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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7940:1999 ICS 33.040.3
2、5 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Analogue PSTN terminal support interface Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:39:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared unde
3、r the direction of the Telecommunications Sector Assembly, was published under the authority of the DISC Board and comes into effect on 15 October 1999 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference TCT/2 Draft for comment 98/632009 DC ISBN 0 580 33
4、035 4 BS 7940:1999 Amendments issued since publication Amd. No.DateComments Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee TCT/2, Analogue telecommunications networks, upon which the following bodies were represented: Br
5、itish Approvals Board for Telecommunications British Association of the Hard of Hearing British Micro Computer Manufacturers Group (BMMG) British Telecommunications plc Cable they are not intended as a substitute for the published network characterizations of the actual PSTNs provided by UK Public N
6、etwork Operators The requirements in this standard are not intended to be used for regulatory purposes. Reasons for the inclusion of each requirement defined in the main body of this standard are given in annex B. Apparatus covered by this standard may additionally provide other types of port to whi
7、ch other standards apply. 1 Scope This British Standard is applicable to apparatus incorporating an interface for the connection of terminal equipment intended for connection to a single 2-wire analogue line interface of the PSTN (known commonly as a Direct Exchange Line, and using loop calling, loo
8、p clearing) and specifies the performance requirements of the interface so as to make it appear to the attached terminal equipment that is inter-working with a single 2-wire analogue interface of the PSTN. NOTE 1 A single 2-wire analogue interface of the PSTN is one which does not use the commonly p
9、rovided PBX signalling protocols of either loop calling-guarded clearing, loop calling-disconnect clearing, or earth calling. This standard is applicable to apparatus where the loop current provided to the terminal equipment is not directly derived from a PSTN connection and includes apparatus where
10、 the internal connection between the terminal support interface and the NCP uses radio communication means such as CT2 and PCN. This standard is applicable to apparatus where any terminal equipment connected to the terminal support interface is connected via a cable with a maximum loop resistance of
11、 100 V. NOTE 2 Cable with a loop resistance of 100 V is equivalent to approximately 500 m of cable with 0.5 mm diameter copper conductors. The electrical conditions specified for the apparatus at the terminal support interface are sufficient to ensure satisfactory operation of some or all of the fol
12、lowing functions of approved terminal equipment: a) call control; b) transmission; c) signalling; d) ringing. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this British Standard. For dated references, subse
13、quent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication referred to applies. BS 6312-1:1994, Connectors for analogue telecommunications interface Part 1: Specification for plugs. BS 6305:1992, Specification for gener
14、al requirements for apparatus for connection to public switched telephone networks run by certain public telecommunications operators. ITU-T Recommendation P.53, Psophometer (apparatus for the objective measurement of circuit noise)1). 3 Terms and definitions For the purposes of this standard, the f
15、ollowing terms and definitions apply. 3.1 Abbreviated terms ALASSanalogue local access signalling services NOTE For information on ALASS see annex C. CAIcommon air interface CT2second generation cordless telephone DTMFdual tone multi frequency LDloop disconnect NCPnetwork connection point NTPnetwork
16、 termination point PCNpersonal communication network PSTNpublic switched telephone network PTRPport test reference point TEterminal equipment TSIterminal support interface Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:39:27 GMT+00:00 2006, Uncontrolled Copy
17、, (c) BSI 2 BSI 10-1999 BS 7940:1999 3.2 Definitions 3.2.1 2-wire apparatus apparatus which when providing a transmission path between the interface port and the network connection point uses the same path for each direction of transmission 3.2.2 4-wire apparatus apparatus which when providing a tra
