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TR41.3-07-05-003b NIPP – Network, Interfaces, Power and Protection NIPP-NAI – Network Access Interfaces Nashville, TN February 12 - 16, 2007 NIPP-NAI-2007-036R1 CONTRIBUTION TITLE: SOURCE*: PROJECT: Remote End POTS Splitter Requirements Editor1 Splitters _______________________________ ABSTRACT This contribution outlines the requirements for static splitter testing regarding ADSL and VDSL splitters. Splitters are used for protection of typical POTS devices when ADSL or VDSL services are deployed on the same copper pair. This revision is a result of the input gathered at the Nashville, TN meeting, February 12 – 14, 2007 along with specific changes outlined by contributions NIPP-NAI-2006-150R1, NIPP-NAI-2007-003, NIPP-NAI-2007-005, NIPP-NAI-2007-032, and NIPP-NAI-2007033. This contribution contains updates to NIPP-NAI-2006-079R2 agreed to by this subcommittee. The exact changes are reflected in living list NIPP-NAI-2007-028R1. R1 of this document contains un update to section 4.7.3. In the original version the section was incorrectly titled DSL to Line insertion Loss. The correct VDSL Non-Linear Distortion titled has been added. It is the intent of the subcommittee to utilize this contribution for letter ballot as quickly as possible. _______________________________ 1 CONTACTS: Christian Duran; Corning Cable Systems; [email protected]; Tel: 817-337-7230; Fax: 817-431-7554 Erin Blake; Corning Cable Systems; [email protected]; Tel: 817-431-7306; Fax: 817-431-7554 Page 1 of 24 TABLE OF CONTENTS 1 SCOPE AND PURPOSE ......................................................................................... 5 1.1 1.2 1.3 SCOPE ........................................................................................................................... 5 PURPOSE ...................................................................................................................... 5 OTHER CONSIDERATIONS ......................................................................................... 5 2 REFERENCED STANDARDS ................................................................................ 6 3 DEFINITIONS, ABBREVIATIONS, ACRONYMS AND SYMBOLS ......................... 7 3.1 3.2 4. REMOTE END SPLITTER REQUIREMENTS ......................................................... 9 4.1 4.1.1 4.2 4.2.1 4.2.2 4.3 4.4 4.5 4.5.1 4.5.2 4.6 4.6.1 4.6.2 4.6.3 4.7 4.7.1 4.7.2 4.7.3 5. DEFINITIONS................................................................................................................. 7 ABBREVIATIONS, ACRONYMS AND SYMBOLS ........................................................ 7 INTRODUCTION ............................................................................................................ 9 Remote End Splitter Function Location ................................................................................... 9 TEST REQUIREMENTS .............................................................................................. 11 Frequencies Used in Testing-Test Requirements ..................................................................11 Balanced Terminations ..........................................................................................................12 ZHP-R AND ZNL-R IMPEDANCES DEFINED ............................................................ 12 MAINTENANCE TEST SIGNATURES (MTS) ............................................................. 12 SIGNALING REQUIREMENTS.................................................................................... 13 Applied Ringing Signals .........................................................................................................13 DC Resistance .......................................................................................................................14 VOICE BAND REQUIREMENTS ................................................................................. 15 Metallic Balanced (Differential Mode) .....................................................................................15 POTS to Line Longitudinal Balance .......................................................................................18 Transparent Testing Capacitance ..........................................................................................19 VDSL BAND TESTING ................................................................................................ 