Telecom Technical Specifications



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5.2 Handset function

5.2.1 Transmission objective reference equivalent

5.2.1.1 Sending objective reference equivalent (According to OREM-A specification)


Requirement: According to OREM-A specification, the sending objective reference equivalent shall be +11~ -2 dB when measured with the artificial line set to 0KM and +11 ~ 0 dB when measured with the artificial line set to 5KM.

Purpose: The TE have a objective reference equivalent compatible with other telephones connected to the network so as to be capable of providing adequate speech performance.

Test method:


  1. Sending objective reference equivalent test configuration as Fig.21.

  2. Sending objective reference equivalent test method:

  1. The Sending objective reference equivalent value shall be determined from measured frequency response curve using the calculation method described in OREM-A.

  2. The frequency response curve shall be measured over a range from at least 200Hz to 5000Hz in accordance with OREM-A method.

  3. The handset setup on artificial ear and mouth accordance with OREM-A method.

  4. Artificial line set to 0KM.

  5. The nominal sound pressure level produced by the artificial mouth shall be 0.6dBPa.

  6. Measure and record the Sending objective reference equivalent value from objective equivalent tester.

  7. Artificial line set to 5KM and Repeat step (5) to (6).


C=2μF±10%

Sound


attenuation

cover


600 Ω

Artificial

mouth

Signal Generator

Telephone handset

Speech network

Artificial line



Loop simulator

T

R

Rx

Tx

dB meter




C=2μF±10%

Amplifier

Figure 21 Sending objective reference equivalent test configuration


Test equipment:



  1. Signal Generator.

  2. Amplifier.

  3. Artificial mouth.

  4. Sound attenuation cover.

  5. Telephone handset Speech network.

  6. Artificial line.

7. Loop simulator.

8. dB meter : Objective reference equivalent meter or level recorder



5.2.1.2 Receiving objective reference equivalent (According to OREM-A specification)


Requirement: According to OREM-A specification, the receiving objective reference equivalent shall be 5 ~ -6 dB when measured with the artificial line set to 0KM and 5 ~ -4 dB when measured with the artificial line set to 5Km.

If the telephone handset has adjustable receive gain, it shall be set to provide the nominal output level.

Purpose: The TE have a objective reference equivalent compatible with other telephones connected to the network so as to be capable of providing adequate speech performance.

Test method:



  1. Receiving objective reference equivalent test configuration as Fig.22.

  2. Receiving objective reference equivalent test method:

  1. The receiving objective reference equivalent value shall be determined from measured frequency response curve using the calculation method described in OREM-A.

  2. The frequency response curve shall be measured over a range from at least 200Hz to 5000Hz in accordance with OREM-A method.

  3. The handset setup on artificial ear and mouth accordance with OREM-A method.

  4. Artificial line set to 0 KM.

  5. AC Signal generator be sent 285mv to artificial ear.

  6. Measure and record the receiving objective reference equivalent value from objective equivalent meter.

  7. Artificial line set to 5KM and Repeat step (5).


C=2μF±10%

Telephone handset

Speech network

Artificial line



AC signal

generator



Loop simulator

T

R

Rx

Tx

Artificial

ear


Amplifier

dB

Meter


Sound

attenuation

cover

C=2μF±10%


Figure 22 Receiving objective reference equivalent test configuration

Test equipment:


  1. dB meter : Objective reference equivalent meter or level recorder

  2. Amplifier.

  3. Sound attenuation cover.

  4. Artificial ear.

  5. Telephone handset Speech network.

6. Artificial line.

7. Loop simulator.

8. AC signal generator.

5.2.2 Transmission characteristics frequency response

5.2.2.1 Sending frequency response (According to OREM-A specification)


Requirement: According to OREM-A specification, the sending frequency response, as a function of frequency, shall be not greater than the upper limit and not less than the lower limit shown in figure 23 between 180 Hz to 5000 Hz. The 1000 Hz point on the frequency response graph is to be placed at the 0dB level on Fig.23 when measured with the artificial line set to 0KM.

Purpose: The TE have a frequency response compatible with the network and with other telephones connected to the network so as to be capable of providing adequate speech performance.

Test method:

1. Sending frequency response test configuration as Fig.21.

2. Sending frequency response test method:


  1. The handset setup on artificial ear and mouth accordance with OREM-A method.

  2. Artificial line set to 0KM.

  3. The nominal sound pressure level produced by the artificial mouth shall be 0.6dBPa.

  4. The frequency response curve shall be measured in a range of 200 Hz to 5kHz in according to OREM-A method.

  5. Measure and record the sending frequency response.

Test equipment:

  1. Signal Generator.

  2. Amplifier.

  3. Artificial mouth

  4. Sound attenuation cover

  5. Telephone handset Speech network.

  6. Artificial line.

  7. Loop simulator.

  8. dB meter: Objective reference equivalent metor (OREM) or level recorder.



