511 meters of fiber. A center frequency of 1.0007. KHz at a power level of -35.90 dbm, still within the limits of the receiver. Figure 4.17 shows a spectral analysis of an applied square wave at 10 KHz. The figure shows a center frequency of 10 KHz at a power level of -17.80 dbm. Figure 4.18 has the spectrum after the 3 meter fiber to give a total connector loss of 2.7 db. Signals of frequencies 1 MHz and 5 MHz were also applied to the fiber optic modules. These high frequencies were chosen as they would reflect a data flow that would be seen on a local area network. 57 N I E m "a s . s s s N s o o H z r\ . en x 2 i «< cu 03 u w w o o • en r> M 04 P CO s a) S <u H H in H a) N K o < (0 C CO 2 •H W ffl CD "0 > N EC S o o H z lil N < Q O E N < CD N •N E X U y "0 a s < O O S (Z H S at w H z w u (D u. LU m £ 58 s o H 5 r> H T • CQ 0) cn ^ 9 w a D> •H Cn N K 2 o o H • u w CO o • o n 2S < & 3 CO CO a. c tP •H CO T3 0) N s o o n N > N N O O K o H CQ CO W w u 59 <D U 3 CP •H . __ ... """" ... N r z e m T) & .. K) S) (3 ID • * .-. (V) . _ . N — B o o H • (M X * 1 2" S & co u w CO o o • cu IS CO 0) U 0) 4J CU s r> M 0) 4J <W N X o o - < r-\ ITS C tP •H UJ TI 5 CQ > CO N HI N & «-i •^ HI - - 1 ^ 1 <| ___ E — O o N m oc XI Ul N O o H « v eg W PC • ,. < X u E-» 2 m u ii Ul m "0 Ll Cr cj 60 H O H IS CQ CO W S t4 •H t X r E X. CD '0 N (S3 Q Q 0) • <-• if) • • m q: u w w o o M 2 o o rs iH i s < cu w CO W M 0« 4J (1) 5 w <D X If) 0) N s o o <n 5 cu > m v s z H < .H (d c 0^ •H w N Li N H < o o N E N CD se 2 -N E W -^ Q S lL UJ a: & CC m "0 < o o H « w Z w u •S— . o H S pa • IN CD S s ID CO E-t \ m. "0 61 w w S VO H • ^r d) u P CP •H &-. N Bfl 5 o o • in u w w o o • 55 < PU w 04 IS en rH c •H 03 0) •H rH N X o o n £ CQ > A < N s o H r* H N N s o o o H « W t E-« 55 W u 62 X o o H 5 CQ w tf • ** 0) 0> •H (X4 - " T i kHz dBm N 90 K Em 9 0( 5( o o 10. • -20. If) s < Cu w u w w o o • r> rn Li tu 5 w <1) +J 0) s - -P <4— N — — m D S X o o o S 03 > -, rH <0 c rp •H w N B o iH «-4 n z N UJ N h < O N E o iV m IN _E s o o o H « w Eh 2 w o "PI U • E CD "0 UJ _1_ S S ID . (3 ©•- < <S i ii .!_. __ III \ CD -5- S 63 X O o H s CO H • (1) Ll 03 3 W W •H 5 Cn &H Figure 4 . 19 shows the same 10 KHz sine spectrum after the 1511 meter fiber at an amplitude of -35.60 dbm, a level that would still trigger a response from the receiver circuitry. Figure 4.20 shows a spectral analysis of an applied 1 MHz square wave with power level of -18.40 dbm. Figure 4.21 shows the signal after the 3 meter fiber at a level of -21.0 dbm, giving a total connector loss of 2.6 db. Figure 4.22 displays the received sine pulse after the 1511 meter fiber at a center frequency of level of -37.60 dbm. 1 MHz and a power This signal is 6.4 dbm above the threshold of the receiver circuitry. Figure 4.23 shows the spectral analysis of the highest frequency that the fiber optic modules were able to discern, 5 MHz. This sine pulse has an input amplitude of -19.80 dbm. Figure 4.24 has the same signal after the 3 meter fiber at a level of -21.80 dbm to give a total connector loss of 2.0 db. Figure 4.25 shows the received sine pulse after 1511 meters of fiber. The center frequency is still at 5 MHz, however, the power level of the signal is seen to be at the maximum sensitivity level of the receiver, -44.0 dbm. The fiber optic modules frequency range is effectively from d.c. to 5 MHz, an increase of 250 times that of the bandwidth of the RS232. The capability of the modules to handle 1 to 5 MHz signals opens the system up to the possibility of being utilized on a local area network. 64 N X 1 1 E JT CD XI N hrt S Q Q S (0 s in ,-. 2 O O in (T) U w co o o • CO r> u § cu +J &. 03 CO I or s a) £ H H LO H N < s rH o <0 o C m •H S CO CQ > N . m u s z H I< N 111 N o N o I C C E O CD O o H « h "vj 1 1 E 'a CD "0 LU S) (D -© r V s s W Eh . IT) < S 01 2 W a - •H 1 1 Ll. UJ or en \ m "0 65 Vi •H En N 1 2 E CD H s s s N cj CO O O GO • e • «H a: z < cu w 2: Cm 5 w rH (0 C ^ CT •H W $. a> •H rH N a 5 < O N r> S 5 03 > CD D H O Z H < • Lll CO N CD IN _t u N 1 E a: UJ (S3 . 5: Cn CQ s ^ H « w CO H 5 Eh 2 W U •-« «-• 1 _l IL LU J-i •H ¥ ®— a Q CO < S S s 3 X CD a N E T I \ m "0 4^ a 66 * 7V~ N 1 I E Z CD "0 S S S S <S N g O O H z S3 & w • or i u w c/3 o o • r> A 5 03 3 W ^ 0) 4-> 0) s M a) 5 N c O r> •H W N > u & z w < o o E n m -N -ie-^ N E m "0 UJ < a: r & f\J .J II u. W "* s s -© s N ^ % h\- \ m u 67 s § o o H « w Eh 2 W u o H s 03 • Is CN Q) CP •H fa W S N W § o o y t T) N \) S s (0 o w w 6 o • • rH o . r> r- § & w & S w a) p a> s in N O (0 c •H W > N in N z N ui O O O CQ CO w w 111 n 2 W u ft u. in in n LI 68 CM CS a) CP •H N i i I E S CD "0 S s s S CO N S O o H • • • ID U) «- q: u w CO O o • i § eu w cu » CO ca 5 c •H CO 0) •H N rH Q* £ o N a < S . CQ in N Tf § o u 3 > CO TJ s »-< z h- H < . 