20 DSL Band Attenuation ............................................................................................................21 DSL to Line Insertion Loss .....................................................................................................22 DSL to Line Insertion Loss .....................................................................................................22 INFORMATIVE REFERENCES............................................................................. 24 Page 2 of 24 TABLE OF FIGURES Figure 4-1: Structure of remote end DSL splitter ............................................................................ 9 Figure 4-2: NID deployed remote end splitter .............................................................................. 10 Figure 4-3: Ancillary remote end splitter ....................................................................................... 10 Figure 4-4: Remote end splitter located inside the home ............................................................. 11 Figure 4-5: Remote end splitter located inside the modem .......................................................... 11 Figure 4-6: ZHP-r of DSL port termination for voice band testing ................................................ 12 Figure 4-7: ZNL-r of POTS port termination for voice band testing .............................................. 12 Figure 4-8: Maintenance test signature ......................................................................................... 13 Figure 4-9: Transmission measurements in the voice band ........................................................ 17 Figure 4-10: POTS to line return loss measurement .................................................................... 18 Figure 4-11: POTS to line longitudinal balance measurement per IEEE 455 .............................. 19 Figure 4-12: Capacitance measurement ...................................................................................... 20 Figure 4-13: DSL band attenuation measurement ....................................................................... 22 Figure 4-14: VDSL to line insertion loss measurement ................................................................ 22 Page 3 of 24 TABLE OF TABLES Table 4-1: POTS to line insertion loss requirements ..................................................................... 15 Table 4-2: Attenuation distortion requirements ............................................................................. 16 Table 4-3: POTS to line group delay requirements ....................................................................... 17 Table 4-4: POTS to line return loss requirements ......................................................................... 17 Table 4-5: POTS to line intermodulation distortion requirements ................................................. 18 Table 4-6: POTS to line longitudinal balance requirements .......................................................... 19 Table 4-7: Profile frequency minimum and maximum ................................................................... 20 Table 4-8: DSL band attenuation requirements ............................................................................ 21 Table 4-9: VDSL to line insertion loss requirements ..................................................................... 22 Table 4-10: Remote End VDSL2 splitter intermodulation test parameters ................................... 22 Page 4 of 24 Remote End POTS Splitter Requirements 1 SCOPE AND PURPOSE 1.1 SCOPE This technical requirement document defines a minimal set of static electrical requirements for a remote end splitter. The parameters defined include terminations, frequencies, testing, test signatures, dc characteristics, voice-band characteristics, attenuation, envelope delay distortion, impedance, longitudinal balance, and metallic balance. Additional features and performance characteristics such as dynamic testing are beyond the scope of this document. Dynamic testing of a splitter is performed in a live POTS and xDSL modem environment. This includes, but is not limited to, a complete system setup using CO and remote splitters, xTU-C and xTU-R modems, CO ringers and a telephone. Performance of the splitter is measured by evaluating the Layer 1 primitives reported by the xTU-C and xTU-R (CRCs, FECs, etc.) during on-hook, off-hook, ringing, and ring trip events. This work is being covered by the DSL Forum. The reader should note that implementations addressing the applications described herein may also be subject to other industry specifications such as TIA-968-A, GR-1089-CORE, and UL documents. 