Telecom Technical Specifications




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2.Definition、Symbols and Abbreviations

2.1 Definition


Terminal Equipment: Equipment which is used in connecting to public switched telephone network for getting telephone communication service.

Loop Simulator: Simulated Circuit used in supplying DC loop current for testing.

Reference Load Impedance: A reference load impedance used in general test case of this technical requirement. 600Ω is used in general case, unless defined in special case of test. See Appendix.

Artificial Transmission Line: A simulated circuit used in test case to simulate the impedance and loss of telephone network.

Automatic dialing: Automatic dialing is defined as the process whereby the dialing information is automatically transmitted after seizure of a line.

Automatic line seizure: Automatic line seizure refers to seizure of the line not immediately succeeding a manual operating procedure:

Automatic repeat call attempts : An automatic repeated call, of the same number that is failure at last call.

Call attempt: A procedure of TE in sending the call address number.

Communication state: The communication state commences after dialing, in the case of an outgoing call, or commences after answering of the call, in the case of an incoming call and ends with the transition of the terminal equipment to the quiescent state.

Connection to earth: A terminal of equipment used in connecting with Ground wire of power outlet or a connection point on the equipment used in connecting to Ground while been test.

Dialing: Dialing begins with the emission of the first digit and ends with the last digit necessary for establishment of the call.

Dialing state: The dialing state is the operating state from the beginning to the end of the transmission of dialing information.

Inter-digital state: The inter-digital state commences on conclusion of the emission of one digit and ends when emission of the next digit commences or with the beginning of the communication states, as appropriate.

Longitudinal Conversion Loss: The measure of impedance is balanced to earth.

Network Termination Point (NTP): The physical connecting points to the Network.

Off hook condition: The off-hook condition commences when the terminal equipment has reached the stationary dc resistance level and ends with the transition to the dialing state or the quiescent state.

Operating states: The following operating states exist: quiescent state, off-hook condition, dialing state, inter-digital state, communication state, ringing state as well as the transitions to these states.

Quiescent state: The quiescent state is characterized by the fact that the terminal equipment is neither in a transient state nor in the dialing, ringing, off-hook, inter-digital or communication states.

Return Loss: Of the TE, a description of impedance is matching to PSTN.

Ringing state: The ringing state commences with the reception of the first ringing signal and ends with the answering of the call or when no further ringing signals are received.

Switching signals: Switching signals are electrical characters for signaling between terminal equipment and equipment of the telephone network.

Telecommunication messages: Telecommunication messages are electrical signals generated by terminal

equipment and which are not required for communication with the telephone network.

Transient states: From the quiescent state to the off-hook condition of outgoing call, from the ringing state to the communication state incoming call or from the communication state to the quiescent state of call clearing.

Metallic voltage: The potential difference between the tip and ring connections.

Longitudinal voltage: One half of the vector sum of the potential difference between the tip connection and earth ground, and the ring connection and earth ground.



2.2 Symbols


Ω : ohm

dB : decibell

dBspl. : dB sound pressure level

a.c. : alternating current

d.c. : direct current

dBm : dB miliwatt

dBV : dB Volt

DTMF : Dual Tone Multiple Frequency

V : Voltage

mA : miliampare

R : Resistance

ZR : Reference impedance

ERP : Ear Reference Point

MRP : Mouth Reference Point

r.m.s : root mean square

RL : Return Loss


2.3 Abbreviations


ACTE : Automatic Call Transfer Equipment

DTMF : Dual Tone Multi-Frequency

HGP : DTMF High frequency Group Power

LGP : DTMF Low frequency Group Power

PBX : Private Branch Exchange system

PSTN : Public Switched Telephone Network

RVA : Recorded Voice Announcement

TE : Terminal Equipment



3.EMC Requirement


TE should comply with requirements of CNS 13438 C 6357(Information technology equipment, Radio)

Disturbance characterstics-Limits and methods of measurement) as EMC’s technolody requirement and testing

standard.

4.Safety Requirement


TE should comply with requirements of CNS14336 C 5268(Safety of information technology equipment)

Including overvoltage and sound pressure testing items as electric safety technology requirement and testing

standard.

