CS-03, Part VII — Requirements for Limited Distance Modems and Digital Subrate Terminal Equipment

3.0 Network ProtectionRequirements and Tests

3.1 Requirements and Test Methods for Limited-Distance Modem Terminal Equipment

3.1.1 Signal Level Limitations

3.1.1.1 Requirements

The metallic voltage shallcomply with the general requirements in (1) below, as well as with the requirementsspecified in (2) and (3) as stated. The requirements apply under the conditionsspecified in Section 3.1.2. TE for which the magnitude of the source and/orterminating impedance exceeds 300 ohms, at any frequency in the range of 100 kHz to 6 MHz, at which thesignal (transmitted and/or received) has significant power, shall be deemed notto comply with these requirements. A signal is considered to have 'significant power' at a given frequency if thatfrequency is contained in a designated set of frequency bands whichcollectively have the property that the root-mean-square (rms) voltage of thesignal components in those bands is at least 90% of the rms voltage of thetotal signal. The designated set of frequency bands must be used in testing all frequencies.

  1. Metallic Voltages – Frequencies Below 4 kHz
    1. Weighted rms Voltage in the 10 Hz to 4 kHz Frequency Band

      The weighted rms metallic voltage averaged over 100 milliseconds (frequency components weighted in accordance with the transfer function F/4000) shall not exceed the maximum indicated below:

      Weighted rms Voltage in the 10 Hz to 4kHz Frequency Band
      Frequency Range Maximum Voltage
      10 Hz to 4 kHz +3 dBV
    2. rms Voltage in 100 Hz Bands in the Frequency Range 0.7 kHz to 4 kHz

      The rms metallic voltage averaged over 100 milliseconds in the 100 Hz bands having centre frequencies between 750 Hz and 3950 Hz shall not exceed the maximum indicated below:

      rms voltage in 100 Hz Bands in the Frequency Range 0.7 kHz to 4 kHz
      Centre Frequency (f) of 100 Hz Bands Maximum Voltage
      750 Hz to 3950 Hz -6 dBV
  2. MetallicVoltages – Frequencies Above 4 kHz – LDM Interface
    1. 100 HzBands Within Frequency Range 4 kHz to 270 kHz

      The rms voltage,as averaged over 100 milliseconds in all possible 100 Hz bands between 4 kHzand 270 kHz for the indicated range of centre frequencies and under theconditions specified in Section 3.1.4, shall not exceed the maximum indicated below:

      100 Hz Bands Within Frequency Range 4 kHz to 270 kHz
      Centre Frequency (f) of 100 Hz Bands Maximum Voltage in all 100 Hz Bands
      4.05 kHz to 4.60 kHz 0.5 dBV
      4.60 kHz to 5.45 kHz (59.2-90 log f) dBV
      5.45 kHz to 59.12 kHz (7.6-20 log f) dBV
      59.12 kHz to 266.00 kHz (43.1-40 log f) dBV

      where f =centre frequency in kHz of each of the possible 100 Hz bands.

    2. 8 kHz Bands Within Frequency Range 4 kHz to 270 kHz

      The rms voltage,as averaged over 100 milliseconds in all of the possible 8 kHz bands between 4 kHzand 270 kHz for the indicated range of centre frequencies and under theconditions specified in Section 3.1.4, shall not exceed the maximum indicatedbelow:

      8 kHz Bands Within Frequency Range 4 kHz to 270 kHz
      Centre Frequency (f) of 8 Hz Bands Maximum Voltage in all 8 Hz Bands
      8 kHz to120 kHz (17.6-20 log f) dBV
      120 kHz to 266 kHz (59.2-40 log f) dBV

      Where f = centre frequency in kHz of each of the possible 8 kHz bands.

    3. rmsVoltage at Frequencies Above 270 kHz

      The rms valueof the metallic voltage components in the frequency range of 270 kHz to 30 MHzshall, averaged over 2 microseconds, not exceed -15 dBV. This limitationapplies with a metallic termination having an impedance of 135 ohms.

    4. Peak Voltage

      The total peakvoltage for all frequency components in the 4 kHz to 30 MHz band shall not exceed 4.0 volts.