1.2 PURPOSE This technical requirement document is intended to facilitate the provisioning of various digital subscriber line (DSL) technologies and voice band services over the same loop. The document is written broadly to permit the remote end splitter to be used for current DSL technologies and potential new DSL technologies that use the same frequency spectra. 1.3 OTHER CONSIDERATIONS Network systems apply various electrical signals to the subscriber loop for the purpose of network maintenance and alerting the customer of an incoming call. These signals vary considerably in amplitude and can reach values of -/+ 200Vdc for maintenance functions and 276.2 volts peak for alerting signals. When these signals are applied to an access line that also has a remote end splitter wired in series with the subscriber loop, the low pass section of the splitter may see the full magnitude of these signals. Therefore consideration should be given to the selection of circuit components used for the splitter design. During the times these signals are applied, it is acceptable that the low pass filter does not perform all of its functions nor meet all of the technical requirements in this document. However the filter components should not be permanently damaged. Such phenomena as lightning and over voltage due to inductive interference or power cross lie beyond the scope of this Technical Requirements document. The detailed technical parameters of the network maintenance, alerting signals, and safety referenced here can be found in the informative references in Section 5. Page 5 of 24 2 REFERENCED STANDARDS The following standards contain provisions that, through reference in this text, constitute provisions of this technical requirements document. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this document are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. [1] ANSI T1.413 - Network and Customer Installation Interfaces – Asymmetrical Digital Subscriber Line (DSL) Metallic Interface, Committee T1-Telecommunications, 1998. [2] ANSI T1.417 - Spectrum Management for Loop Transmission Systems – 2001 [3] ATIS T1.TRQ.PP.10-2003 – Splitters used for Line Splitting and Line Sharing Applications 2003 [4] ANSI T1.424-2004 - Interface Between Networks and Customer Installations – Very-High Speed Digital Subscriber Lines (VDSL) Metallic Interface - 2004 [5] IEEE Standard 455 - IEEE Standard Test Procedure for Measuring Longitudinal Balance of Telephone Equipment Operating in the Voice Band, 1985 or later. [6] IEEE Standard 743 - IEEE Standard Equipment Requirements and Measurement Techniques for Analog Transmission Parameters for Telecommunications, 1995. [7] Telcordia Technologies GR-57-CORE Issue: 01 2001-10-19, Functional Criteria for Digital Loop Carrier Systems [8] Telcordia Technologies GR-506-CORE Issue: 01 1996-00-00, - LSSGR: Signaling for Analog Interfaces [9] ITU-T G.993.2; Series G: Transmission Systems and Media, Digital Systems and Networks, Digital transmission systems - Access networks, Very high speed digital subscriber line transceivers 2 (VDSL2) Page 6 of 24 3 DEFINITIONS, ABBREVIATIONS, ACRONYMS AND SYMBOLS 3.1 DEFINITIONS Narrow band services Services that use a small portion of the 0Hz to 4 kHz frequency band. Splitter A network comprised of frequency-domain filters that separate the highfrequency DSL signals from the voice-band signals, at the respective ports (DSL and POTS) (frequently called POTS splitters even though the voice-band signals may comprise more than voice). Sub-voice band The 0Hz to 200Hz frequency band. Voice band The 200Hz to 4 kHz frequency band. Voice band services Services that use the 300Hz to 4 kHz band or a major portion of it. 3.2 ABBREVIATIONS, ACRONYMS AND SYMBOLS ADSL ADSL+ ATM BB caps CO CPE DAML DC DCR DSL DSLAM ERL FDI HB HDSL HPF LB LPF mA MDF NB NID nF