5.2.2.2 Receiving frequency response (According to OREM-A specification)


Requirement: According to OREM-A specification, the receiving frequency response, as a function of frequency, shall be not greater than the upper limit and not less than the lower limit shown in figure 24 between 240 Hz to 5000 Hz. The 1000 Hz point on the frequency response graph is to be placed at the 0dB level on Fig.24 when measured with the artificial line set to 0KM.

If the telephone handset has adjustable receive gain, and when the volume control is set to nominal output level and maximum output level shall be meet this requirement.

Purpose: The TE have a frequency response compatible with the network and with other telephones connected to the network so as to be capable of providing adequate speech performance.

Test method:

1. Receiving frequency response test configuration as Fig.22.

2. Receiving frequency response test method:



  1. The handset setup on artificial ear and mouth accordance with OREM-A method.

  2. Artificial line set to 0KM.



2dB

12dB/Oct.

-14.5dB

-11dB

-4dB

12dB/Oct.

180

200

300

1000

2000

3000

4500

5000

12dB/Oct.

14dB

6dB/Oct.

18dB/Oct.

+20

+10

-10

0

-20

dB


Frequency (Hz)

Figure 23: Frequency Response of Sending


2dB

18dB/Oct.

-10dB

-2dB

240

500

1000

3000

Frequency (Hz)

4500

5000

2dB/Oct.

8.5dB

5.5dB

18dB/Oct.

3dB/Oct.

5dB/Oct.

3dB/Oct.

24dB/Oct.

+20

+10

-10

0

-20

dB

Figure 24: Frequency Response of Receiving



  1. AC Signal generator be sent 285mv to artificial ear.

  2. The frequency response curve shall be measured in a range of 200 Hz to 5kHz in accordance with OREM-A method.

  3. Measure and record the receiving frequency response.

Test equipment:

  1. dB meter : Objective reference equivalent meter or level recorder

  2. Amplifier.

  3. Sound attenuation cover.

  4. Artificial ear.

  5. Telephone handset Speech network.

  6. Artificial line.

  7. Loop simulator.

  8. dB meter: Objective reference equivalent meter (OREM) or level recorder.


5.2.3 Side-tone objective reference equivalent (According to OREM-A specification)


Requirement: According to OREM-A specification, the side-tone objective reference equivalent shall be ≧ 4 dB when measured with the artificial line set to 0KM and 5KM.

If the telephone handset has adjustable receive gain, it shall be set to provide the nominal output level.

Purpose: The TE have a side-tone performance which neither disturbs the user nor interferes with the speech levels to such an extent as to render the telephone incompatible with adequate speech performance.

Test method:



  1. Side-tone objective reference equivalent test configuration as Fig.25.


C= 2μF±10%

Telephone handset

Speech network

Artificial line

600 ohms

Loop simulator

T

R

Rx

Tx

Artificial

mouth


Amplifier

Artificial

ear


Amplifier

dB Meter

C =2μF±10%


Signal


Generator

Figure 25 Side-tone objective reference equivalent test configuration




  1. Side-tone objective reference equivalent test method:

  1. The side-tone objective reference equivalent shall be measured according to OREM-A method.

  2. The handset setup on artificial ear and mouth accordance with OREM-A method.

  3. The sound presure level of artificial mouth be produced 0.6dBa, frquency is from 200Hz to 5kHz

  4. Artificial line set to 0KM.

  5. Measure and record the side-tone objective reference equivalent value from objective equivalent tester.

  6. Artificial line set to 5KM and Repeat step (4).

Test equipment:

  1. Sinal generator.

  2. Amplifier  2.

  3. Artificial ear.

  4. Artificial mouth.

  5. Telephone handset Speech network.

  6. Artificial line.

  7. Loop simulator.

  8. dB meter: Objective reference equivalent meter (OREM) or level recorder.



5.2.4 Distortion

5.2.4.1 Sending distortion (According to OREM-A specification)


Requirement: The total distortion in the electric output signal of transmitter to telephone line shall not exceed 5% when measured with the artificial line set to 0KM.

Purpose: The TE not to produce distortion of the transmitted speech signals sufficient to interfere with adequate speech performance.