18、nsmission path between the interface port and the network connection point uses separate paths for each direction of transmission 3.2.3 answer signal indication that a terminal wishes to answer an incoming call 3.2.4 apparatus type classification dependent on the apparatus internal transmission path
19、 and network connection NOTE Types are defined in Table 1. 3.2.5 clear signal indication that a terminal or the network is attempting to release a connection 3.2.6 dBV the absolute voltage expressed as dB relative to 1 V 3.2.7 dBm0 the absolute power level in dB referred to a point of zero level 3.2
20、.8 dBm0p the absolute psophometric power level in dB referred to a point of zero level 3.2.9 dBmp the absolute psophometric power level expressed as dB relative to 1 mW 3.2.10 disconnect signal break of duration 90 ms to 110 ms in the loop current presented at the TSI by the apparatus in response to
21、 an end-of-call signal received at the NCP 3.2.11 end-of-call signal signal usually provided at the called analogue NTP by the network to indicate when a calling TE has resumed the quiescent state NOTE 1 The signal consists of a reduction in the PSTN loop current to below 1 mA for a period normally
22、in the range 90 ms to 130 ms. There are some NTPs in existence which provide break periods in the range 20 ms to 128 ms, but 90 ms to 110 ms is the preferred range for new installations. NOTE 2 This signal is also known as a K-break. 3.2.12 off-line signalling state optional electrical state into wh
23、ich terminal equipment (TE), when connected to the network, is placed such that it is capable of sending or receiving speechband signalling without entering the on-line transmission state 3.2.13 mean one-way transmission time half the sum of the one-way transmission times in both directions of trans
24、mission between the interface port and the network connection point 3.2.14 network connection point point provided by the apparatus intended for connection to a network termination point 3.2.15 network termination point point where the local subscriber line is terminated, the PSTN standard interface
25、 is presented and the TE is connected 3.2.16 off-line idle state condition of the apparatus where it has no seize signal applied at the terminal support interface, it has applied a release condition at the NTP and where no transmission path is provided between the NCP and the interface 3.2.17 on-lin
26、e signalling state condition of the apparatus where it has a seize signal applied at the interface, it has applied a seize signal to the NTP and is capable of transmitting to the NTP any network address signalling applied at the interface 3.2.18 on-line transmission state condition of the apparatus
27、where it has a seize signal applied at the interface, it has applied a seize signal to the NTP, and where it provides a voice band transmission path between the NCP and the interface 3.2.19 port test reference point (PTRP) point on the transmission path of 4-wire apparatus to and from which the vari
28、ous transmission parameters may be summed to give the overall transmission performance NOTE 1 For apparatus employing radio transmission means for the transmission path, the PTRP is assumed to be at the appropriate common air interface (CAI). 3.2.20 seize signal indication that a terminal is attempt
29、ing to establish a connection Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:39:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 10-19993 BS 7940:1999 3.2.21 suppliers declaration a declaration based upon evidence held by the supplier that the relevant requ
30、irements are met. Such evidence shall consist of actual test information or other substantiating material relating to the design of the apparatus 3.2.22 terminal support interface port provided by the apparatus for connection of terminal equipment intended for connection to the analogue PSTN, and wh
31、ich supports certain terminal equipment functions 3.2.23 transparent signalling facility whereby network address information and supervisory signals are conveyed between the terminal support interface and the PSTN connection point without regeneration within the apparatus 4 Physical connection requi
32、rements 4.1 Terminal support interface 4.1.1 Mechanical requirements The analogue terminal support interface (TSI) shall be presented at a socket compatible with a plug conforming to BS 6312-1. Conformity shall be checked by inspection. NOTE Details of a suitable connector are given in BS 6312-2-1.
