Download Radio Frequency Immunity Requirements

Telecommunications Industry Association
TR41.7-09-11-007-L
Document Cover Sheet
Project Number
SP-3-3210-RV2 (to become TIA-631-B)
Document Title
Proposed Draft 1
Source
VTech Communications
Contact
Stephen R Whitesell
2 Shannon Ct
Howell, NJ 07731
Distribution
TR-41.7
Intended Purpose
of Document
(Select one)
X
Phone: 732 751 1079
Fax:
Email: [email protected]
For Incorporation Into TIA Publication
For Information
Other (describe) -
The document to which this cover statement is attached is submitted to a Formulating Group or
sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the
provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all
of which provisions are hereby incorporated by reference.
Abstract
In discussing the intent to open TIA-631-A for revision, one of the items pointed out was that the
document only covers test procedures for telephones with handsets, although this limitation is not
expressly stated in the scope of the document. This proposed Draft 1 for TIA-631-B includes an
informative annex suggesting how the send and receive RF immunity test procedures can be extended to
other products with an analog interface, such as speakerphones, answering systems and telephones
equipped with headsets.
v1.0 – 20050426
Telecommunications Industry Association
TR41.7-09-11-007-L
SP-3-3210RV2
To be ANSI/TIA-631-B
Telecommunications
Telephone Terminal Equipment
Radio Frequency Immunity Requirements
Formulated under the cognizance of TIA Subcommittee TR-41.7, Environmental and Safety
Considerations
With the approval of TIA Engineering Committee TR-41, User Premises Telecommunications
Equipment Requirements
@@@ Replace with new recognition format.
v1.0 – 20050426
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
TABLE OF CONTENTS
1.
SCOPE ____________________________________________________________________ 1
2.
CATEGORIES OF CRITERIA ________________________________________________ 2
3.
NORMATIVE REFERENCES _________________________________________________ 3
4.
ABBREVIATIONS, ACRONYMS, AND DEFINITIONS ___________________________ 4
5.
4.1.
ABBREVIATIONS AND ACRONYMS ..................................................................................... 4
4.2.
DEFINITIONS .......................................................................................................................... 5
TECHNICAL REQUIREMENTS ______________________________________________ 6
5.1.
GENERAL INFORMATION ...................................................................................................... 6
5.1.1.
Ambient Conditions ..................................................................................................... 6
5.1.2.
TTE Configuration and Operating Conditions............................................................. 7
5.1.3.
Test Configuration Conditions ..................................................................................... 7
5.1.4.
CO Simulator Analog DC Feed test circuit .................................................................. 8
5.1.5.
Standardized Telephone Load test circuit .................................................................... 9
5.2. IMMUNITY TO RADIATED ELECTRIC FIELD (E-FIELD) INTERFERENCE......................... 10
5.2.1.
Receive (Near end interference) Requirements ......................................................... 10
5.2.2.
Transmit (Far end interference) Requirements .......................................................... 11
5.2.3.
Functionality Requirements ....................................................................................... 11
5.2.4.
Method of Measurement ............................................................................................ 12
5.3. IMMUNITY TO CONDUCTED INTERFERENCE ON SIGNAL LEADS .................................. 16
5.3.1.
Receive (Near end interference) Requirements ......................................................... 16
5.3.2.
Transmit (Far end interference) Requirements .......................................................... 17
5.3.3.
Functionality Requirements ....................................................................................... 17
5.3.4.
Method of Measurement ............................................................................................ 18
5.4. IMMUNITY TO CONDUCTED INTERFERENCE ON POWER LEADS................................... 22
5.4.1.
Receive (Near end interference) Requirements ......................................................... 22
5.4.2.
Transmit (Far end interference) Requirements .......................................................... 23
5.4.3.
Functionality Requirements ....................................................................................... 23
5.4.4.
Method of Measurement ............................................................................................ 24
6. ALTERNATIVE METHOD CONDUCTED RF SIGNALS ON POWER AND SIGNAL
LEADS________________________________________________________________________ 26
ANNEX A - TEST EQUIPMENT (INFORMATIVE) _________________________________ 27
ANNEX B – OVERVIEW (INFORMATIVE) _______________________________________ 31
ANNEX C – HISTORICAL BACKGROUND (INFORMATIVE) _______________________ 32
ANNEX D – RFI CONSIDERATIONS (INFORMATIVE) _____________________________ 33
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Table of Figures
Figure 1 – CO simulator ........................................................................................................................ 8
Figure 2 – Standardize telephone test set simulator .............................................................................. 9
Figure 3 – Radiated mode near end requirement ................................................................................. 10
Figure 4 – Radiated mode far end requirement ................................................................................... 11
Figure 5 – General TEM cell test setups for radiated E-field immunity ............................................. 13
Figure 6 – Cordless TTE handset orientation for radiated E-field immunity ...................................... 14
Figure 7 – Cordless TTE angled handset orientation for radiated E-field immunity .......................... 14
Figure 8 – Corded handset orientation for radiated E-field immunity ................................................ 15
Figure 9 – Adjunct TTE orientation for radiated E-field immunity .................................................... 15
Figure 10 – Conducted mode on signal leads near end requirement ................................................... 16
Figure 11 – Conducted mode on signal leads far end requirement ..................................................... 17
Figure 12 – Test configuration for conducted immunity on signal leads ............................................ 20
Figure 13 – Cordless TTE handset orientation for conducted immunity ............................................ 20
Figure 14 – Corded TTE orientation for conducted immunity ............................................................ 21
Figure 15 – Adjunct TTE orientation for conducted immunity ........................................................... 21
Figure 16 – Conducted mode on power leads near end requirement................................................... 22
Figure 17 – Conducted mode on power leads far end requirement ..................................................... 23
Figure 18 – Detailed test configuration for metallic conducted immunity on power leads ................ 25
Figure 19 – TEM cell test configuration for conducted immunity ...................................................... 26
Figure 20 –Types of TEM cell............................................................................................................. 27
Table of Tables
Table 1 – Climatic conditions during testing......................................................................................... 6
Table 2 – RF signal characteristics for radiated mode E-field ............................................................ 10
Table 3 – RF signal characteristics for conducted mode on signal leads ............................................ 16
Table 4 – RF signal characteristics for conducted mode on power leads............................................ 22
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SP-3-3210-RV2
1. SCOPE
This standard specifies Radio Frequency (RF) immunity performance criteria for two-wire Telephone
Terminal Equipment (TTE) having an acoustic output and two-wire TTE adjunct devices with