  3. Longitudinal Voltage

    Requirement

    1. Frequencies Below 4 kHz

      With the frequency componentsweighted in accordance with the transfer function f/4000, the weighted rmsvoltage of all frequency components, in the frequency band from 10 Hz to 4 kHz,averaged over 100 milliseconds, shall not exceed the maximum indicated belowunder the conditions stated in Section 3.1.4.

      Frequencies Below 4 kHz
      Frequency Range Maximum RMS Voltage
      10 Hz to 4 kHz -37 dBV

      Where f =centre frequency in kHz of each of the possible 8 kHz bands.

    2. Frequenciesfrom 4 kHz to 270 kHz
      Frequencies from 4kHz to 270 kHz
      Centre Frequency (f) of 8 kHz Band Maximum Voltage in all 8 kHz Bands Longitudinal Terminating Impedance
      8 kHz to 12 kHz -(18.4+20 log f) dBV 500 ohms
      12 kHz to 42 kHz (3-40 log f) dBV 90 ohms
      42 kHz to 266 kHz -62 dBV 90 ohms

      Where f =centre frequency in kHz of each of the possible 8 kHz bands.

    3. Frequenciesfrom 270 kHz to 6 MHz

      The rms valueof the longitudinal voltage components in the frequency range of 270 kHz to 6 MHz shall, averaged over 2 microseconds, not exceed -30 dBV. This limitationapplies with a longitudinaltermination having an impedance of 90 ohms.

3.1.2 Equipment Conditions Subject to Test

  1. Except during the transmission of ringing and dual tone multi-frequency (DTMF) signals, LDM TE shall comply with all requirements in all operating states and with loop current, which may be drawn for such purposes as loop back signalling. The requirements in Section 3.1.1.1(1) except in paragraphs (a) and (b) also apply during the application of ringing. The requirement in Section 3.1.1.1(1)(a) and (b) apply during ringing for frequencies above 300 Hz and with the maximum voltage limits raised by 10 dB. DTMF signals, which are used for the transmission of alphanumeric information and which comply with the requirements in Section 3.1.1.1(1)(a) and in Section 3.1.1.1(2) or (3) as applicable, shall be deemed to comply with the requirements in Section 3.1.1.1(1)(b) provided that, for automatically originated DTMF signals, the duty cycle is less than 50 percent.
  2. LDM TE shall comply with all applicable requirements, except those specified in sections 3.1.1.1(1)(a) and (b), during the transmission of each possible data signal sequence of any length. For compliance with Section 3.1.1.1(3)(a), the limitation applies to the rms voltage averaged as follows:
    1. For digital signals, baseband or modulated on a carrier, for which there are defined signal element intervals, the rms voltage is averaged over each such interval. Where multiple carriers are involved, the voltage is the power sum of the rms voltages for the signal element intervals for each carrier.
    2. For baseband analog signals, the rms voltage is averaged over each period (cycle) of the highest frequency of the signal (3 dB point on the spectrum). For analog signals which are modulated on a carrier (whether or not the carrier is suppressed), it is averaged over each period (cycle) of the carrier. Where multiple carriers are involved, the voltage is the power sum of the rms voltage for each carrier.
    3. For signals other than the types defined above in sections 3.1.2(2)(a) and (b), the peak amplitude of the signal must not exceed +1 dBV.
  3. Equipment shall comply with the requirements in sections 3.1.1.1(1)(a) and (b) during any data sequence which may be transmitted during normal use with a probability greater than 0.001. If the sequences transmitted by the equipment are application dependent, the user instruction material shall include a statement of any limitations assumed in demonstrating compliance of the equipment.
  4. In addition to the conditions specified in paragraph (1) of this section, LDM TE which operates in one or more modes as a receiver, shall comply with requirements in Section 3.1.1.1(3) with a tone at all frequencies in the range of potential received signals and at the maximum power which may be received.

3.1.3 Method of Measurement (Metallic)

Note: Refer to Section 3.1.2 for applicable test conditions.