2 O O h N E n s o p m i IN E B in CO « a: IS 0) 2 W U (Z CO -o S V LU . a s w Eh < z . ID «-" 1 f> i ii .i . 111 or \ m "0 J** s 69 a) tP •H 12 CO CO w a Cn N I i I I E in Tl N S O O H If) (M • If J o w to o o n • in § 04 CO cu 5 to u 0) -p d) S- 0) 4J N < •3 o n c C7> •H CO 5 (S III N > n m N O n N E E n N m S o o s ui S) 00 ^ ®-r in Tl in rr < (S) «H . l\l If) « w B 2 « u I L I. ti iii if \ in n 70 • iH s 0) V4 03 D CO CP •H • - GJ g o w K Uh N 1: :r f m N i) g o o H • !/) vf I il' § I 04 5" w u w g o o w r> ^1 • 04 5 w <u IS If) ^ 0) .p <H N < s rH O r> rtJ C 0^ •H S W CD > N (1) "0 If) K>. . -• Z N III N 2. o I 2 O O "J N « o s CQ • If) m (Y Tl UI W « -W 01 w lO (N • <D U P D> •H Pm E-t 2 W u iy IS) U. Ill (T ui TJ 71 • This set of data also showed that on the average, depen- ding on the orientation of the fiber, a connector loss of 1.25 db could be anticipated for a professionally manufactured cable. This figure will be used in the calculation of ideal link distances. F. LINK DISTANCES One of the limiting features in using the RS232 link is that it is limited to a maximum length of 50 feet for baud rates in excess of 300 baud [Ref. 8:p. 169]. With the utili- zation of a fiber optic network lengths could be increased to nearly 100 times that, for any baud rate that the DTEs are capable of transmitting and receiving. A link distance was calculated for 50/125 micrometer graded index fiber with a loss of 7 db/km. Using the man- ufacturer's specification the optical power coupled into the fiber would be -20.0 dbm. The maximum rated sensitivity for the detector, -25 dbm as specified by the manufacturer [Ref. 7: p. 13]. An average connector loss of 1.25 db per connector was measured and was used in the calculations. An optical budget of 7.0 db was obtained through these calculations, (transmitted power - (connector loss + receiver sehsitivity) ) This would provide a link distance of 1.00 kilometer. Experimentally, using 200 meters of 50/125 micrometer graded index fiber, at 7db/km loss, and an attenuator (since greater lengths of 50/125 micrometer fiber were not available) 72 a link distance of 1.27 kilometers was obtained, . an increase * of 27.0% over design specifications. For a 100/140 micrometer graded index fiber, at 7 db/km loss, the manufacturer's maximum designed optical transmitted power coupled into the fiber is -11.2 dbm. Using the specifications above, a calculated link of distance of 2.34 kilometers is possible. Experimentally a link of distance 1.511 kilometers was achieved. A greater distance may have been achieved but the laboratory attenuator available was not suitable for use on the 100/140 micrometer fiber. G. PRODUCT COMPARISON A comparison of the costs and other major characteristics of this unit and other equivalent units is shown in Table VI. From analysis of Table VI it can be seen that the fiber optic unit described in this project is comparable to commercial units on the market in both price and in performance. 73 TABLE VI PRODUCT COMPARISON UNIT MAX. FREQ. FOM HPIB 5MHZ 4.8MHz TOTAL PRICE MANNER OF OPERATION BI-DIRECTIONAL FULL DUPLEX HALF DUPLEX 593.00 2770.00 EXPANDABILITY LINK DIST. 1.27 K YES (AT A COST OF 300.00 PER STATION 1.25 KM ) YES (AT A COST OF 860.00 PER STATION ATT LIT. 19.2 KHz BI-DIRECTIONAL FULL DUPLEX 520.00 1 KM MHz BI-DIRECTIONAL FULL DUPLEX 1998.00 8 KM 2 NO UNKNOWN LEGEND: FOM - FIBER OPTIC MODULES HPIB - HEWLETT-PACKARD INTERFACE BUS EXTENDER [Ref. 14] ATT - ATT ODL RS232-2 FIBER OPTIC MODEM [Ref. LIT. - 15] LITTON INDUSTRY E03 671 [Ref. 16] 74 ) V. CONCLUSIONS As can be seen from Table VI the link designed here would have capability of expanding because of the great bandwidth offered by the use of fibers. The link presented in this thesis is a point to point link, but the same principles would apply to higher order networks. Stations could be added on this link, but it would be at a minimum cost of three" hundred dollars per station. Another limitation of expanding onto a higher level network would be the optical power. The optical budget of each station would have to be observed to ensure that one station did not drain the optical bus of such a large amount of power to render the other taps useless. Some possible solutions to this problem could be to inter- change the LEDs in the CAFs with laser sources or to use more sensitive detectors. A different approach would to have each station at a differing wavelength within the CAF. The only problem with scheme would be that it would not be interactive. In essence, this thesis is the beginning point of a possible inexpensive fiber optic local area network. 