connection port for Telephone Terminal Equipment (TTE) having an acoustic output. Acoustic
output requirements are only defined for TTE having a handset normally held to the ear of the user,
but guidance on extending the requirements to TTE having other types of acoustic outputs, such as
speakerphones, answering systems and telephones with headsets, is provided in an informative
annex.
Criteria are specified for immunity to radiated RF signals over the frequency range from 150 KHz to
150 MHz and for immunity to longitudinal (common mode) conducted RF signals over the frequency
range from 150 KHz to 30 MHz. Criteria for immunity to metallic (differential) conducted RF
signals on signal leads is not covered.
In addition to the performance levels themselves, this standard includes recommended test
procedures or references to existing standards wherein such procedures will be found.
This standard does not consider immunity performance criteria to intentional network signals
(e.g. xDSL).
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2. CATEGORIES OF CRITERIA
Three types of requirements are specified in this standard; Mandatory, Recommended and Permissive
1. Mandatory requirements are designated by the terms “shall” and “shall not”.
requirements are used to indicate conformity in which no deviation is permitted.
These
Recommended requirements are designated by the terms “should” and “should not”. These
requirements generally relate to compatibility or performance advantages towards which future
designs should strive.
Permissive requirements are designated by the terms “may” and “may not”. These requirements
are used to indicate an action that is permitted within the limits of the standard.
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3. NORMATIVE REFERENCES
The following standards contain provisions, which, through reference in this text, constitute
provisions of this Standard. At the time of publication, the editions indicated were valid. All
standards are subject to revision, and parties to agreements based on this Standard are encouraged to
investigate the possibility of applying the most recent editions of the standards indicated below.
ANSI and TIA maintain registers of currently valid national standards published by them.
@@@ This list of references needs to be updated.
1. ANSI C63.4-2001, American National Standard, Methods of Measurement of Radio-Noise
Emissions from Low-Voltage Electrical and Electronic Equipment in the Range of 9 KHz to 40
GHz.
2. CISPR 22-1997, Limits and Methods of Measurement of Radio Disturbance Characteristics of
Information Technology Equipment.
3. IEC 61000-4-3-2001, Electromagnetic Compatibility (EMC) - Part 4-3. Testing and
Measurement Techniques - Radiated, Radio-Frequency, Electromagnetic Field Immunity Test
4. IEC 61000-4-6-2001, Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement
Techniques - Section 6: Immunity To Conducted Disturbances, Induced By Radio-Frequency
Fields
5. IEC 61000-4-16, Electromagnetic Compatibility (EMC) - Part 4-16: Testing And Measurement
Techniques - Test For Immunity To Conducted, Common Mode Disturbances In The Frequency
Range 0 Hz To 150 KHz
6. IEC 60318-1-1998, Electroacoustics - Simulators of human head and ear - part 1: ear simulator
for the calibration of supra-aural earphones.
7. IEC 60318-2-1998, Electroacoustics - Simulators of human head and ear - part 2: an interim
acoustic coupler for the calibration of audiometric earphones in the extended high-frequency
range
8. IEC 60318-3-1998, Electroacoustics - Simulators of human head and ear - part 3: acoustic
coupler for the calibration of supra-aural earphones used in audiometry
9. TIA/EIA-810-A-2001, Telecommunications - Telephone Terminal Equipment - Transmission
Requirements For Digital Wireline Telephones
WARNING: This document contains references to the following work-in-progress which is subject
to change: PN-3-4350.110-RV3 (to be published as ANSI/TIA-470.110-C).
The most current version of PN-3-4350.110-RV3 is available in the public directory of TR-41.3.5 at:
http://ftp.tiaonline.org/tr-41/tr4135/Public/Latest-Revision-of-PN4350-110/
10. PN-3-4350.110-RV3 (to be published as ANSI/TIA-470.110-C) Telecommunications Telephone Terminal Equipment- Handset Acoustic Performance Requirements
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4. ABBREVIATIONS, ACRONYMS, AND DEFINITIONS
For the purpose of correct interpretation of this document, the following key technical terms and
abbreviations apply. Terms used in the document but not defined in this section shall be interpreted
according to their internationally accepted definition.
4.1.
ABBREVIATIONS AND ACRONYMS
For the purposes of this Standard, the following abbreviations and acronyms apply.
For the purpose of correct interpretation of this document, the following key abbreviations apply.
T&R
Tip and Ring terminals or interface
AM
Amplitude Modulation
ANSI
American National Standards Institute
AWG
American Wire Gauge
CISPR
International Special Committee on Radio Interference
CO
Central Office
E-field
Electric Field
EIA
Electronic Industries Association
EMC
Electro Magnetic Compatibility
FCC
Federal Communications Commission
GTEM
Gigahertz Transverse ElectroMagnetic
IEC
International Electrotechnical Commission
IEEE
Institute of Electrical and Electronics Engineers
LISN
Line Impedance Stabilization Network
RF
Radio Frequency
RFI
Radio Frequency Interference
TIA
Telecommunications Industry Association
TEM
Transverse Electro Magnetic
T-LISN
Telecommunications Line Impedance Stabilization Network
TTE
Telephone Terminal Equipment
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4.2.
SP-3-3210-RV2
DEFINITIONS
For the purposes of this Standard, the following definitions apply.
Off-Hook
Refers to the state of a particular CPE rather than the line state.
Auxiliary equipment
Equipment not under test, but indispensable for setting up all
functions and assessing the correct performance or operation of the
equipment under test during its exposure to RF signals.
Far end interference
Interference effects produced in the Telephone Terminal Equipment
(TTE) that manifest themselves in auxiliary equipment connected to
signal leads in the test configuration.
Ground plane
A conducting surface or plate used as the common reference point
for circuit or system.
RF Immunity
The ability of equipment to meet the performance criteria specified
in this standard in the presence of RF signals.
Line Impedance Stabilization Network (LISN) A network inserted between the leads of the TTE
and auxiliary equipment to provide a specified impedance through
which RF signals may be injected into the TTE and which prevents
RF signals from reaching the auxiliary equipment. Two types of
LISN are specified in this standard: the ANSI LISN for use on power
leads and the IEC T-LISN for use on signal leads.
Near end interference
Interference effects produced in the TTE that manifest themselves as
an acoustic output from the handset receiver.
Standardized Phone Load
A standardized telephone load circuit for replicating a telephone.
Radio Frequency Interference (RFI) Performance degradation, malfunction, or failure of
equipment due to the presence of RF signals.
Signal leads
Used to describe any conductors carrying signals between
equipment. This includes the tip and ring conductors of balanced
twisted pair cables.
Telephone Terminal Equipment (TTE) An electronic device which has a wireline connection to
the public telecommunications network.
hectoPascals
SI Measurement unit for measuring atmosphere pressure. 1013 hPa
equals 101.3 kiloPascals or 1013 millibars.
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5. TECHNICAL REQUIREMENTS
5.1.
GENERAL INFORMATION
Testing shall be performed at 100 logarithmically spaced points per decade. Dwell time shall be a
minimum of 0.5 seconds or the minimum response time, whichever is longer.
The alternative test methods may be used provided correlation to the preferred method can be shown.
5.1.1.
Ambient Conditions
In order to minimize the impact of environmental parameters on test results, the testing shall be
carried out under the ambient conditions described below:
5.1.1.1.
Climatic Conditions
The climatic conditions shall be within the ranges of Table 1:
Ambient temperature:
20°C to 25°C
Relative humidity (RH):
Atmospheric pressure:
(Normalized to Sea-Level Pressure)
20% to 70%
950 hPa to 1050 hPa
(hectoPascals)
Table 1 – Climatic conditions during testing
Note: hPa sea level = hPa observed + [(10 mb/100 m) * Elevation above sea level in meters].
5.1.1.2.