5.Telecommunication requirement

5.1 Public switch telephone network interface requirement

5.1.1 Basic requirements


  1. The TE shall be an independent entity not belongs to Type 1 telecommunications enterprises and prohibited to modify Type 1 telecommunications enterprises equipment.

  2. Any additional functions shall not impact public telecom equipment switching, testing, transport and billing functions when TE is connected to Network.

  3. While the TE is damaged or malfunctioning, other connected equipment should be influenced continue to function properly.



5.1.2 Surge Protection


Voltage Wave-shape of Surge

Front Time ( Tf ) = 1.67 × T , where T is time from 30% to 90% of peak voltage.

Decay Time ( Td ): Time from virtual origin to 50% of peak voltage on trailing edge
The circuit diagram of Surge Generator:


R2=15Ω

*R3=25Ω

C2=0.2μF





R1=50Ω

C1=20μF

S1

S2




O


T:time from 30% to 90% of peak voltage

Tf = 1.67 × T

Td:Time from virtual origin to 50% of peak voltage on trailing edge
pen circuit voltage waveshape:


5.1.2.1 Telephone Line Surge Test:

5.1.2.1.1 Metallic Surge Test:

Requirement: After applying the metallic surge test, all the operational functions must work well.

  1. Metallic surge wave form:Front time〔Tf〕≦10μs、decay time 〔Td〕≧560μs and peak voltage≧800V, the surge generator should support over 100A peak current.

  2. Apply the above surge wave form on the tip and ring of telephone line, while EUT is at on-hook and any operational mode, and then change the polarity to test it again.

Purpose: To simulate induced metallic surge voltage on a telephone line which could result from lightning.

Test Method:



  1. Figure 1 shows the metallic surge test configuration.

  2. The method of metallic surge test

  1. Set the front time(Tf)、decay time(Td) and peak voltage of metallic surge wave form.

  2. Set EUT at on-hook mode.

  3. Apply one surge of each polarity between two leads.

  4. Record and check the functions of EUT.

  5. Set the EUT under each operational mode and repeat step (3) to (4).

Test equipment:

  1. Surge Generator.

  2. Loop Simulator.

Figure 1 Surge test configuration



5.1.2.1. 2 Longitudinal Surge Test:

Requirement: After applying the metallic surge test, all the operational functions must work well.

  1. Longitudinal surge wave form:Front time〔Tf〕≦10μs、decay time〔Td〕≧160μs and peak voltage≧1500V, the surge generator should support over 200A peak current.

  2. Apply the above surge wave form on the shorted tip and ring of telephone line about earth, while EUT is at on-hook and any operational mode, and then change the polarity to test it again.

Purpose: To simulate induced longitudinal surge voltage on a telephone line which could result from

lightning.

Test Method:


  1. Figure 1 shows the longitudinal surge test configuration.

  2. The method of metallic surge test

  1. Set the front time(Tf)、decay time(Td) and peak voltage of longitudinal surge wave form.

  2. Set EUT at on-hook mode.

  3. With two leads connected together, apply one surge of each polarity between leads and ground.

  4. Record and check the functions of EUT.

  5. Set the EUT under each operational mode and repeat step (3) to (4).

Test equipment:

  1. Surge Generator.

  2. Loop Simulator.

5.1.2.2 AC Power Line Surge Test:


Requirement: After applying the AC power surge test, all the operational functions must work well.

  1. AC power surge wave form:Front time (Tf)≦2μs、decay time (Td)≧10μs and peak voltage ≧2500V, the surge generator should support over 1000A peak current.

  2. Apply the above surge wave form on the tip and ring of telephone line, while EUT is powered on and off , and then change the polarity to test it three times.

Purpose: To simulate induced AC power surge voltage on a telephone line which could result from lightning.