Test method:


  1. Sending distortion test configuration as Fig.26.

  2. Sending distortion test method:

  1. The handset setup on artificial ear and mouth accordance with OREM-A method.

  2. Artificial line set to 0KM.

  3. The artificial mouth sound pressure level shall be set to 0dBPa at 1000 Hz.

  4. Measure and record the sending distortion from distortion meter.


C = 2μF±10%

Sound


attenuation

cover


C = 2μF±10%

Figure 26 Sending distortion test configuration

Telephone handset

Speech network

600 ohms

Distortion analyzer

Loop simulator

T

R

Rx

Tx

Artificial

mouth


Amplifier

Signal Generator

Artificial line

Test equipment:



  1. Signal Generator.

  2. Amplifier.

  3. Artificial Ear.

  4. Artificial mouth.




  1. Telephone handset Speech network.

  2. Loop simulator

  3. Distortion analyzer.

  4. Artificial line



5.2.4.2 Receiving distortion (According to OREM-A specification)


Requirement: The total distortion of receiver shall not exceed 7% when measured with the artificial line set to 0KM.

If the telephone handset has adjustable receive gain, the total distortion of receiver shall not exceed 10% when the volume control set to maximum output level.

Purpose: The TE not to produce distortion of the received speech signals sufficient to interfere with adequate speech performance.

Test method:

1. Receiving distortion test configuration as Fig.27.

2. Receiving distortion test method:



  1. The handset setup on artificial ear and mouth accordance with OREM-A method.

  2. Artificial line set to 0KM.

  3. The signal generator shall be set to –12dBv / 1000 Hz. Sine wave to EUT.

  4. Measure and record the receiving distortion from distortion meter.

  5. If the EUT has the function of increasing receiver gain, set the voice level in the maximum and repeat step(4).


C =2μF±10%

Artificial Ear






Amplifier


Distortion

meter

Sound


attenuation

cover


Telephone handset

Speech network



AC signal generator

Loop simulator

T

R

Rx

Tx

Figure 27 Receiving distortion test configuration

Artificial line







C =2μF±10%




Test equipment:

  1. Signal Generator.

  2. Distortion meter

  3. Amplifier

  4. Artificial era

  5. Sound attenuation cover

  6. Telephone handset speech network

  7. Loop simulator

  8. Artificial line

5.2.5 Receiver volume control


Requirement: If the telephone handset has adjustable receive gain, it shall be provide 3dB of gain minimum and up to 6dB of gain maximum when measured in term of receiving objective reference equivalent.

The 6dB of gain maximum may be exceed if the receiver volume is automatically restored to its nominal value when the TE is returned to the on-hook state.

Purpose: To provide adequate speech receiving performance with other TE in connected through the network.

Test method:



  1. Receiver volume control test configuration as Fig.22.

  2. Receiver volume control test method:

  1. Artificial line set to 0KM.

  2. Receiver volume control set to minimum condition.

  3. Measure and record receiving objective reference equivalent. SORE1 according to section 5.2.1.2.

  4. Receiver volume control adjusted to maximum condition and repeated step (3) then get the SORE2.

  5. Calculate the receive gain = SORE2 – SORE1.

  6. Artificial line adjusted to 5KM and repeated step (2) to (5).

Test equipment:

1. Signal generator.

2. Amplifier.

3. Artificial ear.

4. Sound attenuation cover.

5. Telephone handset Speech network.

6. Artificial line.

7. Loop simulator.

8. dB meter: Objective reference equivalent meter (OREM) or level recorder.

5.2.6 Continuous sound pressure level of receiver


Requirement: In the off-hook mode, rms acoustic pressure of receiver shall be less than 125 dB(A).

If the telephone handset has adjustable receive gain, it shall be meet this requirement when volume control set to maximum output level.

Purpose: To protect the user not hurt in hearing function.

Test method:



  1. Continuous sound pressure level of receiver test configuration as Fig.28.

  2. Continuous sound pressure level of receiver test method:

  1. Set the sound level amplifier to provide “A” weighting and “slow” response.

  2. EUT set off-hook state and adjust variable resistor to give a loop current 30mA.

  3. Set the signal generator to give an output 4.0Vrms into an open circuit at a frequency of 1000 Hz.

  4. Sweep the signal generator frequency from 180 Hz to 10 kHz.

  5. Measure and record the maximum acoustic output reading of receiver during the frequency sweep.

C = 2μF±10%



Sound level meter


A

Telephone handset

Speech network

Signal generator

Loop simulator

R

T

Rx

Sound

attenuation

cover

Tx

Artificial

ear


Amplifier

C = 2μF±10%


Figure 28 Continuous sound pressure level of receiver test configuration



Test equipment:

  1. Sound level meter.

  2. Artificaial ear.

  3. Sound attenuation cover.

  4. Telephone handset Speech network.

  5. DC current meter.

  6. Loop simulator

  7. Signal generator.




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