Measured Background Noise and Spectral Interference Conditions
The measured Background Noise and Spectral Interference levels (noise floor) shall not be greater
than 35 dBSPL for Near-end testing and -75 dBV for Far-end testing, determined per the following:
1. With all associated test equipment power on, remove the RF signal at the TEM Cell or LISN
inputs.
2. Perform the mock test run and measure the Background Noise and Spectral Interference levels.
Note: The TTE shall be off-hook during the Background Noise and Spectral Interference
measurement.
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5.1.2.
TTE Configuration and Operating Conditions
5.1.2.1.
TTE configuration
1. The TTE shall be configured for testing to simulate the real application as closely as possible.
Power and interconnecting cables shall be of the same types as supplied or recommended for use
with the equipment.
TTE with user adjustable configuration menus shall be changed from the power-up defaults and
memory location shall be filled for functional testing.
The TTE receive volume control shall be set to produce the reference Receive Loudness Rating
(RLR) specified in PN-3-4350.110-RV3 for analog TTE and TIA-810-A for digital TTE.
5.1.2.2.
TTE Signal and Power Cable Lengths
The cables supplied with the TTE shall be utilized for the radiated and conducted testing. The signal
and power cables shall be limited to  30cm in length by bundling and wrapping the excess cable.
See sections 5.2, 5.3 and 5.4 for the respective configuration details.
5.1.3.
Test Configuration Conditions
5.1.3.1.
Acoustic Coupling Tube
In order to avoid the effects of capacitive coupling to the metallic structure of an ear simulator or its
disturbing effects on the E-field, an acoustic coupling tube shall be used to measure the output of the
telephone receiver. The length of such an acoustic coupling tube shall be an integral number of
wavelengths of the demodulated 1000 Hz signal to be measured (e.g., N x 0.345 m for typical
laboratory conditions).
The tube shall be terminated and sealed at the handset with a non-conductive coupler having external
dimensions matching that of an ear simulator. The tube shall be made of a flexible, thick-walled,
non-conductive material. The inner diameter of the tube shall provide a snug fit around the
microphone and preamplifier assembly.
5.1.3.2.
Acoustic Coupling Tube Calibration
The acoustic coupling tube shall be calibrated using either of the following methods:
1. Using an acoustic calibrator device (e.g. Bruel & Kjaer 4231 Acoustic Calibrator), measure the
output voltage from the microphone terminating the acoustic coupling tube (measured by the
Selective Voltmeter in Figure 5) and reference the voltage level to the known acoustic calibrator
output level.
2. Apply a 1000 Hz, -20dBV signal to the TTE (as measured at T&R) and measure its acoustic
output on the ear simulator using the procedure for receive measurements described in PN-34350.110-RV3. Note the sound pressure level produced.
Using the identical test signal and other details of the test configuration (e.g., battery feed
circuitry) , measure the output voltage from the microphone terminating the acoustic coupling
tube. Adjust the indicating instrument to read the same sound pressure as previously measured .
Note: This calibration may be specific to the telephone being measured. Similar telephones
using the same handset style and type of receiver element will produce similar
calibrations. However, changing from one type of receiver element to another (e.g.,
from a moving coil to a piezo ceramic receiver) may give substantially different results
and requires a recalibration for the new receiver type.
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5.1.4.
CO Simulator Analog DC Feed test circuit
The CO Simulator shall be per Figure 1 below.
C2
L2
750 
Far-end
Electrical
Test Point
900 
Tip & Ring
Electrical
Point
R1
50V
L1
C1
Figure 1 – CO simulator
Notes:
1) The loss of the feed circuit should not be greater than 0.1dB over the range of 100 Hz to
8,000 Hz. Using the following ideal components the DC Feed circuit should meet this:
C  100 microfarads, L  5 Henries, Total Resistance = 400 Ohms, including the resistance
of L1 and L2 inductors + R1.
2) The TTE DC current shall be determined by the addition of the 750 ohm resistor between
the inductors, in series with the 400 ohm total feed circuit resistance for a total loop
resistance of 1150 ohms.
3) Resistor values shall be ± 1% and 1W.
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5.1.5.
Standardized Telephone Load test circuit
When testing TTE adjunct devices that have an electrical near-end output, the standardize telephone
test circuit below shall be used for measuring the electrical near-end output.
T (+)
R1
Electrical
Near-end
Electrical
Test Point
2
4
1
6
3
8
5
7
47 
600 
100 
R (–)
T1
Notes:
1) Circuit is polarity sensitive.
2) Use IN4004, or similar, for diode strings.
3) Resistor values shall be ± 1% and 1W.
4) T1 may be WECO 120C Repeat Coil or equivalent.
5) R1 + coil windings (Pin 2 to Pin 5) should be 53 .
Figure 2 – Standardize telephone test set simulator
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5.2.
(To be published as ANSI/TIA-631-B)
IMMUNITY TO RADIATED ELECTRIC FIELD (E-FIELD) INTERFERENCE
When subjected to the radiated E-field characterized in Table 2, the TTE, or adjunct TTE with an
attached TTE with an acoustic output shall meet the requirements of sections 5.2.1, 5.2.2, 5.2.3
below.
Frequency:
150 KHz to 150 MHz
E-Field Strength, unmodulated:
3 Vrms/m, +/- 0.5Vrms/m
Modulation:
1 KHz sinusoidal wave, 80% AM
Table 2 – RF signal characteristics for radiated mode E-field
Note: Cordless telephones are exempt from these requirements in their intended transmit
frequency band of operation and receive frequency band of operation.
5.2.1.
Receive (Near end interference) Requirements
1. The demodulated acoustic output from the handset receiver of the TTE shall not exceed 55
dBSPL, when measured at 1 KHz in all off-hook operating states that affect compliance.
2. In the frequency band from 500 KHz to 2 MHz the demodulated acoustic output should not
exceed 45 dBSPL (Conditional Region), when measured at 1 KHz in all off-hook operating states
that affect compliance.
3. For adjunct TTE, the demodulated electrical output from the adjunct “Phone” output shall not
exceed -55 dBV (1.77 mV).
Radiated - Near End - 150KHz to 150MHz
90
80
70
Unacceptable Region
dBSPL
60
Conditional
Region
50
40
Acceptable Region
30
20
10
0.1
1.0
10.0
100.0
Frequency (MHz)
Figure 3 – Radiated mode near end requirement
10
1000.0
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SP-3-3210-RV2
5.2.2.
Transmit (Far end interference) Requirements
1. The demodulated signal output measured on-hook and off-hook at the CO Simulator termination
shall not exceed -55 dBV (1.77 mV), when measured at 1 KHz for all operating states that affect
compliance.
2. In the frequency band from 500 KHz to 2 MHz the demodulated signal output should not exceed
-65 dBV (0.56 mV) (Conditional Region, when measured at 1 KHz for all operating states that
affect compliance.
Radiated - Far End - 150KHz to 150MHz
-20
-30
-40
Unacceptable Region
dBV
-50
Conditional
Region
-60
-70
Acceptable Region
-80
-90
-100
0.1
1.0
10.0
100.0
1000.0
Frequency (MHz)
Figure 4 – Radiated mode far end requirement
5.2.3.
Functionality Requirements
The TTE shall be tested for functionality per the following:
1. During radiated testing, the TTE shall not change operating state.
After radiated testing and without power resetting and recycling the TTE operating state, the TTE
shall maintain basic functionality of transmit, receive, address signaling, and alerting.
After radiated testing and without power resetting and recycling the TTE operating state, the TTE
shall maintain the configuration and call memory.
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5.2.4.
Method of Measurement
To test the radiated E-field immunity of an TTE, the basic configuration is shown in Figure 5, Figure
6, Figure 7 or Figure 8.
1. A predetermined E-field strength can be established in the TEM cell by controlling the output
voltage measured at the TEM cell termination (e.g. lockup table).
Note: The E-field (V/m) generated is the voltage between septum and the ground, divided by
the septum-to-ground spacing expressed in meters.
An E-field probe and field strength meter may be used as an alternative method for establishing the
E-field in the TEM cell. The E-field probe should be located in the top half of the TEM cell,