Test Method:



  1. Figure 2 shows the AC power surge test configuration.

EUT

Surge

Simulator


AC Power Line




Figure.2 AC Power line surge test configuration




  1. The method of AC power surge test

    1. Set the front time(Tf)、decay time(Td) and peak voltage of AC power surge wave form.

    2. Power on EUT.

    3. Apply three times surge of each polarity between two leads.

    4. Record and check the functions of EUT.

    5. Power off EUT and repeat step (3) to (4).

Test equipment:

  1. Surge Generator.

  2. AC Power Source.



5.1.3 Line Polarity:


Requirement: The two polarity connections of TE to PSTN shall comply with the requirements of this technical standard.

Purpose: To make sure TE can work with the PSTN in two polarity connections.

Test method: Where tests with both polarity connections are needed for this regulation.

5.1.4 Leakage current limitations


Requirement: TE shall have a voltage applied to the combination of test points listed in the table 1.

  1. test point:All telephone connections.

  2. test point:All power connections.

  3. test point:All possible combinations of exposed conductive surfaces on the exterior of such equipment.

Gradually increase the voltage from zero to the values listed in Table 1 over a 30 seconds time period, then maintain the voltage for one minute. The current in the mesh formed by the voltage source and these points shall not exceed 10mA peak at any time during this 90-second interval.

Table 1: Voltages applied for various combinations of connection points



Voltage source connected between:

AC voltage value

(1) and (3)

1000V/60Hz

(1) and (2)

1500V/60Hz

(2) and (3)

1500V/60Hz

Purpose: To verify the integrity of the dielectric barrier between the network and power line and the equipment connections of the EUT.

Test method:


    1. Leakage current limitations Test Configuration as Fig.3.

    2. Leakage current limitations test method:

  1. Select the appropriate EUT test point, according to the table 1.

  2. Set EUT at on-hook.

  3. Gradually increase the test voltage from 0 to the level required for the connections under test in reference to Table 1(i.e. V1), over a 30-second period. Maintain the maximum voltage level during 60 seconds.

  4. Record the maximum current measured during this period.

  5. Calculate the the maximum leakage current = V2 ÷ 1000

  6. Repeat step (3) to (5) in each operational states.

  7. Change the different test point in table 1, repeat step (2) to (6).

Test equipment:

  1. Isolated Adjustable High Voltage Source.

  2. Voltmeters (V1 and V2).



Figure 3 Leakage current limitation test configuration

5.1.5 Insulation resistance


Requirement: The insulation resistance between the following test points shall be greater than 5 MΩwhile apply 100 Vdc on th EUT.

  1. TE with 2 wires:

    1. Telephone line, tip to ring.

    2. Telephone line, short tip with ring v.s. AC power.

    3. Telephone line, short tip with ring v.s. earth.

  2. Leased line TE with 4 wires:

    1. Telephone line, short tip with ring v.s. shorting of T1 with R1.

    2. Telephone line, short T/ T1 with R/R1 v.s. earth ground.

    3. Telephone line, short T/ T1 with R/R1 v.s. AC power.

Purpose: To check whether the TE presents a higher resistance characters between ground and power line and the equipment connections of the EUT.

Test method:



  1. Insulation resistance Test Configuration as Fig.4.

  2. Insulation resistance test method:

  1. Set EUT at on-hook state.

  2. Set the voltage to 100 Vdc.

  3. Connect output point to the tip an ring of telephone line.

  4. Measure and record the current. Calculate the insulation resistance = 100÷Idc.

  5. Connect output point to the test pints specified above one by one.

  6. Measure and record the current. Calculate the insulation resistance for each test point.

Test equipment:

  1. 100V DC Power Supply.

  2. Voltmenter. (V)

  3. Currentmeter (A)

V


R1







Earth Connecting



Figure 4 Insulation resistance test configuration

AC power line

100V


DC Power

Supply

EUT

T

T1

R


1kΩ

A

5.1.6 Characteristics of TE for ringing signals


5.1.6.1 Response to ringing signal

Requirement: If a ring detect function is provided and enabled, the TE shall be able to response to ringing signals of 45 V rms at 20 Hz with a cadence of 1 sec. on and 2 sec. off superimposed on a 48 VDC feeding voltage and series 5 kΩresistor.