POTS PSTN RL rms RT SAI SDP SDSL SFRL SHDSL asymmetric digital subscriber line asymmetric digital subscriber line with higher available bit rates asynchronous transfer mode broad-band capacitors central office customer premise equipment digital added main line direct current direct current resistance digital subscriber line digital subscriber line access multiplexer echo return loss feeder distribution interface high-band high bit-rate digital subscriber line high-pass filter longitudinal balance low-pass filter milli-amp main distribution frame narrow-band network interface device nano-Farad plain ordinary telephone service public switched telephone network return loss root-mean-square remote terminal serving area interface subscriber demarcation point symmetrical digital subscriber line single frequency return loss symmetrical high bit-rate digital subscriber line Page 7 of 24 SRL-Hi SRL-Lo TU-C TU-R U-C uF U-R usec VDSL xDSL ZNL-r ZHP ZHP-r ZTC ZTR singing return loss high singing return loss low DSL transceiver unit, central office end DSL transceiver unit, remote end “U” interface – central office end micro Farad “U” interface – remote end microsecond very high bit-rate digital subscriber line types of DSL such as ADSL, ADSL+, HDSL, SDSL, SHDSL, or VDSL non-loaded cable compromise impedance as seen from the remote high-pass filter impedance high-pass filter impedance of TU-R network terminating impedance remote telephone terminating impedance Page 8 of 24 4. REMOTE END SPLITTER REQUIREMENTS 4.1 INTRODUCTION A service splitter is required at both ends of the line that carries DSL signals if existing narrowband services are to remain unaffected by the presence of DSL signals on the same wire-pair. The requirements for a service splitter at the remote customer side are defined in this clause. The term ‘splitter’ could be interpreted to include both a high-pass filter for the DSL, and a lowpass filter for voice. It should be noted, though, that most implementations of a remote-end ‘splitter’ do not include the high-pass filter functionality. Such functionality is typically implemented in the DSL transceiver. 2 The structure of the remote end splitter is given in Figure 4-1. The DSL port connects to the DSL transceiver. The POTS port shall connect to the existing voice band equipment. The POTS-toLINE port function is that of a low-pass filter. Certain isolation is required between POTS and DSL ports to prevent undesirable interaction between DSL and the used narrow-band service. The remote end DSL splitter requirements guarantees the proper operation of POTS on lines that carry DSL signals. POTS PORT LPF LINE PORT DSL PORT Figure 4-1: Structure of remote end DSL splitter The remote end DSL splitter shall meet the requirements with all DSL transceiver impedance values that are tolerated by its return loss specification. 4.1.1 Remote End Splitter Function Location The remote end splitter can be located in four different locations, the NID, next to the NID, inside the home, or inside the TU-R. 4.1.1.1 Splitter Located in the NID Figure 4-2 shows the splitter when it is incorporated in a NID. 2 This document does not prohibit the inclusion of the high-pass filter functionality in the splitter. Page 9 of 24 PSTN NID CO Splitter POTS & DSL POTS LPF Primary Protector TU-R LOOP LPF MODEM Remote End Spliter POTS DATA Figure 4-2: NID deployed remote end splitter 4.1.1.2 Splitter Located Next to the NID Figure 4-3 shows the splitter when it is located in an ancillary position to the NID. PSTN NID CO Splitter POTS & DSL POTS LPF Primary Protector TU-R LOOP MODEM LPF Remote End Splitter DATA POTS Figure 4-3: Ancillary remote end splitter 4.1.1.3 Splitter Located Inside the Home Figure 4-4 shows the splitter when it is located inside the home. Splitters inside the home are usually installed in a central location. Depending on the particular subscriber home wiring a subscriber may be adept enough to install a splitter in the home. Page 10 of 24 PSTN NID TU-R CO Splitter POTS & DSL POTS LPF Primary Protector LPF Home Remote End Splitter LOOP POTS MODEM DATA Figure 4-4: Remote end splitter located inside the home 4.1.1.4 Splitter Located With the TU-R Modem Figure 4-5 shows the splitter when it is implemented with the TU-R modem. This configuration is very similar to