3.1.3.1 Frequencies Below 4 kHz (see Section 3.1.1.1(1)(a))

  1. Connect the TE to the test circuit of Figure 3.1.3(a).
  2. Select the 10 Hz to 4000 Hz band pass filter.
  3. Cause the TE to transmit an output signal in accordance with sections 3.1.2(2) and (3).
  4. Record the voltmeter reading.
  5. Repeat steps (3) and (4) for all possible states.

    Note: The remaining steps are only applicable to 4-wire TE.
  6. Connect the TE to the test circuit of Figure 3.1.3(b).
  7. Select the 10 Hz to 4000 Hz band pass filter.
  8. Repeat steps (3) through (5).

3.1.3.2 100 Hz Bands in the Frequency Range 0.7 kHz to 4 kHz (see Section 3.1.1.1(1)(b)) and 100 Hz Bands in the Frequency Range 4 kHz to 270 kHz (see Section 3.1.1.1(2)(a))

  1. Connect the TE to the test circuit of Figure 3.1.3(c).
  2. Cause the TE to transmit an output signal in accordance with sections 3.1.2(2) and (3).
  3. Measure the rms voltage averaged over 100 ms with a bandwidth of 100 Hz.
  4. Record the highest measured value and its associated frequency and any test results that exceed -6 dBV for centre frequencies in each 100 Hz band between 750 Hz and 3950 Hz.
  5. Record the highest measured value and its associated frequency and any test results that exceed -5 dBV for centre frequencies in each 100 Hz band between 4.05 kHz and 4.60 kHz.
  6. Compare the results with the allowed limit for each 100 Hz band having a centre frequency between 4.60 kHz and 5.45 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  7. Compare the results with the allowed limit for each 100 Hz band having a centre frequency between 5.45 kHz and 59.12 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  8. Compare the results with the allowed limit for each 100 Hz band having a centre frequency between 59.12 kHz and 266 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  9. Repeat steps (2) through (8) for all operating conditions.

    Note: The remaining steps are only applicable to 4-wire TE.
  10. Connect the TE to the test circuit of Figure 3.1.3(d).
  11. Repeat steps (2) through (9).

3.1.3.3 8 kHz Bands in the Frequency Range 4 kHz to270 kHz (see Section 3.1.1.1(2)(b))

  1. Connect the TE to the test circuit of Figure 3.1.3(c).
  2. Cause the TE to transmit an output signal in accordance with sections 3.1.2(2) and (3).
  3. Measure the rms voltage averaged over 100 ms with a bandwidth of 8 kHz.
  4. Compare the results with the allowed limit for each 8 kHz band having a centre frequency between 8 kHz and 120 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  5. Compare the results with the allowed limit for each 8 kHz band having a centre frequency between 120 kHz and 266 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  6. Repeat steps (2) through (5) for all operating conditions.

    Note: The remaining steps are only applicable to 4-wire TE.
  7. Connect the TE to the test circuit of Figure 3.1.3(d).
  8. Repeat steps (2) through (6).

3.1.3.4 rms Voltages at Frequencies Above 270 kHz (see Section 3.1.1.1(2)(c))

  1. Connect the TE to the test circuit of Figure 3.1.3(e).
  2. Select the 270 kHz to 30 MHz band pass filter.
  3. Set the digital oscilloscope to provide:
    1. 2 μs per sample;
    2. trigger at -25 dBV;
    3. peak capture; and
    4. vertical scale 0 mV to 100 mV full height.

    Note: If the baseline contains 1000 points, a single trace will take 2 ms.

  4. Program the oscilloscope to accumulate 10 traces.
  5. Set the TE to transmit an output signal in accordance with Sections 3.1.2(2) and (3).
  6. Record the value of the largest peak measured and convert to Vrms by multiplying by 0.707.

    Note: The remaining steps are only applicable to 4-wire TE.
  7. Connect the TE to the test circuit of Figure 3.1.3(f).
  8. Repeat steps (2) through (6).