Purpose: To verify the TE has to provide a minimum ringing response characters.

Test method:



  1. Response to ringing signal Test Configuration as Fig.5.

  2. Response to ringing signal test method:

  1. The EUT should be at on-hook state.

  2. Set AC signal generator to 20Hz and adjust the ring signal level to 45Vrms.

  3. Check to see that the EUT provides an audible acoustic output or other response states.


5 kΩ

EUT






Ring signal Generator

48VDC

Figure 5 Response to ringing signal test configuration

Test equipment:


  1. DC power supply.

  2. Ring signal generator : Frequency generator + Ringing amplifier



5.1.6.2 Ringing Impedance


Requirement: Requirement: The ringing impedancce of the terminal equipment at ringing signal 20Hz, 75Vrms shall not be less than 5kΩ and capacitance shall be less than 3.0μF.

Purpose: It is assured by requiring the TE to present a impedance to ringing signals that is sufficiently high.

Test method:


  1. Ringing Impedance Test Configuration as Fig.6.

  2. Ringing Impedance test method:

  1. The EUT should be at on-hook state.

  2. Set AC signal generator to 20Hz and adjust the signal level until the reading of V1 in EUT is 75Vrms.

  3. Measure the AC voltage, V2.

  4. Calculated the ringing impedance of the EUT. Z = V1  V2  1000.

  5. Digital storage oscilloscope monitor and record the waveform of V1 and V2.

  6. Calculate the phase angleθof impedance and the capacitance of EUT.

  1. θ= △t 50ms  360

  2. C = 1 /ω Z  sin whereω= 2π f

θ : phase angle of impedance

△t : time different of V1 and V2


EUT







Ring signal Generator

48VDC

1 kΩ

V2

V1

Digital Storage Oscilloscope

Ch1 GND Ch2


Figure 6 Ringing Impedance Test Configuration


Test equipment:



  1. Digital storage oscilloscoge.

  2. Ring signal generator : Frequency generator + Ringing amplifier

  3. DC power Supply.

  4. AC Voltmeter(V1 and V2).



5.1.6.3 On-hook AC impedance


Requirement: While EUT is at on-hook state loaded with 3Vrms, 200Hz ~ 3200Hz AC signal on the

telephone line, the AC impedance shall be in the acceptable region of Figure 7.

Purpose: To prevent the interference to other TE connecting with in parallel.

Test method:



  1. On-hook AC impedance test configuration as Fig.8.

2. On-hook AC impedance test method:

  1. EUT set on-hook state.

  2. Set the AC signal generator to 200 Hz and adjust the output level to let V2 be 3 Vrms reading.

  3. Measure and record the V1.

  4. Calculate the AC impedance Z = V2  V1 x 10 kΩ.

  5. Vary the AC signal generator slowly from 200 Hz to 3200 Hz, keeping V2 at 3 Vrms reading.

  6. Repeat step (3) to (4) .



200

300

500

1000

2000

50

100

(200, 30)

(697, 100)

(1633, 100)

(3200, 60)

Unacceptable Area


Acceptable Area

Fig.7 AC Impedance for On-hook Mode

AC Impedance (kΩ)

3200(Hz)

AC Signal

Generator


EUT


10kΩ

V2

V1

Figure 8 On-hook AC impedance test configuration

Test equipment:

1. AC Signal Generator.

2. AC Voltmeter  2.



5.1.7 Off-hook DC resistance


Requirement: The DC voltage to loop current characteristics of the TE during the any operating function of off-hook state shall appear on the acceptable region shown in Fig.9.

Purpose: To verify that the steady state DC loop characteristics. The test only applies to TE which are capable of reaching the loop state.

Test method:


    1. Off-hook DC resistance Test Configuration as Fig.10.

    2. Off-hook DC resistance test method:


A

VR

48VDC







EUT



V

Figure 10 Off-hook DC resistance Test Configuration




  1. The EUT should be at off-hook state.

  2. Adjust the VR to let A be 10mA and 20mA readings separately, then record the corresponding DC voltage and map the point into Fig.9. Each current reading shall stay at least 5 seconds interval.