the splitter located inside the home. The TU-R with integrated splitter will be installed in a central location so as to route the necessary internal CPE wiring. PSTN NID CO Splitter TU-R POTS & DSL POTS LPF Primary Protector LOOP LPF Integrated Remote end Splitter POTS MODEM DATA Figure 4-5: Remote end splitter located inside the modem 4.2 TEST REQUIREMENTS 4.2.1 Frequencies Used in Testing-Test Requirements Two bands of frequencies shall be used for testing; voice band and DSL band. Testing shall not be performed between 4 – 25 kHz but it is expected that the LPF shall be well behaved in this area (i.e., the amplitude response is monotonically decreasing from 4 to 24 kHz) Page 11 of 24 4.2.2 Balanced Terminations All testing shall be done in a BALANCED (i.e. metallic) method. Test equipment with unbalanced connections may be used as long as the resultant measurement maintains balance. Balun transformers are often used on test equipment with unbalanced connections. 4.3 ZHP-R AND ZNL-R IMPEDANCES DEFINED To facilitate testing of the DSL splitter independently of the actual modem or specific vendor, ZHP-r is defined to allow proper termination of the DSL port during voice band testing for the splitter at the remote customer end. (See Figure 4-6) The ZHP-r is valid only for voice band frequencies. ZNL-r is defined as lumped impedance models of loops for remote-end splitter design. The requirements for ZNL-r are shown in Figure 4-7. 0.10 µF 0.12 µF 100 Ohm 0.10 µF 0.47 mH 0.12 µF Component Tolerances Capacitors = 2.5%, Resistors = 1%, Coils = 5% Figure 4-6: ZHP-r of DSL port termination for voice band testing 348 Ohm 1300 Ohm 100 nF Component Tolerances Capacitors = 2.5%, Resistors = 1% Figure 4-7: ZNL-r of POTS port termination for voice band testing 4.4 MAINTENANCE TEST SIGNATURES (MTS) If the maintenance test signatures are provided for the remote-end splitter, they shall be as shown in Figure 4-8. In order to allow the DSL splitter to be managed by the network operational support systems and to be identified by metallic loop test systems, the remote end DSL splitter function may contain a signature that is activated by the metallic test systems. The signature is unique for all North Page 12 of 24 American remote end VDSL/ADSL splitters. The signature is designed to be active only during the maintenance mode and will not interfere with normal operation of the circuit. The signature is located on the POTS side of the LPF function protecting the DSL band frequencies from the nonlinear effects of the diodes. Tip 0.47 µF, 10% 6.8V, 10% 33 kOhm , 1% Ring Figure 4-8: Maintenance test signature 4.5 SIGNALING REQUIREMENTS Unless otherwise noted, all of the requirements in this standard shall be met in the presence of all of the following: POTS loop currents from 0 mA to 100 mA; POTS tip-to-ring DC voltages of 0 VDC to -60 VDC; POTS ringing signals that meet the criteria in 4.5.1. Compliance with the loop current range above may be demonstrated by meeting the requirements of this standard with loop currents of 0, 20, 40, 60, 80 and 100 mA (+/- 1 mA for all values) with a -50 VDC +/- 1 VDC source. Compliance with the DC voltage range above may be demonstrated by meeting the requirements of this standard with DC voltages of 0, -20, -40, and -60 VDC (+/- 1 VDC for all values) with 40 mA +/- 1 mA of loop current. 4.5.1 Applied Ringing Signals For the purposes of meeting the ringing signal requirement in clause 4.5, applied ringing signals shall meet the following criteria: The DC component of the ringing signal shall be between 0 VDC and -60 VDC. The AC component of the ringing signal shall be 20 Hz +/- 1 Hz; The AC component of the ringing signal shall have an open circuit voltage of 104 Vrms +/- 1 Vrms; The AC component of the ringing signal shall have a crest factor of 1.4142 +/- .01 The AC component of the ringing signal shall be applied for 2.0 seconds +/- 0.2 seconds and removed for 4 seconds +/- 0.4 seconds, then reapplied and removed for the same durations in a repeating pattern that lasts at least two minutes. Compliance with the applied ringing signal specified above may be demonstrated by meeting the requirements of this standard with the ringing signal characteristics specified above with a DC component of 0, -20, -40, and -60 VDC (+/- 1 VDC for all