midway between the septum and the top of the cell. The probe and field strength meter allow the
magnitude of the E-field to be read directly in V/m.
An acoustic tube shall be used to couple the output sound pressure signal out of the TEM cell to a
microphone.
The TTE shall be tested in 3 orthogonal orientations. The X orientation shall be with the rear of the
TTE faces the Handset position, the Y orientation is with the TTE is rotated 90 degrees to the
right from the X orientation and the Z orientation is with the TTE in a wall mount position if
supported by the TTE. The Telephone base unit shall be placed 10 cm above the bottom of the
TEM cell on a non-metallic support. The signal leads shall be no longer than 30 cm with
minimum exposure to the E-field.
The handset on corded telephones shall be supported in such a manner as to allow the handset cord to
rise 20 cm above the 10 cm reference plane (i.e., 30 cm above the bottom of the TEM cell). The
separation between the handset and the base unit shall be 30 cm. All excess cord length shall be
arranged in a serpentine, non-inductive manner 10 cm above the bottom of the TEM cell. See
Figure 8.
The antenna on cordless base units shall be oriented vertically and extended such that the end of the
antenna is 20 cm above the 10 cm reference plane (i.e., 30 cm above the bottom of the TEM cell)
or to its maximum height, whichever is greater. The cordless handset shall be placed 30 cm
away from the base unit. If necessary The cordless handset canted towards the base with the tip
of the antenna 30 cm from the base. The antenna shall be extended maximally or to make a total
length (handset and antenna) of 30 cm, whichever is less.
If a GTEM cell is used instead of a TEM cell, the E-field strength shall be determined by measuring
the input voltage applied to the septum and dividing by the septum to cell bottom spacing
determined at the location of the TTE. The alternative method of using an E-field probe in the
top half of the cell to measure the field strength cannot be used directly in a GTEM cell because
the field strength in the top half of the cell is not the same as in the bottom half due to the offcenter location of the septum. Depending on the size of the GTEM cell, the reference plane on
which the TTE is placed may need to be elevated more than 10 cm above the cell bottom to keep
the TTE in the middle 1/3 of the septum to cell bottom spacing. All other dimensions relative to
the placement of the handset, draping of the handset cord, etc. shall be the same as specified for
measurements in a TEM cell.
5.2.4.1.
General Precautions
Precautions should be taken to eliminate unwanted interference generated by the spurious response
of the signal sources (e.g., harmonics being detected by the receiver of cordless telephones).
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SP-3-3210-RV2
RF V/m
meter
50
ohms
Acoustic coupling tube
TLISN
RF
Voltmeter
10cm
Mic &
Preamp
RF
Amplifier
CO
Simulator
Selective
Voltmeter
RF
Generator
Selective
Voltmeter
Controller/
Recorder
Alternative
Methods
Figure 5 – General TEM cell test setups for radiated E-field immunity
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(To be published as ANSI/TIA-631-B)
< 20cm
Base
Antenna
Acoustic coupling tube
Handset
30 cm
Base Unit
Non-metallic TTE support
Signal and Power
Cables < 30 cm
10 cm
Test Chamber wall
(Not to Scale or complete)
Figure 6 – Cordless TTE handset orientation for radiated E-field immunity
Note: If the Handset antenna height is greater than 20 cm from the TTE support then the
handset shall be angled with the tip of the antenna remaining at 30 cm separation from
the base and end of the handset on the TTE support moving toward the base unit.
30 cm
< 20cm
Base
Antenna
Handset
Acoustic Tube
Base Unit
Signal and Power
Cables < 30 cm
Non-metallic TTE support
10 cm
Test Chamber wall
(Not to Scale or complete)
Figure 7 – Cordless TTE angled handset orientation for radiated E-field immunity
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Handset supported with a
non-metallic fixture
30 cm
20cm
Base
Unit
Acoustic coupling tube
Non-metallic TTE support
Signal and/or Power
Cables < 30 cm
10 cm
Test Chamber wall
(Not to Scale or complete)
Figure 8 – Corded handset orientation for radiated E-field immunity
Adjunct
TTE
Non-metallic TTE support
Signal and/or Power
Cables < 30 cm with minimum
exposure to the E-field
10 cm
Test Chamber wall
Adjunct "phone" line
connection
Isolation
T-LISN
Standardized
Phone Load
Selective
Voltmeter
(Not to Scale or complete)
Figure 9 – Adjunct TTE orientation for radiated E-field immunity
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SP-3-3210-RV2
5.3.
(To be published as ANSI/TIA-631-B)
IMMUNITY TO CONDUCTED INTERFERENCE ON SIGNAL LEADS
When the Signal leads are subjected to the conducted RF signal characterized in Table 3, the TTE, or
adjunct TTE with an attached TTE with an acoustic output, shall meet the requirements of sections
5.3.1, 5.3.2, 5.3.3 below.
Frequency:
150 KHz to 30 MHz
Signal Strength, unmodulated:
3 Vrms, +/-0.25 Vrms
Modulation:
1 KHz sinusoidal wave, 80% AM
Table 3 – RF signal characteristics for conducted mode on signal leads
5.3.1.
Receive (Near end interference) Requirements
1. The demodulated acoustic output from the handset receiver of the TTE shall not exceed 55
dBSPL, when measured at 1 KHz in all off-hook operating states that affect compliance.
2. In the frequency band from 500 KHz to 2 MHz the demodulated acoustic output should not
exceed 45 dBSPL(Conditional Region), when measured at 1 KHz in all off-hook operating states
that affect compliance.
For adjunct TTE, the demodulated electrical output from the adjunct “Phone” output shall not exceed
-55 dBV (1.77 mV).
Conducted Signal Leads - Near End - 150KHz to 30MHz
90
80
70
Unacceptable Region
dBSPL
60
Conditional
Region
50
40
Acceptable Region
30
20
10
0.1
1.0
10.0
Frequency (MHz)
Figure 10 – Conducted mode on signal leads near end requirement
16
100.0
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
5.3.2.
Transmit (Far end interference) Requirements
1. The demodulated signal output measured on-hook and off-hook at the CO Simulator termination
shall not exceed -55 dBV (1.77 mV), when measured at 1 KHz for all operating states that affect
compliance.
2. In the frequency band from 500 KHz to 2 MHz the demodulated signal output should not exceed
-65 dBV (0.56 mV) (Conditional Region), when measured at 1 KHz for all operating states that
affect compliance.
Conducted Signal Leads - Far End - 150KHz to 30MHz
-20
-30
-40
Unacceptable Region
dBV
-50
Conditional
Region
-60
-70
Acceptable Region
-80
-90
-100
0.1
1.0
10.0
100.0
Frequency (MHz)
Figure 11 – Conducted mode on signal leads far end requirement
5.3.3.
Functionality Requirements
The TTE shall be tested for functionality per the following:
1. During conducted testing, the TTE shall not change operating state.
After Conducted testing and without power resetting and recycling the TTE operating state, the TTE
shall maintain basic functionality of transmit, receive, address signaling, and alerting.
After conducted testing and without power resetting and recycling the TTE operating state, the TTE
shall maintain the configuration and call memory.
17
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
5.3.4.
Method of Measurement
This test method is designed to simulate the radiated signals introduced on the Premises wiring that
appear as conducted RF signals to the TTE.
1. Longitudinal (common) mode interference shall be applied individually to balanced
telecommunications tip and ring leads of the TTE.
Combined signal and power leads, using ordinary telephone pairs, are to be treated as signal leads.
The test configuration shall provide a means of feeding power without adversely affecting the
signal.
5.3.4.1.
Test Procedures
1. The test configuration shall be as shown in Figure 12. This figure is the conducted RF signal
injection test configuration for the general case, involving signal leads. Cordless TTE shall be
configured as shown in Figure 13, Corded TTE shall be configured as shown in Figure 14,
Adjunct TTE shall be configured as shown in Figure 15.
Alternative test equipment may be used in which the open circuit voltage, source impedance, and
short-circuit current characteristics of the voltage injection generator can be shown to conform to
the requirement of immunity to conducted interference on signal leads (refer to section 5.3).
Measurement shall be performed on a non metallic support 10 cm over a metallic ground plane such
as copper or brass solid plate, with the following dimensions:

Minimum surface area of 2.25 m2.

Minimum length of 0.9 m on the shorter side.
2. When testing is performed in a shielded enclosure, the ground plane shall be bonded to the
shielded enclosure so that direct current bonding resistance does not exceed 2.5 mΩ. The
distance between adjacent bonds shall not exceed 90 cm.
3. When testing is performed outside of a shielded enclosure, the ground plane shall be grounded to
the safety ground of the mains supply, which powers the test equipment used in the tests. A
number 6 AWG copper conductor should be utilized. Connection practice shall comply with
local electrical utility safety regulations. The distance between the TTE and any vertical metallic
surface shall not be less than 40 cm.
4. The base unit shall be configured and oriented as it is intended to be installed, with the rear of
the TTE facing away from the Handset. The handset, handset cord, test leads and TTE leads shall
be kept 10 cm above the ground plane. Any excess handset cord length shall be arranged in a
serpentine, non-inductive manner.
5. The RF signal levels to be used during this test are specified in section 5.3. The levels given
apply to the unmodulated RF carrier at each test frequency (see section 5.1). Once the desired
level of the carrier signal is established at a given frequency, it shall be 80% amplitude
modulated with a 1 KHz sine wave while checking the TTE for immunity. The process of
conducting a frequency sweep of the modulated signal while maintaining the desired level of the
unmodulated carrier shall be achieved in one of the following ways:

With the modulation turned off, adjust the RF signal source to produce the desired signal
level as measured by the RF voltmeter at the input of the appropriate LISN. Turn on the
80% AM, 1 KHz modulation and monitor the TTE for compliance with the criteria
specified in section 5.3. Then turn the modulation off, change to the next frequency, and
repeat the process.
18
(To be published as ANSI/TIA-631-B)

SP-3-3210-RV2
With the modulation turned off, adjust the RF signal source to produce the desired signal
level as measured by the RF voltmeter at the input of the appropriate LISN. Turn on the
80% AM, 1 KHz modulation and observe the new reading of the RF voltmeter. It should
be approximately 1.15 times the previous reading, or 1.2 dB higher (see notes 1 & 2).
Sweep through the desired frequency range while maintaining this higher RF voltmeter
reading and monitoring the TTE for compliance with the criteria specified in section 5.3
Note 1: This difference in readings applies for a true RMS RF voltmeter.
Note 2: Checks should be made at various frequencies to ensure that the difference in RF
voltmeter readings for the modulated and un-modulated signals remains constant over
the specified frequency range.
The point of measurement of the injected voltage shall be at the output of the 6 dB attenuator as
shown in Figure 12. All leads shall be elevated, as much as possible, above the ground plane at a
constant height of 10 cm to render transmission line effects more repeatable.
The maximum length of the RF voltage sensing leads is 30 cm. This length is measured from the
TTE to the high impedance probe used.
5.3.4.2.
General precautions
Exercise caution when performing conducted immunity testing on signal leads in order not to damage
high-impedance voltage probes.
19
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
< 30 cm
50 on
Input
Power
Leads
LISN
Acoustic coupling tube
TLISN
10cm
10cm
RF
Voltmeter
Non Conductive Plane
Mic &
Preamp
Ground Plane
6dB
Pad
CO
Simulator
RF
Amplifier
Selective
Voltmeter
Selective
Voltmeter
RF
Generator
Controller/
Recorder
(Not to scale or complete)
NOTE: T-LISN utilized shall be designed to handle the injected RF Power level.
Figure 12 – Test configuration for conducted immunity on signal leads
Base
Antenna
Handset
Signal and Power
Cables < 30 cm
Acoustic coupling tube
30 cm
Base Unit
Non-metallic TTE support
10 cm
Ground Plane
(Not to Scale or complete)
Figure 13 – Cordless TTE handset orientation for conducted immunity
20
(To be published as ANSI/TIA-631-B)
Base
Unit
SP-3-3210-RV2
30 cm
Signal and/or
Power Cables
< 30 cm
Acoustic coupling tube
Non-metallic TTE support
10 cm
Ground Plane
(Not to scale or complete)
Figure 14 – Corded TTE orientation for conducted immunity
Signal and/or Power
Cables < 30 cm & on the
non-metallic support
Adjunct
TTE
Non-metallic TTE support
10 cm
Ground Plane
Adjunct "phone" line
connection
Parallel
Phone
Load
Isolation
T-LISN
Selective
Voltmeter
(Not to scale or complete)
Figure 15 – Adjunct TTE orientation for conducted immunity
21
SP-3-3210-RV2
5.4.
(To be published as ANSI/TIA-631-B)
IMMUNITY TO CONDUCTED INTERFERENCE ON POWER LEADS
When the Neutral and Hot Power Leads are each subjected to the RF signal characterized in Table 4,
the TTE, or adjunct TTE with an attached TTE with an acoustic output shall meet the requirements
of sections 5.4.1, 5.4.2, 5.4.3.
Frequency:
150 KHz to 30 MHz
Signal Strength, unmodulated:
3 Vrms, +/-0.25 Vrms
Modulation:
1 KHz sinusoidal wave, 80% AM
Table 4 – RF signal characteristics for conducted mode on power leads
5.4.1.
Receive (Near end interference) Requirements
6. The demodulated acoustic output from the handset receiver of the TTE shall not exceed 55
dBSPL, when measured at 1 KHz in all off-hook operating states that affect compliance.
7. In the frequency band from 500 KHz to 2 MHz the demodulated acoustic output should not
exceed 45 dBSPL(Conditional Region), when measured at 1 KHz in all off-hook operating states
that affect compliance.
For adjunct TTE, the demodulated electrical output from the adjunct “Phone” output shall not exceed
-55 dBV (1.77 mV).
Conducted Power Leads - Near End - 150KHz to 30MHz
90
80
70
Unacceptable Region
dBSPL
60
Conditional
Region
50
40
Acceptable Region
30
20
10
0.1
1.0
10.0
Frequency (MHz)
Figure 16 – Conducted mode on power leads near end requirement
22
100.0
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
5.4.2.
Transmit (Far end interference) Requirements
1. The demodulated signal output measured on-hook and off-hook at the CO Simulator termination
shall not exceed -55 dBV (1.77 mV), when measured at 1 KHz for all operating states that affect
compliance.
2. In the frequency band from 500 KHz to 2 MHz where the demodulated signal output should not
exceed -65 dBV (0.56 mV) (Conditional Region), when measured at 1 KHz for all operating
states that affect compliance.
Conducted Power Leads - Far End - 150KHz to 30MHz
-20
-30
-40
Unacceptable Region
dBV
-50
Conditional
Region
-60
-70
Acceptable Region
-80
-90
-100
0.1
1.0
10.0
100.0
Frequency (MHz)
Figure 17 – Conducted mode on power leads far end requirement
5.4.3.
Functionality Requirements
The TTE shall be tested for functionality per the following:
1. During radiated testing, the TTE shall not change operating state.
After radiated testing and without power resetting and recycling the TTE operating state, the TTE
shall maintain basic functionality of transmit, receive, address signaling, and alerting.
After radiated testing and without power resetting and recycling the TTE operating state, the TTE
shall maintain the configuration and call memory.
23
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
5.4.4.
Method of Measurement
The test method is designed for those power leads of a TTE which in practice are of much greater
length than the shorter runs that may be illuminated in the radiated test. In addition, the test method
is also intended to simulate potential differences that may exist between grounding nodes of a system
installation. The test level is applicable to both the longitudinal and the metallic modes of
interference injection as follows:
1. Power leads Metallic mode interference shall be applied to all ungrounded power conductors of
the system one conductor at a time.
Combined signal and power leads which combine both signal and power, such as ordinary telephone
pairs, are to be treated as signal leads. The test configuration shall provide a means of feeding
power without adversely affecting the signal.
The test level within the 150 KHz to 30 MHz band shall be in accordance with the requirements
given in sub clause 5.4. Each of the above modes shall be tested independently.
5.4.4.1.
Test Procedures
1. The test configuration shall be as shown in Figure 18. This figure is the conducted RF signal
injection test setups for the general case, involving power leads. Cordless TTE shall be
configuration as shown in Figure 13, Corded TTE shall be configuration as shown in Figure 14,
Adjunct TTE shall be configuration as shown in Figure 15.
Alternative test equipment may be used in which the open circuit voltage, source impedance, and
short-circuit current characteristics of the voltage injection generator can be shown to conform to
the requirement of immunity to conducted interference on signal leads (refer to section 5.4).
Measurement shall be performed on a non metallic support 10 cm over a metallic ground plane such
as copper or brass solid plate, with the following dimensions:

Minimum surface area of 2.25 m2.

Minimum length of 0.9 m on the shorter side.
2. When testing is performed in a shielded enclosure, the ground plane shall be bonded to the
shielded enclosure so that direct current bonding resistance does not exceed 2.5 mΩ. The
distance between adjacent bonds shall not exceed 90 cm.
3. When testing is performed outside of a shielded enclosure, the ground plane shall be grounded to
the safety ground of the mains supply, which powers the test equipment used in the tests. A
number 6 AWG copper conductor is suggested. Connection practice shall comply with local
electrical utility safety regulations. The distance between the TTE and any vertical metallic
surface shall not be less than 40 cm.
4. The base unit shall be configured and oriented as it is intended to be installed, with the rear of
the TTE facing away from the Handset. The handset, handset cord, test leads and TTE leads shall
be kept 10 cm above the ground plane. Any excess handset cord length shall be arranged in a
serpentine, non-inductive manner.
5. The RF signal levels to be used during this test are specified in section 5.4. The levels given
apply to the unmodulated RF carrier at each test frequency (see section 5.1). Once the desired
level of the carrier signal is established at a given frequency, it shall be 80% amplitude
modulated with a 1 KHz sine wave while checking the TTE for immunity. The process of
conducting a frequency sweep of the modulated signal while maintaining the desired level of the
unmodulated carrier shall be achieved in one of the following ways:
24
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2

With the modulation turned off, adjust the RF signal source to produce the desired signal
level as measured by the RF voltmeter at the input of the appropriate LISN. Turn on the
80% AM, 1 KHz modulation and monitor the TTE for compliance with the criteria
specified in section 5.3. Then turn the modulation off, change to the next frequency, and
repeat the process.

With the modulation turned off, adjust the RF signal source to produce the desired signal
level as measured by the RF voltmeter at the input of the appropriate LISN. Turn on the
80% AM, 1 KHz modulation and observe the new reading of the RF voltmeter. It should
be approximately 1.15 times the previous reading, or 1.2 dB higher (see notes 1 & 2).
Sweep through the desired frequency range while maintaining this higher RF voltmeter
reading and monitoring the TTE for compliance with the criteria specified in section 5.3
Note 1: This difference in readings applies for a true RMS RF voltmeter.
Note 2: Checks should be made at various frequencies to ensure that the difference in RF
voltmeter readings for the modulated and unmodulated signals remains constant over
the specified frequency range.
The point of measurement of the injected voltage shall be at the output of the 6 dB attenuator as
shown in Figure 13. All leads shall be elevated, as much as possible, above the ground plane at a
constant height of 10 cm to render transmission line effects more repeatable.
The maximum length of the RF voltage sensing leads is 30 cm. This length is measured from the
TTE to the high impedance probe used.
Acoustic coupling tube
<30cm
Power
Leads
LISN
T-LISN
50 on
input
Non Conductive Plane
10cm
Ground Plane
10cm
6dB
Pad
RF
Voltmeter
CO
Simulator
RF
Amplifier
Mic &
Preamp
Selective
Voltmeter
Selective
Voltmeter
RF
Generator
Controller/
Recorder
Figure 18 – Detailed test configuration for metallic conducted immunity on power leads
5.4.4.2.
General precautions
Exercise caution when performing conducted immunity testing on power leads in order not to
damage high-impedance voltage probes.
25
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
6. ALTERNATIVE METHOD CONDUCTED RF SIGNALS ON POWER AND SIGNAL
LEADS
To test the conducted immunity of an TTE, the basic configuration for telephone terminal equipment
with handsets is shown in Figure 12, Figure 14, Figure 18, and Figure 19.
The signal generator shall be 80% amplitude modulated with a 1kHz sine wave. By adjusting the
power level of the amplitude modulated generator, a predetermined interference signal can be
injected into the cables of the TTE. Detailed test procedures are similar to those given in section
5.3.4
The telephone base unit and handset shall be centrally located between the sides, 10 cm above the
bottom of the TEM cell (which serves as the ground plane), and separated from each other by 30 cm.
All excess cord length shall be arranged in a serpentine, non-inductive manner 10 cm above the
bottom of the TEM cell.
The response may be monitored by an ear simulator which is connected to a multimeter through a
preamplifier and a filter.
Alternatively, an acoustic tube can be used to couple the output sound pressure signal out of the
TEM cell to a microphone. Then through a similar network as is used for the ear simulator, the
sound pressure produced in the telephone handset, due to audio rectification of the conducted
interference, can be measured.
50 ohms
50 ohms
Artificial ear
EUT
0.3 m maximum
Preamplifier
10cm
Acoustic Tube
Microphone
T-LISN
Artificial C.O.
Alternate
Test Methods
0.1 m maximum
Signal generator
and
power amplifier
V
6 dB pad
Selective
Voltmeter
Figure 19 – TEM cell test configuration for conducted immunity
26
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
ANNEX A - TEST EQUIPMENT (INFORMATIVE)
TEM and GTEM Cells (informative annex?)
The useful frequency range of a TEM cell depends on its physical shape and dimensions. For a
symmetrical TEM cell (Figure 20a), an important parameter is the distance d between the septum and
the bottom internal wall of the cell. For a TEM cell with d equal to 0.592 m, the operating frequency
range is from DC to 150 MHz. A larger TEM cell will have a lower high frequency limit and will
not cover the frequency range required by section 5.2. Smaller TEM cells with higher cut-off
frequencies are not practical for large TTE, since the TTE should be confined to the middle 1/3 of
the distance between the septum and the bottom of the cell for maximum uniformity of the E-field.
For a tapered GTEM cell (Figure 20b), the upper frequency limit is not dependent on d and extends
to several GHz. The restriction that the TTE be confined to the middle 1/3 of the septum to cell
bottom distance for maximum uniformity of the E-field still applies, but does not limit the size of the
TTE that can be tested provided a large enough GTEM cell is available.
Figure 20 –Types of TEM cell
27
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
Test equipment Lists
The follow is a list of test equipment that may be used for RFI testing.
Radiated Mode List of Equipment