(3) Adjust the VR to let V be 10.6V reading, then record the DC current and map the point into Fig.9.

  1. Repeat step (2) to (3) for each operating functions states of EUT.

Test equipment:

1. DC Power Supply.



  1. DC Voltmeter.

  2. DC Currentmeter.

  3. Variable Resistor.



5.1.8 Sending level limitations of signals


Requirement: All the output level s of internal signals transmitted from TE except the DTMF, which will be sent to the public switched telephone network, should follow:

  1. The mean sending level in the frequency range 200 Hz to 4000 Hz over a one-minute period shall not be greater than –10dBm when the TE interface is terminated with the reference impedance 600 ohms. Output level shall be not adjustable to over this limit range by the user. This requirement does not apply to DTMF signals.

  2. The mean sending level in the frequency range 4kHz to 8kHz over a one-minute period shall not be greater than –20dBm when the TE interface is terminated with the reference impedance 600 ohms.

  3. The mean sending level in the frequency range 8kHz to 12kHz over a one-minute period shall not be greater than –40dBm when the TE interface is terminated with the reference impedance 600 ohms.

  4. The mean sending level on the 4kHz bandwidth over the frequency range 12kHz to 40kHz over a one-minute period shall not be greater than –60dBm when the TE interface is terminated with the reference impedance 600 ohms.

The leased line equipment have to meet this requirement.

Purpose: To verify that the voice band signal power and out-band noise from internal sources, other than DTMF, which will be sent to public switched telephone network are properly limited.

Test method:


  1. Sending level limitations of signals Test Configuration as Fig.11.

EUT

Loop Simulator

Bandpass Fielter


AC RMS Voltmeter


R



Figure 11 Sending level limitations of signals Test Configuration





  1. Sending level limitations of signals test method:

  1. Place the EUT in the desired state and transmit a signal at maximum power.

  2. Set band-pass filter in 200Hz to 4000Hz,

  3. Measure and record the maximum averaged output signal power level in dBm.

  4. Band-pass filter to bandwidth 4kHz~8kHz/ 8kHz~12kHz…… /36kHz~40kHz.

  5. Measure and record the maximum averaged output signal power level in dBm for each bandwidth.

  6. Repeat step (2) to step (5) for other internal output signals.

Test equipment:

  1. Loop Simulator.

  2. Bandpass Fielter.

  3. AC RMS Voltmeter.

  4. R : Reference Load of 600Ω



5.1.9 Transverse balance limitations


Requirement: TE are at on-hook, off-hook and tip-ring reverse states test, the minimum transverse balance requirements as TABLE 2.

State

Frequency

Balance

Off-hook

200Hz≦f≦4000Hz

40dB

On-hook

200Hz≦f<1000Hz

60dB

On-hook

1000Hz≦f≦4000Hz

40dB

Technical description: The transverse balance coefficient is expressed as:

Transverse Balance m-1 = 20 log10 Vm / V1

V1: is the longitudinal voltage produced across a longitudinal termination R2(500Ω) Vm (0.775V): is the metallic voltage across the tip and ring interface of the input port when a voltage at frequency band 200Hz to 4000 Hz is applied from a balance source with a metallic impedance R0 (a corrective circuit) . The source voltage should be set such that Vm = 0.775 Volts when a termination of R0 is substituted for TE.

Purpose: To ensure that the impedance unbalance about earth, expressed as output signal balance.

Test method:


  1. Test Configuration of Transverse balance limitations is as Fig.12.

  2. Transverse balance limitation test method:

  1. Set the AC signal generator to 200 Hz.

  2. Connect R0 ( corrective circuit) to the test circuit Fig.12.

  3. Adjust the output voltage (Vm) of AC signal generator to the frequency selective voltmeter, which acrosses R0 , to be setted at 10Hz bandwidth and 0.775V.

  4. Connect the frequency selective voltmeter to across the R2 and test Vl.

  5. Adjust variable capacitors C3 and C4 until the minimum signal level of Vl is obtained. (The result of this balance calibration must be at least 20dB greater than the balance requirement for the EUT at the frequency.)