75 APPENDIX A MOTOROLA MC1489 QUAD LINE RECEIVER DATA SHEETS MC1489 MC1489A &30TGFS&L.A QUAD QUAD MDTL LINE RECEIVERS LINE RECEIVERS RS-232C SILICON MONOLITHIC INTEGRATED CIRCUIT The MCI 489 monolithic quad line receivers are designed to interequipment with data communications equipment conformance with the specifications of EIA Standard No. RS-232C. face data terminal in • Input Resistance - 3.0 k • Input Signal Range • Input Threshold Hysteresis • kilohms to 7 - ± 30 Volts Built In Response Control a) Logic Threshold Shifting b) Input Noise Filtering L SUFFIX p SUFFIX PLASTIC PACKAGE CERAMIC PACKAGE CASE 632-02 MO-O01AA Input TYPICAL APPLICATION n> A LI Wotoonw r— Control A Li. UM «t Clrvl KIWI iMMCOWCTiiiG CASK Ourovf A rr i Input S (T Cmntrol 9 I— Ouioot 6 (V KTincoaarcriM; on mciowt - | caiu I mm loccnuinn EQUIVALENT CIRCUIT SCHEMATIC •tisroiist control : (1/4 CASE iZNcc ^& ^t5 i5] —'Control O nJOulpul O IQJ 5-120 76 Inoul C S"»*pon«« Con.ro, C 8| Output C o o Input siRiniaiin Of CIRCUIT SHOWNI MOTOROLA LINEAR/INTERFACE DEVICES 646-05 tcnouKO MC1489, MC1489A MAXIMUM RATINGS »25°C (T A • unless otherw.se notedl Symbol Ratine, Value Unit Power Supply Voltage vC c 10 Vdc Input Voitaoe Range V|R 130 Vdc 'L 20 mA Ouipul Load Current Power Dissipation (Package Limitation, Ceramic and Dual Plastic In Line Package! Derate above T A • »25°C Operating Ambient Temperature Rang* '0 1000 mW 1'ftJA 6.7 mW/°C TA Oto <75 T stg Storage Temperature Range ELECTRICAL CHARACTERISTICS (Response control pin is -65 to °C U M 75 open.) (V<;c - +5.0 Vdc 2 10%. T A = C to + 75'C unless otherwise noted) Characteristics Symbol Min Typ Max Unit l|H 3.6 — 8.3 mA — -8.3 mA + 25 Vdcl (Vih = +3.0 Vdcl Positive Input Current (V|h Negative Input Current (V|i_ — -25,Vdc) (V| L = -3.0 Vdcl 0.43 Input Turn-On Threshold Voltage (TA - + 25'C. Vql * °- 45 v A - + 25'C. Voh » 2-5 V. Output Voltage High Ii_ 1.0 (V|h Low 1.75 (Vil (All « 0.75 » -0.5 mA) Open Circuit. I(_ « -0.5 mA| V H » 10 mA) vol 0.75 V, L l - 3.0 V, li_ Gates "on." ou t » mA, V|y l (V C C ' 5.0 Propagation Delay Time 0.8 2.5 4.0 5.0 2.5 4.0 5.0 (RL » 3.9 (Rl - 390 Propagation Oelay Time Time ice PC 3.9 kill (Rt - 390 — — — — 'TLH kill. •PHL kill tTHL 1.25 Vdc 0.2 0.45 Vdc -3.0 -4.0 16 26 mA mA 80 130 mW ns 1.) <PLH kill 1.25 — — — — Vdc -1%, T A - +25X. See Figure (Hl Time +5.0 Vdc) +5.0 Vdc) (V|h SWITCHING CHARACTERISTICS Fall 2.25 0.75 ios Power Consumption Rise 1.95 Vdc MC1489 MC1489A Output Short-Circuit Current Power Supply Current 1.5 VlL - -0.5 mA) (Input Output Voltage Vdc VlH MC1489 MC1489A » Input Turn-Off Threshold Voltage |T -3.6 -0.43 hL 25 85 120 175 ns 25 50 ns 10 20 ns TEST CIRCUITS FIGURE 1 — SWITCHING RESPONSE FIGURE 2 — RESPONSE CONTROL NODE Vft «E<i ± ESP0NSE N00E 1/4 UCI489A tUmrdtTHl V,„ c> «- measured Iff-. - C. caoacitor R. resistor C(_ - 15 of = total parasilic capacitance, -e>Vrj 90". 11 if which includes probe and wiring capacitances MOTOROLA LINEAR/INTERFACE OEVICES 5-121 77 lor none liliennq lor thfesriold shilling MC1489, MC1489A TYPICAL CHARACTERISTICS tv CC " 5.0 Vdc. FIGURE 3 TA • *2S C unlsss otherwise nof«dl — INPUT CURRENT — MC1489 INPUT THRESHOLD VOLTAGE ADJUSTMENT FIGURE 4 10 ^r^ 6 •>o SO •CO V| •40 i 2.0 5 <° -5=-T~Vj^ -40 - _ 3 20 2 io 1 «T 13k II k _V,h Vth V.h •SV •SV — — > 1 " • _J -20 -IS SO -10 V,„.IKPUT •iO -10 >n 'It «IS 20 30 FIGURE 6 — INPUT THRESHOLD VOLTAGE •trjus - " \ -"rl -«T- -5 II _«s 10 — E 11 »— '« S 1 k. Vih 5 V -= °~ r«T- -V| TEMPERATURE MCI«9AV| H 2 20 -Hi 10 24 sn «o >20 Vv INPUT VOLTAGE (VOLTS) — MC14WA INPUT THRESHOLD VOLTAGE ADJUSTMENT —>r (0 —»> r -10 10 VOLTAGE (VOlTSI FIGURE 5 30 4. VllH V|Hl -10 -10 V «. »« MC14M V| H " —J— i I 01 — - - - — -2 -1 (I • V). INI 1 ot '- 04 ~,l HCH y<a«9A vn S >-02 u 1 -] — ... VllH "V|H(. "J '2 •! 1 _L o *4 -c 1 r. — INPUT THRESHOLD versus POWER-SUPPLY VOLTAGE FIGURE 7 20 VIH* "3 Ml < 1 Ml 1 ( 1JTVOI T*GEI\ rOLTSI > 3 o 1 — -SV \ -SO E0 — «T _5k > •JO _"T _«T. J0 |——>. M i— VW - V^M. C14J9A C14JS — " »— 2 X 40 10 V(X POWER SUPPLY VOLTAGE (VOLTS) MOTOROLA LINEAR/INTERFACE DEVICES 5-122 78 te« if (RAT U«El°C 1 1 •170 MC1489, MC1489A APPLICATIONS INFORMATION The MC1489 input has and turn-off of 1.0 volt for a typical hysteresis of 250 mV. The MC1489A has typical turn-on of 1.95 volts and turn-off of 0.8 volt hysteresis for noise rejection. General Information typical turn-on voltage of 1.25 volts The Electronic Industries Association (EIA) has released the RS-232C specification detailing the requirements for the interface between data