values). Page 13 of 24 There is no specification for AC current during ringing because the rms value is typically less than the DC current limit of 100 mA based on 104 VAC open circuit voltage and a five REN (1,400 ohm) load. During a ring trip event there is a possibility that a large amount of current can flow through the loop for a short period of time. Since the input of the majority of DSL low pass filters is inductive, there is a high probability that this high current will saturate the magnetic material of these inductive components. When saturation occurs, the inductive components will fail to operate correctly. This can result in loss of data for a short period of time and can lower the quality of service for video applications. Ring trip current can reach values of up to 1.0 Arms 4.5.2 DC Resistance The DC resistance from tip to ring at the POTS interface with the U-R interface shorted shall be less than or equal to 25 ohms. This requirement shall be met before and after all ring-trip events. The DC resistance from tip to ground and from ring to ground at the POTS interface with the U-R interface open shall be greater than or equal to 5 Mohms. Page 14 of 24 4.6 VOICE BAND REQUIREMENTS 4.6.1 Metallic Balanced (Differential Mode) 4.6.1.1 Test Loops Loops to be used for ADSL testing are divided into two groups. This is done to obtain more specific requirements under a widely varying conditions of short and long loops and to account for the effect the opposite splitter impedances being seen through the loop and effecting performance. Short Loops: 0, 0.5 Kft, 2.0 Kft, 5 Kft pairs of 26 AWG cables. Long Loops: ANSI T1.601 resistance design loops 7, 9, 13 and T1 TR28 CSA loops 4, 6, 7, 8. Loops to be used for testing of VDSL splitters are defined in Section 12.1 of T1.424-2004 4.6.1.2 POTS to Line Insertion Loss For each of the test loops specified in 4.6.1.1, the insertion loss from the source to the termination shall be measured with and without the splitter/ZHP combination inserted. The increase in insertion loss in the pass band on any of the test loops is due to the splitter/ZHP combination. The requirements are defined in Table 4-1. Figure 4-9 defines the test configuration that shall be used for all pass band insertion loss measurements for the remote end splitter. Table 4-1: POTS to line insertion loss requirements Splitter Loop ZTC (Ω) ZTR (Ω) Insertion loss (dB) Frequency (kHz) POTS Short ADSL Loops 900 600 < 1.0 1.004 POTS Long ADSL Loops 900 600 < 0.75 1.004 POTS All VDSL Loops 900 600 < 1.0 1.004 4.6.1.3 Attenuation Distortion in the Voice Band The defined ZHP shall be connected to the DSL port of the splitter (if the splitter is an internal part of the TU-R, then the modem remains connected as the DSL load). The attenuation distortion is the increase of loss over frequency relative to the insertion loss at 1004 Hz caused by the splitter/ZHP combination (or modem) measured in Figure 4-9. The requirements for attenuation distortion are defined in Table 4-2. Page 15 of 24 Table 4-2: Attenuation distortion requirements Splitter type Loop ZTC Ω ZTR Ω Insertion loss (dB) Frequency (kHz) POTS Short ADSL Loops 900 600 ± 1.5 0.2 to 3.4 POTS Short ADSL Loops 900 600 ± 2.0 3.4 to 4.0 POTS Long ADSL Loops 900 600 +0.5, -1.5 0.2 to 3.4 POTS Long ADSL Loops 900 600 +0.5, -1.5 3.4 to 4.0 POTS All VDSL Loops 900 600 ± 1.5 0.2 to 3.4 POTS All VDSL Loops 900 600 ± 2.0 3.4 to 4.0 NOTE: Attenuation is a positive value, gain is a negative value. POTS U-R U-C Remote End POTS Splitter POTS Test Equipment ZTR LINE Test Loop LPF DSL ZHP-r (Load) NOTES ZTC = 900 Ohm ZTR = 600 Ohm ZHP-r is the impedance presented to the POTS connection by a TU-R Page 16 of 24 ZTC Figure 4-9: Transmission measurements in the voice band 4.6.1.4 POTS to Line Envelope Delay Distortion The envelope delay distortion of the remote end splitter shall be measured using the test configuration of Figure 4-9. The increase in delay distortion caused by the remote end splitter as measured from the POTS port to the U-R interface, for each of the test loops specified in 4.6.1.1, shall meet the requirements of Table 4-3. Table 4-3: POTS to line group delay requirements Splitter Type Loop ZTC (Ω) ZTR (Ω) EDD (µs) Frequency (kHz) POTS All Loops 900 600 200 0.2 to 3.2 POTS All Loops 900 600 250 3.2 to 4.0 