TEM or GTEM cell

Ear simulator or Acoustic Tube

T-LISN and LISN

Signal Generator with amplitude modulation capability and power amplifier

Preamplifier

Selective Voltmeter

Multi-meter

RF voltmeter and probe

E-field probe
Conducted Signal Leads Mode List of Equipment

Ground Plane

Ear simulator or acoustic tube

T-LISN and LISN

Signal generator with amplitude modulation capability and power amplifier

Preamplifier

Selective voltmeter

DC Feed circuitry

RF Voltmeter and Probe
Conducted Power Leads Mode List of Equipment

Ground Plane

Ear simulator or acoustic tube

T-LISN and LISN

Signal generator with amplitude modulation capability and power amplifier

Preamplifier

Selective voltmeter

DC Feed circuitry

RF Voltmeter and Probe
28
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
Line Impedance Stabilization Network
A Line Impedance Stabilization Network (LISN) is needed for conducted immunity measurements.
In general, the LISN housing and the ground plane shall be electrically bonded together in such a
manner that they are kept at the same RF potential.
ANSI LISN
A LISN applicable for the frequency band from 150 KHz to 30 MHz, is to be used with the power
leads of the equipment under test, see ANSI C63.4 for more information on the ANSI LISN.
T-LISN
A T-LISN applicable for the frequency band from 150 KHz to 30 MHz, is to be used with the signal
leads of the TTE.
The electrical characteristics of the T-LISN are as follows:
1. Common mode impedance:

150 ±20 Ω

Phase angle ±20°
Isolation between the TTE port and the auxiliary equipment port shall be:

At least 25 dB.
Insertion loss is defined in relation to the differential mode impedance as follows:

Less than 1.0 dB for 100 Ω

Less than 1.5 dB for 150 Ω

Less than 2.0 dB for 600 Ω
RF Signal Generating Equipment
Any commercially available signal source, power amplifiers, power oscillators, and general purpose
amplifiers capable of developing the required RF signal test levels, may be used, provided the
following requirements are met:

Frequency accuracy shall be within ±2%.