processing equipment and data communications equipment. This standard specifies not only the number and type of interface leads, but also the voltage levels to be used. The MCI 488 quad driver and its companion circuit, the MC1489 quad receiver, provide a complete interface system between DTL or TTL logic levels and the RS-232C defined levels. The RS-232C requirements as applied to receivers are for typically 1.15 volts of hysteresis. Each receiver section has an external response connode in addition to the input and output pins, trol thereby allowing the designer to vary the input threshold voltage levels. A resistor can be connected between this node and an external power-supply. Figures 2, 4 and 5 illustrate the input threshold voltage shift possible through this technique. This response node can also be used for the filtering of high-frequency, high-energy noise pulses. Figures 8 and 9 show typical noise-pulse rejection for external capacitors of various sizes. These two operations on the response node can be discussed herein. The required input impedance is defined as between 3000 ohms and 7000 ohms for input voltages between 3.0 and 25 volts in magnitude; and any voltage on the receiver input in an open circuit condition must be less_ than 2.0 volts in magnitude. The MC1489 circuits meet" these requirements with a maximum open circuit voltage of one Vgg. The receiver shall detect a voltage between -3.0 and -25 volts as a Logic "1" and inputs between +3.0 and + 25 volts as a Logic "0." On some interchange leads, an open circuit of power "OFF" condition (300 ohms or more to ground) shall be decoded as an "OFF" condition combined or used will many combinations The MC1489 circuits are particularly useful for interfacing between MOS circuits and MDTL/MTTL logic systems. In this application, the input threshold voltages are adjusted (with the appropriate supply and resistor values) to fall in the center of the MOS voltage logic levels. (See Figure 10) The response node may also be used as the receiver input as long as the designer realizes that he may not drive this node with a low impedance source to a voltage greater than one diode above ground or less than one diode below ground. This feature is demonstrated in Figure 1 1 where two receivers are slaved to the same or Logic "1." For this reason, the input hysteresis thresholds of the MC1489 circuits are all above ground. Thus an open or grounded input individually for of interfacing applications. cause the same output as a negative or Logic "1" input. Device Characteristics The MC1489 interface receivers have internal feedback from the second stage to the input stage providing input line that must meet the RS-232C impedance still requirement. FIGURE 9 — TYPICAL TURN-ON THRESHOLD versus CAPACITANCE FROM RESPONSE CONTROL PIN TO GNO FIGURE 8 —TYPICAL TURN-ON THRESHOLD versus CAPACITANCE FROM RESPONSE CONTROL PIN TO GNO MC1489A l?pF \ 100 pA SOOpA 300 pf \ V >00 1000 PW INPUT PULSE WI0IM 10 000 1000 100 PW INPUT PULSE lot) \ MOTOROLA LINEAR/INTERFACE DEVICES 5-123 79 MOTH Inil ioooo MC1489, MC1489A APPLICATIONS INFORMATION Icom.nuedl FIGURE 10 — TYPICAL TRANSLATOR APPLICATION — MOS TO DTL OR TTL • 'i Vdt r MCM89 MOS FIGURE 11 1 L ^ i«00 •4Ydc i i « TTl rl.-J -, OTl 10GIC *-"GG ' ( |" ~. — TYPICAL PARALLELING OF TWO MC14«9A RECEIVERS TO MEET RS-232C RESPONSE CONTROL PIN INPUT INPUT RESPONSE CONTROL PIN - o- MOTOROLA LINEAR/INTERFACE DEVICES 5-124 80 APPENDIX B RCA LINEAR INTEGRATED CIRCUIT CA3127E HIGH FREQUENCY N-P-N TRANSISTOR ARRAY DATA SHEETS CA3127E Features: High-Frequency N-P-N Transistor Array Gain-Bandwidth Product Power Gain - 30 dB Noise Figure » 3.5 Low-Power Applications at Frequencies up to For 500 RCACA3127E* of consists purpose silicon n-p-n transistors general- five on a common © © © © © 3 <2 transistors fj in excess of »alue of CA3I27E VHF dc provided to each of the terminals lor the individual transistors and a separate substrate connection has been provided for minimum application flexibility The monolithic construction of the CA3I27E provides dose electrical and thermal matching of the Access 1 GHz "VHF amplifiers is O©©.0©©0© mixers IF Converter RF/mixer /oscillator IF amplifiers Sense amplifiers Synthesizers Synchronous detectors Cascade amplifiers 3JCS-ZZZI* Fig. t - Se/itmttic diagrtm of CA3I27S. transistors. live CA3127E The is supplied in a 16 lead dual-inpackage and operates over the full temperature range of -55 to + 1 25°C. line plastic military ' (typ.) Multifunction combinations— GHz, making the to 500 MHz. 1 from useful > 100 MHz at 100 MHz on a common substrate Applications: Each of the completely