4.6.1.5 POTS to Line Return Loss The remote-end VDSL splitter shall meet the return loss requirements defined in Table 4-4 with and without ZHP connected. Individual frequencies start at 2200 Hz and sweep to 3400 Hz. Return loss measurements shall be made in accordance with IEEE 743. Figure 4-10 defines the test configuration that shall be used for return loss measurements on the remote end splitter. Table 4-4: POTS to line return loss requirements Splitter type Loop ZTR (Ω) ERL SRL-L SRL-H (dB) (dB) (dB) Comments POTS All Loops 600 >6 >5 >3 POTS All Loops 600 N/A N/A >2 Page 17 of 24 Single frequency POTS U-R U-C Remote End POTS Splitter POTS Test Equipment LINE ZTC Test Loop LPF DSL ZHP-r (Load) ZNL-r Return loss reference impedance NOTES ZNL-r is the impedance of the non-loaded loop model seen from the RT ZHP-r is the impedance presented to the POTS connection by a TU-R Figure 4-10: POTS to line return loss measurement 4.6.1.6 POTS to Line Intermodulation Distortion The intermodulation distortion contributed by the remote end splitter shall be measured using the test configuration of Figure 4-9 and the null loop. With an applied tone set per IEEE 743, at a level of -9 dBm, the second and third order intermodulation distortion products shall meet the requirements of Table 4-5. Table 4-5: POTS to line intermodulation distortion requirements Splitter Type Loop ZTC (Ω) ZTR (Ω) 2nd Order (dB) 3rd Order (dB) Frequency (kHz) POTS Null Loop 900 600 < -57 < -60 0.2 to 4.0 4.6.2 POTS to Line Longitudinal Balance The longitudinal balance of the POTS splitter can be measured using two different techniques. One technique is to treat the DSL splitter as a separate entity, which would require using a twoport test. The other technique is to treat the splitter, TU-C, and CO line card combination as a one-port network. One port tests are usually performed on network end splitters. 4.6.2.1 POTS to Line Longitudinal Balance – Two-Port Technique Two-port test method shall be used when testing the DSL splitter as a separate entity. The longitudinal balance of the DSL splitter (without loops), measured as a two-port device in either direction between the POTS and line port, shall be measured in accordance with IEEE Standard 455 [12]. The DSL port shall be shorted in the case where DC blocking capacitors are included as part of the splitter function. Otherwise, the DSL port shall be open. Because of the Page 18 of 24 maintenance signature, the applied longitudinal voltage shall be a maximum of 3.0 V peak to peak. A DC bias current of 25 mA shall be applied. The POTS to line longitudinal balance requirements are specified in Table 4-6. Table 4-6: POTS to line longitudinal balance requirements Splitter Type Loop ZTC (Ω) ZTR (Ω) Long. Balance Two-Port (dB) Frequency (kHz) POTS No Loop 900 600 > 58 0.2 to 1.0 POTS No Loop 900 600 > 58 – 53 linearly decreasing 3.2 to 4.0 The termination of the test set is for a series balance measurement per IEEE Standard 455 [12]. Prior to testing, a test circuit balance of 77 dB (58 + 19 dB) shall be achieved to insure 1 dB of accuracy. Figure 4-11 shows the test setup for the remote end DSL splitter with the DSL port open. If testing longitudinal balance on an integrated network modem, the TU-R shall be connected but powered down. DSL Port DSL LB Test Load LINE POTS LB Test Load Figure 4-11: POTS to line longitudinal balance measurement per IEEE 455 4.6.3 Transparent Testing Capacitance To minimize the effect of the splitter on the performance of metallic loop test systems, the input impedance is defined for a special narrow frequency band. 4.6.3.1 Tip to Ring Capacitance The intent of this requirement is to limit the maximum capacitance seen by metallic testing systems. By setting this limit, the metallic test systems can test POTS services with the accuracy and dependability of today. Overall the admittance of the POTS or PSTN port shall be capacitive. The capacitance present at either the POTS or PSTN interfaces in the frequency range of 20 to 30 Hz shall be a maximum of 300 nF. This amount includes the total capacitance due to the two splitters at the network end and the remote end with the attached modems. Page 19 of 24 The following, per end, maximum/minimums shall be met: Remote end splitter without modem connected: 115 nF Max 20 nF Min