33、4.1.2 Connection arrangements 4.1.2.1 Loop presentation Connections equivalent to the A- and B- wires of the 2-wire analogue PSTN connection shall be presented at terminals 2 and 5 of the TSI. Conformity is checked by the test of clause 6. 4.1.2.2 Shunt connection A capacitor of 1.80 mF0.18 mF shall
34、 be connected between terminals 4 and 5 of the TSI socket. Conformity shall be checked by measurement. 4.2 Network connections The supplier shall declare which type of apparatus, in accordance with Table 1 and shown in Figure 1, is provided. Conformity shall be checked by reference to the informatio
35、n provided by the supplier in accordance with clause 14. Table 1 Apparatus types Apparatus typeApparatus internal transmission path Network connection A2-wire2-wire analogue B4-wirea2-wire analogue C4-wire4-wire digital aThe internal 4-wire transmission path may be analogue or digital. NOTE The poss
36、ible states of the apparatus, and the transitions between states are shown in Figure 2. An example of a PTRP is shown in Figure 3. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:39:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 BSI 10-1999 BS 7940:1999 Figu
37、re 1 Apparatus types Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:39:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 10-19995 BS 7940:1999 Figure 2 Apparatus state transition diagram Figure 3 PTRP example 5 D.C. feed conditions 5.1 Loop current, on-line
38、state When a resistor with a value in the range 0 V to 460 V is connected between terminals 2 and 5 of the TSI, a d.c. current within the range (327) mA shall flow. Conformity shall be determined by the test of A.5.1. 5.2 Voltage 5.2.1 Polarity The polarity of the d.c. voltage presented at the TSI d
39、uring the on-line and off-line idle states shall be such that terminal 5 (the B-wire) is normally negative with respect to terminal 2 (the A-wire). Conformity shall be determined by the test of A.5.2.1. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:39:27 GM
40、T+00:00 2006, Uncontrolled Copy, (c) BSI 6 BSI 10-1999 BS 7940:1999 5.2.2 Off-line idle state 5.2.2.1 Maximum emf The maximum open circuit d.c. voltage presented between terminals 2 and 5 of the TSI shall not exceed 70 V. Conformity shall be determined by the test of A.5.2.2.1. 5.2.2.2 Minimum volta
41、ge When a resistor of 100 kV is connected between terminals 2 and 5 of the interface, the continuous d.c. voltage appearing at the TSI shall be not less than 32 V. Conformity shall be determined by the test of A.5.2.2.2. 5.2.3 Polarity reversal For apparatus types A and B, any polarity reversal appl
42、ied at the NCP during the on-line and off-line idle states shall cause a polarity reversal to be applied at the TSI within 100 ms. Conformity shall be determined by the test of A.5.2.3. 6 Seize signal 6.1 Must not seize condition When a resistor with a value such as to cause a loop current not great
43、er than 2.5 mA d.c. to flow is connected at terminals 2 and 5 of the interface, it shall not be recognized by the apparatus as a seize signal. Conformity shall be determined by the test of A.6.1. 6.2 Must seize condition 6.2.1 General When a resistor with a value not exceeding 5.65 kV is connected a
44、t terminals 2 and 5 of the TSI, it shall cause a current not less than 4.0 mA d.c. to flow, which shall be correctly accepted by the apparatus as a seize signal. In addition, apparatus types A and B shall conform to the requirements of 6.2.2 and apparatus type C shall conform to the requirements of
45、6.2.3. Conformity shall be determined by the test of A.6.2. NOTE If, due to abnormal network or external conditions, the apparatus is unable to meet the requirements 6.2.2 and 6.2.3 in response to a valid seize condition, it is recommended that a connection not admitted supervisory tone is presented
46、 at the TSI. 6.2.2 2-wire network connection The apparatus shall present a loop condition at the NCP and shall provide a transmission path between the network connection point and the TSI so as to present any voice band supervisory signals applied at the network connection point to the terminal equi
47、pment. 6.2.3 4-wire network connection The apparatus shall apply an establish signal to the network connection point and shall either present internally generated dial tone to the TSI within 0.5 s, or shall provide a transmission path between NCP and the TSI so as to present any voice band superviso
48、ry signals applied at the NCP to the TSI. The supplier shall provide information on the nature of the network establish signal to enable testing to be performed. 7 Clear signal 7.1 Clear signal generated by TE When the load presented by terminal equipment connected at terminals 2 and 5 of the TSI is
49、 such as to reduce the loop current to less than 1.0 mA for a period: a) less than 150 ms, the apparatus shall not accept this as a clear signal; and b) greater than 500 ms, the apparatus shall accept this as a clear signal and shall terminate the transmission path between the NCP and the TSI, and shall either release the loop condition applied at the NCP for apparatus types A and B, or shall transmit a disconnect request message to the NTP for apparatus type C. The supplier shall provide information on the nature of the disconnect request message to enable testing to b
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