exhibits low 1/f noise and monolithic substrate. i dB Five independent transistors MHz isolated (f-p) Ityp.) at Formerly RCA STATIC ELECTRICAL CHARACTERISTICS CHARACTERISTICS TA 25°C LIMITS TEST CONDITIONS TA6206. Oev. No. at Min. MAXIMUM RATINGS, UNITS Typ. Max. For Each Transistor: Absolute-Maximum Values: Collector-to-Base •0//ER DISSIPATION. P 8B mW Any one transistor Total For TA 425 up io ?S°C > 75°C mW 6.67 mW/°C -55 to H 25 C -65 tot 25 C . Storeqt I LEAO TEMPERATURE I0URING SOLDERING): At distance t / 1 6 1 1 132 inch 11.59 for ± 0.79 mml 10 seconds 32 - V mA, 15 24 - V 20 60 - V 4 5.7 - V - 0.5 uA - 40 nA Ir; Breakdown Voltage Collector-to-Substrate I Breakdown Voltage TEMPERATURE RANGE: 0r»renng 20 1 Ig » Derate Linearly at AMBIENT Breakdown Voltage Collector-to-Emitter Package: For T A IC" 10 uA, E »0 l : C1 - 10uA, lg>0, Emitter-to Base It: Breakdown Voltage* »10uA, lc«0 Collector-Cutoff-Current V CE -10V, Collector-Cutoff-Current VcB= lg = mas I t-265 C apply tor each transistor in DC mA mA IC*0.1 mA IC * 5 mA Forward-Current V CE Transfer Ratio - 6 V me device: Collector-to-Emitter Voltage. Coiiectorto-8ase Voltage. Collector. to-Substrat* Current. i 1SV V V V(-£q Vqqq 20 20 . Voltage. Vj-jq* 20 r 'The collector of each transistor of the >s isolated mA Base-to-Emitter Voltage Vce - 6 V must be connected to 5 35 88 IC 1 40 90 - 35 85 - 0.71 0.81 1 rnA IC"0.1 Colledtor-to-Emitter IC Saturation Voltage 10 mA, lg * - IC IC " CA3127E from the substrate by an integral diode. The substrate Iterminal 51 the - 10 V. E = Irons case Th* following ratings Collector lg*0 1 rnA mA 0.91 0.66 0.76 0.86 V 0.60 0.70 0.80 - 0.26 0.50 V most negative point in the external circuit to maintain isolation provide for between transistors and to normal transistor action. Magnitude of Difference in Qs, Vgg Magnitude of Oifference in Ir & 02 Matched V CE >6V, lc 1 mA - 0.5 5 mV - 0.2 3 uA •When used as a zener for reference voltage, the device musi not be subjected to more than 0.1 milhioule of energy from any possible capacitance or electrostatic discharge in order to prevent degradation of the junction. Maximum operating zener current should be less than 10 mA. fie. 2- 1/t noite figure at » function of collector current ar ^SOURCE " *"" "• 215 81 CA3127E DYNAMIC CHARACTERISTICS at T A CHARACTERISTICS - 2S°C LIMITS TEST CONDITIONS Min. l/F Noise Figure f Gain-Bandwidth Product Vce Collector. to-Base R$ = 100 kHz. Col lector lo-Subsirate V ct Capacitance Emitter-to-Base Capacitance Voltage Gain » 6 V, f- 1 - f 1.8 — dB mA - 1.15 — GHz MHz - See - pF - Fig. - pF 5 - PF dB V. f - VcE "6 V, f > 10 kfi. 1 1 MHz 1 VBE »4 R|_" mA - 500 n, lc - - 6 V. lc • 5 VCB"6V. Capacitance - 1 UNITS Typ. Max. MHz 3— Fig. /// noite figure as j function of collector current et R SOURCE • ' *U MHz Ic'ImA - 28 - 27 30 _ i co*.tic*o«- -0 Cascode Configuration Power Gain f- 100 MHz. V+- 12 V Noise Figure IC • mA - Input Resistance Common- Emitter — 1 Output Resistance Configuration Input Capacitance VC E Output Capacitance IC - Magnitude of Forward f mA 2 — — — — 24 - 400 4.6 3.7 - MHz » 200 - 3.5 — — V 6 1 . Transadrnittance (•>!(• .oi.ft.ci i^ii*** jjli:l::!:!:|:J rJB dB n ktt pF pF mmho 4 — Gembendxrrdth product Fig. it t function of collector current __ -f r JLZZ ^ *s •• >rt _ 1!- 1 - I" } ,: I "I 1: I I Cmmm wojf i I * i r •• - —— e co hmmm ^£"i-* •V I SI «iMft«a- ro-c*W l~^^" ' .J, « I • 0.ts»- to^emitter voltage si e function of ^'9- 67*W i • •» vOt'**l - Capacitance voitagm for collector current. — 1 t>« - • at j function »«1 m* . ,0 »» 1 « *° ! , 1 < 07*» pn 3 1*' ••» «7« — O \m 018 • MO IN V 1 "0 0*10 '» B • «o < n 1 f f » MHi. Guard terminal! except thote un*Jer test. •» couict a* / ZLujLU- T f*M MR (tan 1 Typical capacitance values at Three termntef measurement eft » 7W V • OK «7* a i*i -36 C0u.tC»O»-'0-|»»»'t« *X'*** "*c !•» ta*o •« %-wv.t i«\.iooo •OO ()* ' •(>' :i* ' « TO U •• -o lOMltO '•ft r <*(!••• -1L 3 ' 1 « « . 1 "! 1 TT 1 -« .1 '',1-1 1 / - Voltmq* tt R. NTH j.. ... — ,\Ji 1 < ^'^. "~~ *-* i' 1 , | i 1 5 67tW fljp Q} 1 ; tf of bias TO n OS '-' ^i~i±J±.L. I 04 r ..\..- /.\7\t*»*<.it»mc.l ic<#' - 77* 97r» • DON 03 • no CO • 07 C(»j T* COttldOO-'O-O**! I j j C»»K'n«Cf 1 5 — «o "»0_ JSL 0* Fig, « to «Cf gun 100 L_L» -U ji • II - !. 1 function of frequency 101 ^/». J - vmiiq* it a. - fttm »« • function ol frequency 1 *il 82 f«0. ^ - DC KbVOWoTol tVHIM tre*ufr+ rstiO *« # function of collector current. CA3127E TmoXCM Tf MVCMruM couccioa- ro-CMirrta • tl 4 ri *<•>'»< <n**t»tli#( l«lvC .on«d — ' i a i.« » 1!;; :i!:,:uj 1 ':^!:TH:r-j:fcrtW:ttKit!fc«i:* _ 8. ., . . , _ <- ,_ :i::! :• :: ~ l _ ., UI'D't i ii !»