  6. Replace R0 with EUT and set EUT at on-hook.

  7. Measure the metallic reference voltage (Vm) and the transverse voltage (V1).

  8. Calculate the balance using the following formula :

Transverse Balance = 20 log Vm / V1

  1. Reverse the tip and ring connections of the EUT and repeat step (7) to (9). The lesser of the two results is the transverse balance of the EUT at 200 Hz.

  2. Repeat step (2) to (10) for at least each of the following frequencies : 500, 1000, 2000, 3000 and 4000 Hz.

  3. Repeat step (1) to (10) for each operational states.



EUT



Earth

Loop Simulator



AC Signal Generator

R1







C1

C2

R2

Vl

C3

C4



Vm

R0


Tip

Ring

T1

200 ~4000Hz

Earth metal

Figure 12 Test Configuration of Transverse balance limitations

300 kΩ

300Ω

300Ω

350Ω

Tip

Ring

Figure 13 Ro Corrective circuit

Test equipment:



  1. AC Signal Generator.(ZOSC must be less or equal to 600Ω)

  2. Loop Simulator.

  3. R0:Corrective circuit as Figure 13.

  4. R2:500Ωfor longitudinal resistor

  5. T1:600Ω:600Ωsplit audio transformer

  6. C1/C2:8mF±0.1%, 400V

  7. C3/C4:100 ~ 500pF adjustable trimmer capacitors

  8. R1:ZOSC+R1=600Ω



5.1.10 Return loss


Requirement: For all operational states of TE at 0 KM simulative loop, the return loss of TE shall meet the following requirement:

  1. The return loss shall be greater than an echo return loss (ERL) of 8dB over a frequency band of 500 Hz to 2500 Hz when measured against to 600Ω.

  2. The return loss in the frequency band 200 Hz to 3200 Hz shall be greater than 6dB when measured against to 600Ω.

Purpose: To assured by requiring the TE to present a impedance which allows proper functioning of call control and to maintain stability in the PSTN.

Test method:



  1. Return loss Test Configuration as Fig.14.

  2. Return loss test method:

  1. Set the EUT not to transmit any signals in the off-hook state.

  2. Put EUT in the off-hook state with the simulative loop be set at 0 KM.

(3) Vary the oscillator frequency from 200 Hz to 3200 Hz and record the minimum

value of return loss and frequency at which it occurs.

(4 )Set EUT to be at each off-hook operational states, then repeat step (3).

Oscillator


EUT

Loop Simulator

600Ω

Return Loss Tester



C





Figure 14 Return loss Test Configuration


Test equipment:



  1. Loop Simulator.

  2. Return Loss Tester.

  3. Oscillator.

  4. C: 125μF±10%



5.1.11 Pulse dialing


Requirement: TE shall send normal pulse when TE be dialed the specifications are as follows.

(1) Pulse speed:10±1 P.P.S.

(2) Make / Brake ratio:33±3%.

(3) Minimum Inter-digit time:600msec.

Pulse dialing trigger current: High = 18 mA, Low = 6mA.

Purpose: To assure effective pulse dialing of TE to PSTN.

Test method:

1.Pulse dialing test configuration as Fig.15.


Adjustable artificial line

EUT

Loop Simulator

Storage


Type

Oscilloscope








Figure 15 Pulse dialing test configuration

2. Pulse dialing test method:


    1. Set artificial line at 0 kM.

    2. Let TE send out Pulse Dial signals.

    3. Measure and record the DC Voltage of Pulse Dial signals.

    4. Set artificial line at 5 kM, repeat steps (2) to (3).

    5. Use the below fomula to calculate the average pulse speed, M/B ratio and minimum interdigital time.






T1 & T2 : Time at low trigger current

T3 & T4 : Time at high trigger current

Make interval : begins≧T3 ends≦T4

Brake interval : begins≦T1 ends≧T2

Rise time : begins≧T2 ends≧T3

Fall time : begins≦T3 ends≦T1

Period : begins≧T4 ends≧T3


  • P.P.S. = 1 ÷Period.