Harmonics and spurious output (that is, harmonic contents) shall not exceed a level of 30
dB below the power of the fundamental.
The power amplifier should be able to provide a power level of the order of 10 W or more for a
typical immunity threshold level. The injection process depends on the efficiency of the T-LISN and
the attenuator used to stabilize the operation of the power amplifier.
The RF signal generating equipment should have a 50 Ω output impedance and be capable of
delivering the required interference voltage within the frequency band 150 KHz to 150 MHz. The
RF signal shall be a carrier 80% amplitude modulated with a 1 KHz sine wave.
Selective voltmeter
A selective voltmeter may be used for the immunity tests of telephone sets. It shall have adequate
sensitivity for the frequency band of interest.
29
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
Voltage probe
The voltage probe’s input impedance shall be greater than or equal to 1 MΩ shunted by a capacitor
of 3 pF.
RF Voltmeter
A RF voltmeter and associated probe having a combined minimum sensitivity of 0.1 V and a
minimum input impedance of 5 kΩ over the frequency range from 150 KHz to 150 MHz is necessary
for measuring the RF signal level injected into the LISN for conducted immunity measurements and
the signal level provided to the TEM or GTEM cell for radiated immunity measurements.
E-field probe
An E-field probe and associated metering unit having a minimum sensitivity of 0.3 V/m over the
frequency range from 150 KHz to 150 MHz may be used for measuring the field strength in a TEM
or GTEM cell.
30
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
ANNEX B – OVERVIEW (INFORMATIVE)
This standard is one of a series of technical standards on telecommunications terminal equipment
prepared by TIA Engineering Committee TR-41. It will be useful to anyone engaged in the
manufacturing of telecommunications terminal equipment and to those purchasing, operating, or
using such equipment or devices.
Many electronic consumer products in the marketplace employ circuitry that generates radio
frequency (RF) energy, even though the given product is not intended to radiate a signal outside its
plastic or metal enclosure. Radio receivers (AM and FM), stereo music players, TV sets and
telephone sets are examples of such products. At the same time, some of these products
unintentionally demodulate radio signals from other devices or radio/TV transmitters and cause user
annoyance due to the interfering signals that can often be heard in telephone handset receivers, audio
amplifiers or seen on the TV screen.
The major increase in the number of interference complaints in the early 1990’s caused the FCC to
seek industry assistance in developing programs to minimize product susceptibility to extraneous
radio signals. The purpose of this standard is to provide requirements for the immunity of telephone
terminal equipment to RF signals. Compliance with these requirements will permit a product to
function normally in the majority of locations where it is used.
It is important to note that the mitigation of RF susceptibility problems in products is much easier to
accomplish in the product design stage rather than after it is sold and in the user’s hands. In fact,
some products cannot be successfully modified in the field to mitigate interference problems.
The RF environment described in this document pertains to all telecommunications terminals. In
addition to specifying RF immunity levels for equipment covered under the scope, this standard
provides information on test apparatus, testing system arrangement and measurement techniques.
Future Considerations
As technology and application engineering techniques advance, the criteria contained in this
document will become subject to change.
31
SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
ANNEX C – HISTORICAL BACKGROUND (INFORMATIVE)
During 1991 and 1992, a continuing high level of consumer complaints of Radio Frequency
Interference (RFI) trouble in telecommunications terminal equipment prompted the Federal
Communications Commission (FCC) to seek industry support for problem mitigation. Under the
auspices of the FCC’s Los Angeles Regional Field Office, a series of open meetings was convened to
address opportunities for public education, product design improvement and related issues. During
these meetings, the FCC sought the participation of the Telecommunications Industry Association
(TIA), among other groups, and approval was obtained for the TR-41 User Premises Telephone
Equipment Requirements Committee to initiate various projects in support of the FCC program.
It was determined that the RFI mitigation effort could be best accommodated in the TR-41.7
Environmental and Safety Considerations Subcommittee; thus, working group TR-41.7.3 on
Electromagnetic Compatibility (EMC) Considerations was established. In the administration of its
work on the various projects, the working group received supporting comments from the following
sources:
1. The FCC
Radio and TV Station Engineers
Telecommunications Companies
Communications Industry consultants
IEEE Standards Committee C63
American Radio Relay League
Consumers
Telecommunications Equipment Manufacturers
Industry Trade Associations
The initial task of the subcommittee was the preparation of a single page, double-sided procedural
document to assist the consumer in analyzing an apparent instance of RFI in a telecommunications
terminal. Simple, step-by-step test recommendations were included together with recommendations
on the use of RFI filters.
With the completion of the procedural document, the subcommittee laid plans for the origination of a
standard for RFI immunity levels and test methods. In as much as considerable information was
available within the public domain on the topic of RF immunity, the committee elected to avail itself
of various existing documents for its purposes. This approach permitted the project to be completed
within a much shorter time interval than would have otherwise been the case. The document below
was the primary reference standard.
Technical Advisory Document (TAD) 8465, “Electromagnetic Compatibility Requirements and Test
Methods for Telecommunications Equipment and Systems”, Issue 1, April 1992, Bell Canada .
At the time of the development of this standard, information regarding metallic (differential) RF
signals was limited. As this information becomes available, it is anticipated that it will be
incorporated in this standard to fully characterize the RF immunity of Telephone Terminal
Equipment (TTE).
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(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
ANNEX D – RFI CONSIDERATIONS (INFORMATIVE)
Considerations
Equipment complying with this standard is expected to provide reasonable immunity to RF
interference at an acceptable cost to the consumer. However, a few percent of the population may
continue to experience RF interference when using compliant equipment. The requirements represent
a balance of the factors involved in achieving RF immunity such as:
1. Two test methods were possible - using typical RF signals and a low noise criterion, or using
strong RF signals and a high noise criterion. Since measuring low noise levels is very difficult,
the latter method is used. The methods are not strictly equivalent because noise levels are not
linear with RF signal strength, but the method chosen is expected to be the more severe.
A 55 dBSPL noise level would be objectionable to most people, but this noise would only occur with
exceptional RF signals. If the noise is intermittent, such as might occur with citizens band (CB)
radio, the noise could be tolerable. If the noise is constant or involves intelligible speech,
additional RF filtering may be necessary.
Functionality with the exceptional RF signals is important because the product should be usable in
the event of an emergency.
The electromagnetic environment contains a broad range of frequencies, but only those frequencies
likely to cause interference in TTE are used.
The electromagnetic environment does not have a uniform field strength with frequency, being
strongest in the AM radio band. However, equipment is tested with a constant strength RF signal
to harmonize with international test methods. Instead of testing equipment with a variable signal
strength and a constant noise criterion, equipment is tested with a constant signal strength and a
variable noise criterion.
RF signals from 150 KHz to 30 MHz are picked up primarily on building wiring and conducted into
the equipment. The conducted immunity requirements are more severe than the radiated
requirements over the same frequency range, but the radiated tests are maintained because they
are not a burden to perform. RF signals from 30 to 150 MHz are picked up primarily by the
handset cord and wiring within the equipment, so there is no conducted equivalence.
It is known that conducted RF signals have a metallic component to the largely longitudinal signal. It
is caused by either the imbalance in twisted pair outside cable, or the differential pickup in quad
inside wire. The T-LISN specified is not perfectly balanced and is a rough simulation of the
cable situation. As T-LISNs with better balance are introduced, simulation of the cable
imbalance should be added to the test circuit.
Informative References
The following references, although not normative, contain information that provided background to
the original Standard.
1. Crawford, M. L. and Workman, J. L., Using a TEM cell for EMC measurements of electronic
equipment, National Bureau of Standards, NBS technical note 1013, April 1979.
2. Hansen, D., Wilson, P., Königstein, D., Garbe, H., Emission and Susceptibility Testing in a
Tapered TEM Cell, 8th International Zürich Symposium on EMC 1989, pp. 227-232, Zürich,
Switzerland, March 1989.
3. Bell Canada Technical Advisory Document (TAD) 8465, Issue 1, Electromagnetic Compatibility
Requirements and Test Methods for Telecommunications Equipment and Systems, April 1992.
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SP-3-3210-RV2
(To be published as ANSI/TIA-631-B)
ANNEX E – EXTENSION TO PRODUCTS OTHER THAN HANDSET TELEPHONES
The test procedures and requirements in the body of this standard are only defined for two-wire
analog telephones with handsets. The extension of these test procedures to other two-wire analog
telephone products, such as speakerphones, answering systems, and telephones with headsets, is
discussed below.
Far-End Send Measurements
In principal, the far-end send (transmit) immunity measurements for a speakerphone, answering
system, or telephone equipped with a headset should be no different than for a telephone equipped
with a handset. Therefore, no fundamental change in test procedure is required for these products,
and the same performance criteria can be applied.
However, it may be necessary to ensure speakerphones are in their full on send mode. This can
sometimes be achieved by strapping options internal to the speakerphone. Otherwise, it can be
accomplished by generating a speech-like signal in the vicinity of the speakerphone, momentarily
interrupting it, and checking the tip/ring interface for a demodulated 1000 Hz signal during the 200
ms or so of speakerphone hangover time after the speech-like signal is removed.
Answering systems should be tested both while playing an outgoing announcement and while
recording an incoming message. Again, it may be necessary to intersperse sections of speech-like
signal being played back or recorded with periods of silence and check for a demodulated 1000 Hz
signal on tip/ring during the silent intervals.
If telephones equipped with headsets employ voice-switched gain, then it may be necessary to
employ procedures like those described for speakerphones to ensure the gain is in the full on send
mode.
Near-End Receive Measurements
Near-end receive measurements on handset telephones are made with the receive volume control set
to the reference Receive Loudness Rating (RLR) as specified in TIA-470.110-C for analog
telephones. The performance criteria are specified in terms of the allowed 1000 Hz sound pressure
produced by the handset receiver with this specified volume control setting.
The allowed limits are 55 dBSPL (-39 dBPa) across the entire 150 kHz to 150 MHz band specified
for the RF signal. There is also a “should” requirement that is 10 dB more stringent (45 dBSPL, or –
49 dBPa) in the 500 kHz to 2 MHz band that primarily encompasses AM radio signals. For
reference, a 500-type telephone tested on a Type 1 artificial ear will put out about 90 dBSPL (-4
dBPa) at 1000 Hz when tested on a 9 kft 26 AWG loop with an applied open circuit voltage of –10
dBVoc at the CO. So the mandatory and desirable performance limits are 35 dB and 45 dB,
respectively, below this reference condition.
For RF immunity testing of a speakerphone, it is first necessary to establish its acoustic output for an
equivalent reference condition, and then determine if any demodulated 1000 Hz RF signal is
sufficiently below this reference level. Since a –10 dBVoc input level is artificially high when it
comes to real network signal levels, a –15 dBVoc test level should be used for establishing the
reference speakerphone output in order to avoid signal clipping. As a result, the requirements for the
demodulated 1000 Hz RF signal should be reduced to 30 dB (Mandatory) or 40 dB (Desirable) below
the reference acoustic output level measured when a 1000Hz signal at –15 dBVoc is applied to the
speakerphone on a 9 kft 26 AWG loop. A mid-range volume control setting should be used for this
test. However, unless the RF demodulation occurs between the output amplifier and the loudspeaker
34
(To be published as ANSI/TIA-631-B)
SP-3-3210-RV2
transducer of the speakerphone (not a likely occurrence), the actual volume control setting is not
critical.
To summarize, the output of the speakerphone is first determined using a mid-range volume control
setting with a 1000 Hz input signal of –15 dBVoc applied at the CO end of a 9 kft loop. This is used
as the reference acoustic level. Using the same volume control setting, the speakerphone is then
subjected to a radiated or conducted RF signal in the same manner as a handset telephone, and the
demodulated 1000 Hz acoustic output is measured. The limits on the demodulated 1000 Hz acoustic
output are that it “shall” be at least 30 dB below the reference level over the 150 kHz to 150 MHz RF
frequency range, and it “should” be at least 40 dB below the reference level over the 500 kHz to 2
MHz RF frequency range. The 5 dB less stringent requirements reflect the 5 dB lower input level for
establishing the reference acoustic level.
Of course, all acoustic measurements are to be made with an acoustic coupling tube applied to the
speakerphone’s loudspeaker in a manner analogous to that used for measuring the output of a handset
receiver. This includes the determination of the reference level as well as the measurement of the
demodulated 1000 Hz RF signal.
It is also necessary that the speakerphone be in the full on receive mode for this test. This may
sometimes be achieved by strapping options internal to the speakerphone. Otherwise, it can be
achieved by applying a speech-like signal to tip/ring, momentarily interrupting it, and checking for a
demodulated 1000 Hz acoustic signal during the 200 ms or so of hangover time after the speech-like
signal is removed.
The same principle applies for answering systems, except it is necessary to make the demodulated
measurements in both the local message playback and incoming message recording (call screening)
states. It may also be necessary to make sure the answering system is in a full on receive state when
checking the incoming message recording mode by interspersing periods of speech-like signal with
quiet intervals and checking for a demodulated 1000 Hz signal during the quiet interval.
Telephones with headsets are tested very much like telephones with handsets. In fact, the limits for
the demodulated acoustic level of a handset telephone (55 dBSPL mandatory, 45 dBSPL desirable in
the AM frequency band) may be applied to a telephone equipped with a headset if a reference
Receive Loudness Rating volume control setting has been established for the headset. Alternatively,
the process of establishing a reference acoustic level that is described for speakerphones may also be
used. The method chosen should be clearly stated.
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