«<••« CQLLCCtM CUMCHrdcl- •• '•* / '° 1 •.:•:•• 7 ii ; i ii ,/ » 1 V -3*^ 0« rfm ri 01 1 ' ! • : /I « I t i O c oo - topur admittance 1Y , racMacrtn— m CaUSCIM CuMCNf H C I-*A rfOuCMv If I— NM ffl . 'I ^* "Til * M A/ y/ S* sr j 0, I fca, i / *yr 1 * / J jj * function of fry. " — freQuency. /npuf admittance (Y j MB>RM j) as a function of A'o; /«? — Output admittance (^22* ** * function of frepuency. collector current. f|i**-.*fti.»| if A wvt COIIIC' COLttCl 0* (U««(»t .\lMtft* " 1 *> * » : — 3 h Vfti ii — - * 'jo 3 1 Si m fO » O " ^td_ M 5 1 ! c 3 » oo 7 caucfvicuMfiititci—« fit. /J - Output admittance \Y22i M( . mM ' 000 J 'ltM«'(l!-« o 1 collcctc* cu««t*riic>— •* Mct'tfin as * 'uflC " on "' Fig. 14 - Forward trensadmittance (Y2ft collector current. es a fioj function of collector current. WKim '"M*: • > i riw 1T4M! c voitl Stnt CW.L(Cr<J*-f K»«M /5 - forward transadmittance IY21I at a function of frequency. |l« IV •0 J ? 4/0 I i 3 *04 i Of t5 vAj • 0* : *•*. g8 S* si s - j 1 0*.'. - - „ -jo* <T) 1 —— •iCi ) "! T M Ml 1 «»o»* <^ I/O 1 "' 1© °."» FI»fQuC«CTiM— «•*• % ft? - Reverse trensadmittance (Yj2* function of collector current. Kft*Wfk F «* Fig. • 17 - reverse trensadmittance IY 12) at a function of frequency. Fig. 18 — Voltage-gain test circuit using current- mirror biasing for Q2. — —-h This circuit was chosen because it convenieoMy represents a close appro hi mat on in i>erformance to properly unrlateralizerj single transistor of this type. The use 0* Q3 in a current-mirror configuration facilitates simplified biasmq. The use of the cascode circuit in no way implies that the transistors cannot be used individually. , frrr: a I 1 11(1 Fig. Fig. 19 - 100MHz power-gain end noise- figure test circuit. 20 — Block diagrams of power-gain and figure test setups. 83 irno noise- APPENDIX C MOTOROLA MC1488 QUAD LINE DRIVER DATA SHEETS SY30T<GFZ€2LA MC1488 QUAD MDTL QUAD The MC1488 LINE DRIVER RS-232C SILICON MONOLITHIC INTEGRATED CIRCUIT LINE DRIVER a monolithic quad line driver designed to interequipment with data communications equipment in conformance with the specificationsof EIA Standard No. RS-232C. ii face data terminal Features: • Current Limited Output tlOmAtyp • Power-Off Source Impedance 300 Ohms min 1L • Simple Slew Rate-Control with External Capacitor • Flexible Operating Supply • Compatible with All Motorola CERAMIC PACKAGE CASE 632-02 MO-001AA Range MOT L and MTTL 1" SUFFIX P SUFFIX PLASTIC PACKAGE CASE Logic Families PIN CONNECTIONS TYPICAL APPLICATION uftt omvfil inffiicotnfCTiNlI •Out u»( icnvm CUM CAilt ..HZ)* "oiiioeiciwur • •onioeicoufnii CIRCUIT SCHEMATIC OF CIRCUIT SHOWNI 11/4 *vs MOTOROLA LINEAR/INTERFACE DEVICES 5-114 84 O purrut 646-05 MC1488 MAXIMUM RATINGS »25 C unless otherwise noted .) IT A • Symbol Rating Power Supply Voltage vcc VEE Input Voltage Range V|R Output Signal Voltage vO - • 1'"»JA . Storage Temperature Range ELECTRICAL CHARACTERISTICS (Vcc - +9.0 * 10% Vdc, Low Figure Input Current High Logic Slate Logic State (V|(_ = 0) V|n I • 5 V) Output Voltage - High Logic Slate (V| L "08 IV|l 8 3 0klJ. Vdc. Ri_ RL Vclt. " VCc 3 0kiJ. Vdc V EE " *9.0 Vcc * , ' > 3 2 Vdc. V EE Output Vottjge Low Logic Slate (V| H 1 9 Vdc. R L * 3.0 kfi, Vcc * *9-0 Vdc V EE ^ IV| H « 1.9 Vdc. Positive RL" 3 ki>. Vcc " * Output Snort Circuit Current Positive IV|H " 1.9 Vdc. 8 Vdc. (V| L « Vcc VC C VC c • 19 Vdc. (V, L • 08 Vdc. IV|H 19 Vdc. Vcc Vcc 8 Vdc. VC c IV|h V EE * Supply Current (R| * IV| L • " 1 IV| L • VE g 19 Vdc. Vgg 0.8 Vdc.Vgg (V| H • 19 • Vg | - *2 '90 Vdc) ' ,9 * »12 Vdc) " *12 Vdc " °C °C - 75'C unless otherwise noted.) Typ 1 6 1 V H '9 '105 -6.0 -7 (lA Vdc 3 'OS* '6 • 3 'OS- -6 -10 10 300 o - -105 -9.0 r mA 7 V OL 4 Unit Vdc 2 vdct VI Ma. 10 ° vdcl " " ,3 to Mm Symbol if. 12 mA -12 inA • Ohms - mA 'cc 15 20 4.5 60 • ° vdcl 19 - ' 5.5 ,s Vdc) 25 7 •34 '15 Vdc) •17 <x* 5 >EE -13 a «.-9.0 Vdc) < - -12 Vdc) -18 -17 mA -15 MA -23 mA -12 Vdc) -15 „A Vgg -15 Vdc) -34 <V ft_ • 0.8 Vdc. V EE -15 Vdcl -2 5 mA mA Vdc. • Power Consumption IV c c 9 Vdc. V E g --9 Vdc) IV C c * 12 Vdc. V EE • -12 Vdc) Propagation Delay Time Fall Time (i| Propagation Oelay Time Rise Time Maximum li| • tti • In (V C c- + 9 0±1% Vdc. V EE • -9.0+ 1% Vdc. T A ISpFI 6 and IS pF) 6 3.0 k and 15 pF) 6 and 15 pF) 6 3.0 k and * 3 • 3 k k mW "C SWITCHING CHARACTERISTICS (1) Oto *75 'IH 5 * " * | V E£ mW mW/°C -65 to »175 1 2 * "9 Vdc T «.g -13.2 Vdc) 11 1 9 Vdc. V EE - -9.0 Vdc) IV (L -0.8 Vde. (V|h 0. - • Vdc 7 60 ao) Negative Supply Current IR^ IV|H - - 6 . "90 Vdc) (11 Negative Output Short Circuit Current Output Resistance (Vcc 13 2 vde " < 70 TA 1 2 Vdc 115 V EE - -9.0 i 10% Vdc, T A = Characteristic Input Current - 15 -15 1000 «25°C Ooerating Amtnent Temperature Range Unit 15 < V, B Power Derating (Package Limitation, Ceramic and Plastic Oual-ln-Lme Package) Derate above T A Value Package Power Dissipation may be exceeded if all - • - 275 350 ns - 45 75 ns <PHL - 110 175 ns H - 55 100 ns 'PLH 'THL tTI MOTOROLA LINEAR/INTERFACE DEVICES 85 333 576 25°C.) outputs are shorted simultaneously. 