  • Make / Brake ratio = Make interval ÷Period x 100%.

  • Minimum Interdigital Interval Pause:

The minimum pause time between any two pulse dial digits.

Test equipment:

1.Adjustable artificial line.

2.Loop Simulator.

3.Storage Type Oscilloscope.

5.1.12 Dual tone multiple frequency (DTMF) dialing

5.1.12.1 Frequency combination


Requirement: The TE shall use DTMF signaling characters according to table 3. The tolerances on the frequencies for the characters supported shall be ±1.5 % when artificial line at 0 kM and 5 kM.

Purpose: To verify whether the TE sends appropriate DTMF signal frequency combination to PSTN. The allowed combinations are listed in the table3.


Table 3 : Frequency of DTMF signals

LGP(Hz)

HGP (Hz)

1209

1336

1477

1633

697

1

2

3

A

770

4

5

6

B

852

7

8

9

C

941

*

0

#

D

Test method:

  1. Frequency combination test configuration as Fig.16.

  2. Frequency combination test method:

  1. The artificial line set to 0 KM.

  2. Let the EUT transmit DTMF signal "1"to line.

  3. Measure and record the frequency of DTMF signals.

  4. Calculate the frequency deviation.

  5. Repeat for each of the other dialer number that the EUT is equipped to generate. Repeat step (3) to (4).

  6. Set artificial line to 5 KM, Repeat step (2) to (5).

Spectrum Analyzer

EUT

Loop Simulator




Adjustable artificial line

Figure 16 Frequency combination test configuration


Test equipment:



  1. Adjustable Artificial line.

  2. Loop Simulator.

  3. Spectrum Analyzer.



5.1.12.2 Signaling level


Requirement:

  1. The level of any tone in the DTMF high frequency group shall be –6 ±2dBm and the level of any tone in the low frequency group shall be –8 ±2dBm when the TE interface is terminated with the reference impedance 600 ohms and artificial line at 0 KM.

  2. The level of any tone in the DTMF high or low frequency group shall be ≧-21dBm when the TE interface is terminated with the reference impedance 600 ohms and artificial line at 5 KM.

Purpose: To check whether the TE sends appropriate DTMF signals.

Test method:



  1. Signaling level test configuration as Fig.17.

  2. Signaling level test method:

  1. The artificial line set to 0 KM.

  2. Let the EUT transmit DTMF signal "1"to line.

  3. Measure and record the frequency of DTMF signals power level.

  4. Repeat for each of the other dialer number that the EUT is equipped to generate. Repeat step (3).

  5. Set artificial line to 5 KM, Repeat step (2) to (4).


Adjustable artificial line

Spectrum Analyzer


R

EUT

Loop Simulator


Figure 17 Signaling level test configuration

Test equipment:


  1. Adjustable Artificial line.

  2. Loop Simulator.

  3. Spectrum Analyzer.

  4. R: 600Ω Reference Load.



5.1.12.3 Signaling level difference


Requirement: During sending of any DTMF frequency combination, the level of the tone in the high frequency group shall be 0 to 3 dB high than the level of the tone in the low frequency group when artificial line at 0KM.

Purpose: To check whether the TE sends appropriate DTMF signals.

Test method:


  1. Signaling level difference test configuration as Fig.17.

2. Signaling level test method:

  1. The artificial line set to 0 KM.

  2. The EUT set in the off-hook stated, transmitting DTMF signal to line.

  3. Send dialer no. 1 signal, measure and record the frequency of DTMF signals power level.

  4. Calculate the signal level difference.

  5. Repeat for each of the other dialer number that the EUT is equipped to generate. Repeat step (2) to (4).

Test equipment:

  1. Adjustable Artificial line.

  2. Loop Simulator.

  3. Spectrum Analyzer.



5.1.12.4 Tone duration


Requirement: The TE shall provide a setting whereby the duration for which any individual DTMF tone combination sent is not less than 40 ms. This requirement applies only to a TE with an automatic dialing function. It applies when the TE is in automatic dialing mode.