Modem input allowance: 35 nF Max 20 nF Min Multiplying the above numbers by two (for two modems and two POTS splitters) results in 300 nF maximum tip to ring capacitance. DSL Port DSL LINE POTS Capacitance Figure 4-12: Capacitance measurement 4.6.3.2 Capacitance to Ground There shall be no designed AC path to ground. The maximum stray capacitance from either tip or ring of the splitter to ground shall be less than 1.0 nF. 4.7 VDSL BAND TESTING The start and stop frequencies for testing in the DSL band are dependent on the technology (ADSL vs. VDSL). For VDSL splitters, the start and stop frequencies are dependent on the different profile options. The start frequency is denoted fmin will and the stop frequency is denoted fmax. Table 4-7: Profile frequency minimum and maximum Fmin [kHz] Fmax [MHz] Splitter Type ADSL 32 1.104 ADSL VDSL, 8a 25 8.5 VDSL2 VDSL, 8b 25 8.5 VDSL2 VDSL, 8c 25 8.5 VDSL2 Page 20 of 24 4.7.1 VDSL, 8d 25 8.5 VDSL2 VDSL, 12a 25 12 VDSL1, VDSL2 VDSL, 12b 138 12 VDSL1, VDSL2 VDSL, 17a 138 17.7 VDSL2 VDSL, 30a 138 30 VDSL2 DSL Band Attenuation The insertion loss of the low-pass filter and ZHP (i.e., the difference in insertion loss measured with and without the filter/ZHP combination), measured as shown in Figure 4-13, shall meet the requirements in Table 4-8. The insertion loss caused by the low pass filter in the DSL band shall be measured with an input level of 10 dBm. Table 4-8: DSL band attenuation requirements Splitter type Loop Line (Ω) ZTR (Ω) Insertion loss (dB) Frequency (kHz) POTS Null Loop 100 600 > 65 32 - 300 POTS Null Loop 100 600 > 55 300 - fmax DSL Port ZHP-r POTS LPF Line Port S I G Vm 600 Ohm Source 100 ohm fmin - fmax Balanced Page 21 of 24 Figure 4-13: DSL band attenuation measurement 4.7.2 DSL to Line Insertion Loss The Insertion loss caused by the splitter in the DSL band between nominal impedances as shown in Figure 4-14 shall meet the limits defined in Table 4-9. The insertion loss caused by the low pass filter in the VDSL band shall be measured with an input level of -10 dBm. Table 4-9: VDSL to line insertion loss requirements Splitter Type Loop Line (Ω) ZTR (Ω) Insertion loss (dB) Frequency (kHz) POTS Null Loop 100 600 0.5 fmin to fmax DSL Port Vm 100 Ohm POTS LPF Line Port S I G 600 Ohm Source 100 ohm fmin - fmax Balanced Figure 4-14: VDSL to line insertion loss measurement 4.7.3 VDSL Non-Linear Distortion The line and DSL ports of the splitter are terminated with 100 Ω and the POTS port is terminated in 600 Ω. Two tones with frequencies specified in Table 4-10, each with a power of 8.5 dBm, shall be injected into the DSL port and distortion shall be measured at the line port. The measured spurious levels shall meet the requirements that IM2 and IM3 are less than the power levels specified in the table. Table 4-10: Remote End VDSL2 splitter intermodulation test parameters VDSL2 Profile Frequency 1 (MHz) Frequency 2 (MHz) IM2 (dBc) IM3 (dBc) 8 0.12 3.8 ≤ TBD ≤ TBD Page 22 of 24 8 0.12 5.1 ≤ TBD ≤ TBD 8 3.8 5.1 ≤ TBD ≤ TBD 12 & 17 5.1 8.8 ≤ TBD ≤ TBD 30 11.8 24.0 ≤ TBD ≤ TBD Page 23 of 24 5. INFORMATIVE REFERENCES ANSI T1.401.01-2000, “Interface between Carriers and Customer Installations - Analog Switched Access Lines with the Line-Side Answer Supervision Feature.” ATIS Committee T1Technical Requirements Document “Technical Requirements- Maximum Voltage, Current, and Power Levels in Network Powered Devices.” U.S. Department of Agriculture, Rural Utilities Services, Bulletin 1753E-001 (Form 522), “RUS General Specification for Digital, Stored Program Controlled Central Office Equipment, RUS Form 522.” UL 60950; Underwriting Laboratories, “The Standard for Safety of Information Technology Equipment including Electrical Business Equipment.” UL 1863; Underwriting Laboratories, “Communications-Circuit Accessories”, Issue 4, May 14, 2004 UL 497A; Underwriting Laboratories, “Secondary Protectors for Communications Circuits”, Issue 3, March 20, 2001. Telcordia Technologies GR-1089-CORE Issue: 03 2000-06-30, – Electromagnetic Compatibility and Electrical Safety – Generic Criteria for Network Telecommunications Transmission Requirements and Objectives of the LATA Switching Systems Generic Requirements (LSSGR). Telcordia Technologies GR-506-CORE Issue: 01 1996-00-00, - LSSGR: Signaling for Analog Interfaces Page 24 of 24