3.1.3.5 Peak Voltages at Frequencies above 4 kHz (see Section 3.1.1.1 (2)(d))

  1. Connect the TE to the test circuit Figure 3.1.3(e).
  2. Select the 4 kHz to 30 MHz band pass filter.
  3. Set the digital oscilloscope to provide:
    1. 2 μs per sample;
    2. trigger at 0.4 V peak;
    3. peak capture; and
    4. vertical scale 0 V to 5 V full height.
  4. Accumulate peak readings for a 10-second period.
  5. Set the TE to transmit an output signal in accordance with sections 3.1.2(2) and (3).
  6. Record the value of the largest peak measured.

    Note: The remaining steps are only applicable to 4-wire TE.
  7. Connect the TE to the test circuit of Figure 3.1.3(f).
  8. Repeat steps (2) through (6).
Figure 3.1.3(a): LDM Metallic 10 Hz to 4 kHz, tip and ring
Figure 3.1.3(a): LDM Metallic 10 Hz to 4 kHz, tip and ring

[Description of Figure]

Figure 3.1.3(b): LDM Metallic 10 Hz to 4 kHz, T1 & R1
Figure 3.1.3(b): LDM Metallic 10 Hz to 4 kHz, T1 and R1

[Description of Figure]

Figure 3.1.3(c): LDM Metallic 4 kHz to 270 kHz, T & R
Figure 3.1.3(c): LDM Metallic 4 kHz to 270 kHz, T and R

[Description of Figure]

Note: The spectrum analyzer should provide a balanced input, or an isolation transformer should be used.

Figure 3.1.3(d): LDM Metallic 4 kHz to 270 kHz, T1 & R1
Figure 3.1.3(d): LDM Metallic 4 kHz to 270 kHz, T1 and R1

[Description of Figure]

Note: The spectrum analyzer should providea balanced input, or an isolation transformer should be used.

Figure 3.1.3(e): LDM Metallic 270 kHz to 30 MHz, T & R
Figure 3.1.3(e): LDM Metallic 270 kHz to 30 MHz, T and R

[Description of Figure]

Figure 3.1.3(f): LDM Metallic 270 kHz to 30 MHz, T1 & R1
Figure 3.1.3(f): LDM Metallic 270 kHz to 30 MHz, T1 and R1

[Description of Figure]

3.1.4 Method of Measurement Longitudinal

Note: Refer to Section 3.1.2 for applicable test conditions.

3.1.4.1 Frequencies Below 4 kHz (3.1.1.1 (3)(a))

  1. Connect the TE to the test circuit of Figure 3.1.4(a).
  2. Set the TE to transmit an output signal in accordance with sections 3.1.2(2) and (3).
  3. Record the maximum spectrum analyzer reading in the test band.
  4. Repeat steps (2) and (3) for all possible states.

    Note: The remaining steps are only applicable to 4-wire TE.
  5. Connect the TE to the test circuit of Figure 3.1.4(b).
  6. Repeat steps (2) through (4).

    Note: The measured result shall be corrected +3.1 dB for the voltage divider relationship of the termination.

3.1.4.2 8 kHz Bands Over the Frequency Range of 4 kHz to 270 kHz (3.1.1.1(3)(b))

  1. Connect the TE to the test circuit Figure 3.1.4(c).
  2. Select R1=R2=150 ohms and R3=425 ohms.
  3. Cause the TE to transmit an output signal in accordance with paragraphs 3.1.2(2) and (3).
  4. Measure the rms voltage averaged over 100 ms with a bandwidth of 8 kHz covering the frequency range of 4 kHz to 16 kHz.

    Note: The measured result shall be corrected for the voltage divider relationship of the termination. Adjustment is +1.4 dB.
  5. Compare the results with the allowed limit for each 8 kHz band having a centre frequency between 8 kHz and 12 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  6. Select R1=R2=67.5 ohms and R3=56.3 ohms.
  7. Cause the TE to transmit an output signal in accordance with paragraphs 3.1.2(2) and (3).
  8. Measure the rms voltage averaged over 100 ms with a bandwidth of 8 kHz covering the frequency range of 8 kHz to 46 kHz.

    Note: The measured result shall be corrected for the voltage divider relationship of the termination. Adjustment is +4.0 dB.
  9. Compare the results with the allowed limit for each 8 kHz band having a centre frequency between 12 kHz and 42 kHz, and record the measured value having the smallest margin relative to the allowed limit and its frequency.
  10. Measure the rms voltage averaged over 100 ms with a bandwidth of 8 kHz covering the frequency range 38 kHz to 270 kHz.