Purpose: To check whether the TE sends DTMF signals of the appropriate duration.

Test method:


  1. Tone duration test configuration as Fig.18.

  2. Tone duration test method:

  1. The artificial line set to 0 KM.

  2. The EUT set in the off-hook stated and automatic dialing mode.

  3. Transmitting DTMF signal to line.

  4. Measure and record the all DTMF signal.

  5. Calculate and record the minimum tone duration.

  6. Adjust the artificial line to 5KM, Repeat step(2) to (5).


Adjustable artificial line

EUT

Loop Simulator

Storage


Type

Oscilloscope






Figure 18 Tone duration test configuration


Test equipment:

  1. Adjustable Artificial line.

  2. Loop Simulator.

  3. Storage Type Oscilloscope.



5.1.12.5 Pause duration


Requirement: The TE shall provide a setting whereby the duration of the pause between any

individual DTMF tone combination is not less than 50 ms. This requirement applies only to a TE with an automatic dialing function.Purpose: To check whether the TE sends DTMF signals of the appropriate duration. This requirement applies only to a TE with an automatic dialing function. It applies when the TE is in automatic dialing mode.

Purpose: To check whether the TE sends DTMF signals of the appropriate duration.

Test method:



  1. Pause duration test configuration as Fig.18.

  2. Pause duration test method:

  1. The artificial line set to 0 KM.

  2. The EUT set in the off-hook stated and automatic dialing mode.

  3. Transmitting DTMF signal to line.

  4. Measure and record the all DTMF signal.

  5. Calculate and record the minimum pause duration between any individual DTMF signal.

  6. Adjust the artificial line to 0 KM and repeat step (2) to (5).

Test equipment:

  1. Adjustable Artificial line.

  2. Loop Simulator.

  3. Storage Type Digital Oscilloscope.



5.1.13 Series equipment

5.1.13.1 DC voltage drop of series equipment


Requirement: The DC voltage drop across the line connections shall be less than 3V with loop current at 30mA and shall be less than 6V with loop current at 60mA.

Purpose: Series equipment which is connected and operates with another TE which is in the off-hook condition, or which remain in the circuit at all times.

Test method:

1. DC voltages drop of series equipment test configuration as Fig.19.

2. DC voltage drop of series equipment test method:


  1. Adjust variable resistor to give a loop current 30mA.

  2. Measure and record DC voltmeter V1.

  3. EUT set to be at on-hook state and connect to the configuration as fig.19.

  4. Measure and record DC voltmeter V2.

  5. Calculate DC voltage drop = V2 – V1.

  6. Adjust variable resistor to give a loop current 60mA and repeat step (2) to (5).

Test equipment:

  1. Loop Simulator.

  2. Currentmeter A.

  3. DC Voltmeter V1 and V2.

  4. VR:variable resistor



600Ω








A

V

VR

Loop Simulator



Figure 19 DC voltages drop of series equipment test configuration


EUT


5.1.13.2 Insertion loss of series equipment


Requirement: The Insertion Loss of Series Equipment shall be less than 1.5 dB at frequency 1500 Hz when test with signal level of – 10dBV and reference load 600Ω.

Purpose: Series equipment which is connected and operates with another TE which is in the off-hook condition, or which remain in the circuit at all times.

Test method:


  1. Insertion loss of series equipment test configuration as Fig.20.

  2. Insertion loss of series equipment test method

  1. Set the frequency generator to 1500 Hz and adjust to an output level of –10dBV as measured by the AC voltmeter across 600 ohms resistor.

  2. EUT set to on-hook state and connect EUT to the test circuit Fig.20.

  3. Measure and record the AC voltmeter V (dBV).

  4. Calculate insertion loss = –10dBV – V.

EUT


C: 2μF±10%

AC


Voltmeter


Loop Simulator


Signal Generator

Zs = 600

600Ω


Figure 20 Insertion loss of series equipment test configuration


Test equipment:



  1. Signal Genterator.

  2. Loop Simulator.

  3. AC Voltmeter.
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