5-115 - . MC1488 CHARACTERISTIC DEFINITIONS FIGURE 1 sv - INPUT CURRENT -j FIGURE - OUTPUT VOLTAGE 2 -»V •*V v IJV VOL VQH •OIV FIGURE 3 - OUTPUT SHORT CIRCUIT CURRENT vce • FIGURE 4 - OUTPUT RESISTANCE (POWER-OFF) *M IJV •0S- ftl 6 'OS* mA Mti •OIV FIGURE 5 FIGURE - POWER-SUPPLY CURRENTS 6 - SWITCHING RESPONSE -»V„ •IJV ^ISpF Jl I „jfF v •OIV \ -0V 'PIH - SOX ITMl -'TLH rTHl •"< <TLH v« MOTOROLA LINEAR/INTERFACE DEVICES 5-116 86 Ko»« 10% l» 9CT% MC1408 TYPICAL CHARACTERISTICS (Ta * +25°C unless otherwise noted.) 7 - TRANSFER CHARACTERISTICS hiui POWER-SUPPLY VOLTAGE FIGURE 12 • FIGURE < a 1 l?V \ 1 o bU EE" Vi O p- £ -3 _ t-L> £. o 3 OB 5 £ a 3 -30 » Vcc '9 V V| • _y* 1 en y ^_ -9 1 • 3 ° s.o 19V 1 > I 3 U >v 1 < '0S* Hi 1 1 «I2 .90 z 1 \ V C C'VEE'i9V P"» - SHORT-CIRCUIT OUTPUT CURRENT vanus TEMPERATURE 1 • 8 u 0,V JL 1vee-9V -6.0 IQS- -go it* -12 -12 2 4 0.6 Vi„.INPUT 12 10 0.8 1.4 1.6 1 I T.TEMPERATURECC) VOLTAGE (VOLTS) OUTPUT SLEW RATE FIGURE 10 - OUTPUT VOLTAGE LIM! TING CHARACTERISTICS ANO CURRENT mui LOAO CAPACITANCE 20 16 < V\ as u 1 ,, -12 5Z vcc-v Ef 1.000 C|.. CAPACITANCE -80 10.000 9\ ' -40 -MAXIMUM OPERATING TEMPERATURE 11 VOLTAGE 16 14 'cc 12 a V 1 3k 3 10 1.0 N — 6 3k > 3k II 3k 60 40 k - i, 20 \ —\ '0 -L. -40 Vq. OUTPUT VOLTAGE (VOITSI venut POWER-SUPPLY < \ _j <pf| FIGURE t J_ -55 J W5 »2S T. TEMPERATURE 125 (OCI MOTOROLA LINEAR/INTERFACE DEVICES 5-117 87 / _e- \ ~V0S — M! L0AO LINE. - \ 19V •20 100 \ -\ h:-J^t . -6 —— v\ p- 10 •125 *»5 »25 -55 2 -80 .12 MC1488 APPLICATIONS INFORMATION FIGURE 13 - POWER SUPPLY PROTECTION TO MEET POWER-OFF FAULT CONDITIONS The detail Electronic Industries Association (EIAI RS232C specification the requirements for the interface between data processing equipment snd VCC ± communications equipment. This standard specifies not oniy the number and type of interface leads, but also the voltage levers to be used. The MCI 488 quad driver and its companion circuit, the MC1489 quad receiver, provide a complete interface system between OTL or TTL logic levets and the RS232C defined levers. The data RS232C requirements 1 1 -0 »4-i. .--' for •- » 1 1 "1". -c 1 1 MC1488 is much FOR Isc versus 10 -I. _• 1 •o 1 1 1 L H too — FIGURE 12 - SLEW RATE "\ 1 1 specification further requires that during transitions, the driver output slew rate must not exceed 30 volts per microsecond. The inherent slew rate of the r - O-T - s Oi- The RS232C 1 i CAPACITANCE mA would he excessive Therefore, if the system is designed to permit low impedances to ground at the power supplies of the drivers, a diode should be placed in each power-supply lead to prevent overheating m this fault condition These two diodes, as shown in Figure 13. could be used to decouple all the driver packages in a system. (These same diodes will allow the MCI 488 to withstand 1000 momentary '00 Standard shorts to the RS237B I »25voH The addition limits specified in the earlier of the diodes also permits the MCI 488 to withstand faults with power-supplies of 9.0 volts stated above. * — o-t-T" **\ 15- These voltages ere so defined when the drivers ere terminated with a 3000 to 7000-ohm resistor. The MC1488 meets this voltage requirement by converting a OTL/TTL logic level into RS232C levels with one stage of inversion. a i. CI 481 O-f-O as applied to driven are discussed herein. The required driver voltages are defined ef between 5 and volts in magnitude and are positive for a logic "0" and negative a logic 6,. — MC14M MC14J8 less than the The maximum short-circuit current -allowable under fault con is more than guaranteed by the previously mentioned difions io 10 niA output current limiting Other Applications The MC1488 is an extremely versatile line driver with of possible applications a myriad Several features of the drivers enhance this versatility: 1 Output Current Limiting - this enables the circuit designer output voltage levels independent ol power supplies and can be accomplished by diode clamping ol the output pins Figure 14 shows the MC1488 used as a OTL to MOS tremlator where the high-level voltage output is clamoed one diode above ground The resistor divider shown is used to reduce the output voltage below the 300 niV above ground MOS input iPrjsN Innri to