    Note: The measured result shall be corrected for the voltage divider relationship of the termination. Adjustment is +4.0 dB.
  11. Record the highest measured value and its associated frequency and any test results that exceed -62 dBV for centre frequencies in each 8 kHz band between 42 kHz and 266 kHz.
  12. Repeat steps (2) through (11) for all operating conditions.

    Note: The remaining steps are only applicable to 4-wire TE.
  13. Connect the TE to the test circuit of Figure 3.1.4(d).
  14. Repeat steps (2) through (12) for all operating conditions.

3.1.4.3 RMS Voltages at Frequencies Above 270 kHz (3.1.1.1(3)(c))

  1. Connect the TE to the test circuit of Figure 3.1.4(e).
  2. Select the 270 kHz to 6 MHz band pass filter.
  3. Set the digital oscilloscope to provide:
    1. 2 μs per sample;
    2. trigger at -25 dBV;
    3. peak capture; and
    4. vertical scale 0 mV to 100 mV full height.

    Note: If the baseline contains 1,000 points, a single trace will take 2 ms.
  4. Program the oscilloscope to accumulate 10 traces.
  5. Set the TE to transmit an output signal in accordance with paragraphs 3.1.2(2) and (3).
  6. Record the value of the largest peak measured and convert to V rms by multiplying by 0.707.

    Note: The remaining steps are only applicable to 4-wire TE.
  7. Connect the TE to the test circuit of Figure 3.1.4(f).
  8. Repeat steps (2) through (6).

    Note: The measured result of step (7) shall be corrected +4 dB for the voltage divider relationship of the termination.
Figure 3.1.4(a): LDM Longitudinal Voltage 10 Hz to 4 kHz, T & R
Figure 3.1.4(a): LDM Longitudinal Voltage 10 Hz to 4 kHz, T & R

[Description of Figure]

Note: Means should be used to ensureproper operation of the TE while the pair under test is not connected tothe companion TE. All resistors are ±1% tolerance, 1 W.

Figure 3.1.4(b): LDM Longitudinal Voltage 10 Hz to 4 kHz, T1 & R1
Figure 3.1.4(b): LDM Longitudinal Voltage 10 HZ to 4 kHz, T1 & R1

[Description of Figure]

Note: Means should be used to ensure proper operation ofthe TE while the pair under test is not connected to the companion TE. All resistors are ± 1% tolerance, 1 W.

Figure 3.1.4(c): LDM Longitudinal Voltage 4 kHz to 270 kHz, T & R
Figure 3.1.4(c): LDM Longitudinal Voltage 4 kHz to 270 kHz, T & R

[Description of Figure]

Note: Means should be used to ensure proper operation ofthe TE while the pair under test is not connected to the companion TE. All resistors are ± 1% tolerance, 1 W.

Figure 3.1.4(d): LDM Longitudinal Voltage 4 kHz to 270 kHz, T1 & R1
Figure 3.1.4(d): LDM Longitudinal Voltage 4 kHz to 270 kHz, T1 & R1

[Description of Figure]

Note: Means should be used to ensure proper operation of theTE while the pair under test is not connectedto the companion TE. All resistors are ± 1% tolerance, 1 W.

Figure 3.1.4(e): LDM Longitudinal Voltage 270 kHz to 6 MHz, T & R
Figure 3.1.4(e): LDM Longitudinal Voltage 270 kHz to 6 MHz, T & R

[Description of Figure]

Note: Means should be used to ensure proper operation of the TE while the pair under test is not connected to the companion TE. All resistors are ± 1% tolerance, 1 W.

Figure 3.1.4(f): LDM Longitudinal Voltage 270 kHz to 6 MHz, T1 & R1
Figure 3.1.4(f): LDM Longitudinal Voltage 270 kHz to 6 MHz, T1 & R1

[Description of Figure]

Note: Means should be used to ensure proper operation of the TE while the pair under test is not connected to the companion TE. All resistors are ±1%tolerance, 1 W.