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 interfaceThis British Standard, having been prepared under the direction of the Telecommunications Sector Assembly, was published under the authority of the DISC Board and comes into effect on 15
3、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 33035 4 BS 7940:1999 Amendments issued since publication Amd. No. Date Comments Committees responsible for this British Standard The preparat
4、ion of this British Standard was entrusted to Technical Committee TCT/2, Analogue telecommunications networks, upon which the following bodies were represented: British Approvals Board for Telecommunications British Association of the Hard of Hearing British Micro Computer Manufacturers Group (BMMG)
5、 British Telecommunications plc Cable they are not intended as a substitute for the published network characterizations of the actual PSTNs provided by UK Public Network Operators The requirements in this standard are not intended to be used for regulatory purposes. Reasons for the inclusion of each
6、 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 which other standards apply. 1 Scope This British Standard is applicable to apparatus incorporating an interface for the connection of termi
7、nal 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, loop clearing) and specifies the performance requirements of the interface so as to make it appear to the attached terminal equipment that i
8、s 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 provided PBX signalling protocols of either loop calling-guarded clearing, loop calling-disconnect clearing, or earth calling. This standa
9、rd 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 the internal connection between the terminal support interface and the NCP uses radio communication means such as CT2 and PCN. This stan
10、dard 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 100V. NOTE 2 Cable with a loop resistance of 100V is equivalent to approximately 500 m of cable with 0.5 mm diameter copper conductors.
11、The electrical conditions specified for the apparatus at the terminal support interface are sufficient to ensure satisfactory operation of some or all of the following functions of approved terminal equipment: a) call control; b) transmission; c) signalling; d) ringing. 2 Normative references The fo
12、llowing normative documents contain provisions which, through reference in this text, constitute provisions of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication
13、 referred to applies. BS 6312-1:1994, Connectors for analogue telecommunications interface Part 1: Specification for plugs. BS 6305:1992, Specification for general requirements for apparatus for connection to public switched telephone networks run by certain public telecommunications operators. ITU-
14、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 following terms and definitions apply. 3.1 Abbreviated terms ALASS analogue local access signalling services NOTE For information on ALASS
15、 see annex C. CAI common air interface CT2 second generation cordless telephone DTMF dual tone multi frequency LD loop disconnect NCP network connection point NTP network termination point PCN personal communication network PSTN public switched telephone network PTRP port test reference point TE ter
16、minal equipment TSI terminal support interface2 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
17、apparatus which when providing a transmission 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
18、apparatus internal transmission path 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 r
19、eferred to a point of zero level 3.2.8 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
20、 TSI by the apparatus in response to 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
21、to below 1 mA for a period normally 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 sta
22、te optional electrical state into which 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 transmissi
23、on times in both directions of transmission 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 ter
24、minated, the PSTN standard interface 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
25、 NCP and the interface 3.2.17 on-line 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 transmissi
26、on 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 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
27、apparatus to and from which the various 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 i
28、ndication that a terminal is attempting to establish a connection BSI 10-1999 3 BS 7940:1999 3.2.21 suppliers declaration a declaration based upon evidence held by the supplier that the relevant requirements are met. Such evidence shall consist of actual test information or other substantiating mate
29、rial 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 which supports certain terminal equipment functions 3.2.23 transparent signalling facility whereby netw
30、ork 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 requirements 4.1 Terminal support interface 4.1.1 Mechanical requirements The analogue terminal support in
31、terface (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. 4.1.2 Connection arrangements 4.1.2.1 Loop presentation Connections equivalent to the A- and B- wires
32、 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 1.80mF 0.18mF shall be connected between terminals 4 and 5 of the TSI socket. Conformity shall be checked by measurement.
33、 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 information provided by the supplier in accordance with clause 14. Table 1 Apparatus types Apparatus type Appara
34、tus internal transmission path Network connection A 2-wire 2-wire analogue B 4-wire a 2-wire analogue C 4-wire 4-wire digital a The internal 4-wire transmission path may be analogue or digital. NOTE The possible states of the apparatus, and the transitions between states are shown in Figure 2. An ex
35、ample of a PTRP is shown in Figure 3.4 BSI 10-1999 BS 7940:1999 Figure 1 Apparatus types BSI 10-1999 5 BS 7940:1999 Figure 2 Apparatus state transition diagram Figure 3 PTRP example 5 D.C. feed conditions 5.1 Loop current, on-line state When a resistor with a value in the range 0V to 460V is connect
36、ed between terminals 2 and 5 of the TSI, a d.c. current within the range (32 7) 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 during the on-line and off-line idle states shall be such that terminal
37、 5 (the B-wire) is normally negative with respect to terminal 2 (the A-wire). Conformity shall be determined by the test of A.5.2.1.6 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
38、exceed 70 V. Conformity shall be determined by the test of A.5.2.2.1. 5.2.2.2 Minimum voltage 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
39、 A.5.2.2.2. 5.2.3 Polarity reversal For apparatus types A and B, any polarity reversal applied 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
40、 not seize condition When a resistor with a value such as to cause a loop current not greater 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 seiz
41、e condition 6.2.1 General When a resistor with a value not exceeding 5.65 kV is connected at 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 conf
42、orm to the requirements of 6.2.2 and apparatus type C shall conform to the requirements of 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 seiz
43、e condition, it is recommended that a “connection not admitted” supervisory tone is presented 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 an
44、y voice band supervisory signals applied at the network connection point to the terminal equipment. 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
45、provide a transmission path between NCP and the TSI so as to present any voice band supervisory 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
46、TE When the load presented by terminal equipment connected at terminals 2 and 5 of the TSI is 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 a
47、s 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 o
48、n the nature of the disconnect request message to enable testing to be performed. Conformity shall be determined by the test of A.7.1. 7.2 Clear signal received from the network 7.2.1 2-wire network connection When type A or type B apparatus receives a PSTN end-of-call signal (K-break) at the NCP, i
49、t shall remove the transmission path between the NCP and the TSI and shall apply a disconnect signal at the TSI. Conformity shall be determined by the test of A.7.2.1. 7.2.2 4-wire network connection When type C apparatus receives a disconnect clear message from the network, it shall terminate the transmission path between the NCP and the TSI, and shall apply a disconnect signal to the terminal equipment. The supplier shall provide information on the nature of the network disconnect message to permit testing to be performed. NOTE The disconnect clear message may also b