define the fast for this requirement The current limited output of the device can be used to control this slew rate by connecting a capacitor to each driver output The required capacitor can be easily determined by using the relationship C 'OS * •iT/.W from which Fiqure I? is derived Accoidmqiy. a 330 |iF capacitor on each output guarantee a worst case slew rate of 30 volts per microsecond The interface will driver is also required to withstand an accidental short to any other conduc tor in an interconnec ting cable. The worst on any conductor would be another driver using a plus or minus 15-volt. 5O0-mA source The MC1488 is designed to possible signal indefinitely withstand such a short to all four outputs in a package power-supply voltages are-greater than 9 volts d e., V CC?9 V; V EE< -9 vl ln some power-supply designs, a loss of system power causes a low imoedance on the power suoply outputs. When this occurs a low impedance to ground would exist at as long as the the power inputs to the MC1488 output lesistors to ground to plus or minus IS If volts, the all effectively shorting the 300-ohm four outputs were then shorted power dissipation in these resistors 2 Power Supply Range as can be seen liom the schematic drawing of the drivers, the positive an<i negative driving elements of the device are essentially. independent and do not iequire match ing power supplies. In fact, the positive supply can vary from a minimum seven volts Irequired lor driving the negative pulldown secttoni to the maximum specified 15 volts. The negative supply can vary from approximately -2 5 volts to the minimum speolied -IS volts. The MC1488 will drive the output to within 2 volts of the positive or negative supplies as long as the current output limits ere not exceeded The combination of the current limning and supply voltage features allow a wide combination of possible outputs within the same quad package Thus if only a portion of the four drivers are used for driving RS232C 'mes. the remainder could be used for OTL to MOS or even OTL to OTL translation Figure IS shows one such combination MOTOROLA LINEAR/INTERFACE DEVICES 5-118 88 KC1488 FIGURE 14 - MOTL/MTTLTOMOS TRANSLATOR FIGURE IJV 1/4 Mni«—-\ input <—i INPU - LOGIC TRANSLATOR APPLICATIONS i*-0 MOTl f IS ? ~T T * MRTl OUTPUT -o ; v io 'i i V "T T * MOTL OUTPUT -0 7 V io <i 7 V MCM88 MOS OUTPUT WITH Vss-GNOI —'Jo- •>' 5V — MIITlOUIPur -o; V -12V •12 in 10 V V 1 10 k MOTOROLA LINEAR/INTERFACE DEVICES 5-119 89 MOS OUTPUT -IOVioOV LIST OF REFERENCES 1. Powers, J. P., AN INTRODUCTION TO FIBER OPTIC SYSTEMS Course Notes Naval Postgraduate School, 1986. . 2. Wolf, H.F. and others, HANDBOOK OF FIBER OPTICS j_ THEORY AND APPLICATIONS p. 412, Garland STPM Press, 1979. . 3. Roberts, H. and Rando, J., "WDM ACTIVE COUPLER FACILITATES BIDIRECTIONAL TRANSMISSION", LASER FOCUS, V.22, p. 100, APRIL 1986. 4. Stone, H.S., MICROCOMPUTER INTERFACING Co., Inc., 1983. 5. Gofton, P.W. Inc., 1986. 6. Sever, M.D., RS232 MADE EASY 1984. 7. ADC FIBER OPTIC TRANSCEIVER EVALUATION KIT INSTRUCTION MANUAL, ADC Fiber Optics, 1986. 8. HP82939A Serial Interface Owner / s Manual Series 80 Hewlett-Packard Co., Inc., 1982. 9. SPINWRITER 7700 Terminals Product Description Information Systems Inc., 1981. , , Addison-Wesley Mastering Serial Communications . . SYBEX Prentice-Hall Inc., . . NEC 10. AMPEX 210 Video Display Terminal Operation Manual AMPEX Corporation, Computer Products Division, 1984. 11. Motorola Linear Interface . Inc., /_ Linear Devices . Motorola 1987. 12. Photodvne 13. Connector i zed Active Bi-directional Coupler Data Sheet p. 2, ADC Fiber Optics, 1986. 14. Electronic Measurement Design Computation Catalog p. 136, Hewlett-Packard Co., Inc., 1987. 2 2XLA Manual , p. 90 iv, Photodyne Inc. , , 15. ODL RS232 Fiber Optic Modem Preliminary Data Sheet ATT, 16. 1986. Ormond, T., " Military Fiber Optic Components EDN .v.32. pp. 114-125, August 20 1987. 91 ", , INITIAL DISTRIBUTION LIST No. Copies 1. Library, Code 0142 Naval Postgraduate School Monterey, California 93943-5002 2 2. Defense Technical Information Center Cameron Station Alexandria, Virginia 22304-6145 2 3. Department Chairman, Code 62 Department of Electrical' and Computer Engineering Naval Postgraduate School" Monterey, California 93943-5000 5 4. Professor S. Michael, Code 62Mi Department of Electrical and Computer Engineering Naval Postgraduate School Monterey, California 93943-5000 1 5. Lieutenant James W. Ryan, USN 37 Rock Avenue Lynn, Massachusetts 01902 2 92 1 8*7 6 7 M01J 5002 tion of a ??i. impleiae nta° ptic RS23 2 link. • Thesis R9445 c.l Ryan Design and implementation of a fiber optic RS232 link.