1、CEPT T/CS*4b-O3*E 2326434 0004851 2 (3 TCs46-03E Page 1 Recommendation T/CS 46-03 (Innsbruck 1981, revised at Nice 1985) SIGNALLING SYSTEM FOR PUSH-BUTTON TELEPHONES COMBINING BASIC MULTIFREQUENCY SIGNALLING WITH DIRECT CURRENT SIGNALLING Recommendation proposed by Working Group T/WG 11 “Switching a
2、nd Signalling” (CS) Revised text of the Recommendation adopted by the “Telecommunications” Commission “The European Conference of Postal and Telecommunications Administrations, considering - that access to the services of the telephone network will be provided by telephone sets equipped with 12 or -
3、 that the use of these telephone sets and their signalling technique for a simple type of end-to-end data transmission - that the existing CCITT Recommendations on the subject do not yet assure the required standardisation; - that the Administrations are in favour of harmonising telecommunications e
4、quipment and systems which could lead to a reduction in development and manufacturing cost for those industries that provide equipment for several countries, 16 push-buttons as recommended in CCITT Recommendation Q. 11 i for multifrequency signalling; in the international as well as in national netw
5、orks requires standardisation of the technique to be used; O recommends to the members, the application of the signalling system for push-button telephones (including those of private automatic branch exchanges), conforming with the specifications set out below, when a method combining basic multifr
6、equency signalling with direct current signalling is used.” Edition of May 15, 1986 i CEPT T/CS*4b-O3*E 2326434 0004852 4 1. 1.1. 1.2. 1.2.1. 1.2.2. 1.2.3. TICS 48-03 E Page 3 PRINCIPLES AND CODING General This section deals with the general characteristics of the combined multifrequency and direct
7、current signalling system. The signalling frequencies used are in accordance with CCITT Recommendation Q.23 2, the line current during signal transmission being reduced from that under normal conversational conditions (accompanying direct current signal). Signal frequencies and codes Signal frequenc
8、ies The signal frequencies shall be selected from two separate groups within the speech band (300-3,400 Hz), a low group and a high group, each group providing four signalling frequencies. These frequencies shall be : - low group frequencies: 697, 770, 852 and 941 Hz; - high group frequencies: 1,209
9、, 1,336, 1,477 and 1,633 Hz. Signal format Each signal shall consist of two and only two of the signalling frequencies, one frequency from each of the low and high groups, accompanied by a decrease in line current. Both frequencies and the decreased line current shall be applied simultaneously to th
10、e line. Signal code The sixteen discrete signals shall be allocated as shown in Table 1 (T/CS 46-03) below. Table 1 (T/CS 46-03). Table I (T/CS 46-03) gives the full allocation of signal codes. The system may be utilized with only 10 discrete signals, in which case the signals designated *, #, A, B,
11、 C and D will not be used; or with 12 discrete signals, in which case the signals A, B, C and D will not be used. Note: The presentation in Table 1 (T/CS 46-03) corresponds to the actual lay-out of the push-buttons on the terminal equipment. The arrangements and designations of buttons are further s
12、pecified in Recommendation T/CS 34-01 3. Edition of May 15, 1986 CEPT T/CS*4b-O3*E 232b4L4 0004853 b TICS 46-03 E Page 4 2. 2.1. 2.1.1. 2.1.2. 2.1.3. 2.2. 2.3. 2.3.1. 2.3.2. 2.3.3. 2.3.3.1. 2.3.3.2. 2.3.4. PUSH-BUTTON SENDER Area of application and general This Section deals with the multifrequency
13、sender to be used in push-button telephones with accompanying direct current signal. The sender has basically been specified for signalling to the exchange. However, regard has also been taken of the possible use of push-button telephones for end-to-end data transmission when manual operation applie
14、s. The requirements stated in this Section apply to an unregulated generator, i.e. a generator in which the output levels are not controlled by the line current. Operational conditions The sender is expected to operate under varying environmental conditions. (a) A general purpose sender should opera
15、te in temperature controlled locations and partly temperature controlled locations, i.e. in normal living and working areas as well as entrances, staircases of buildings, factories and industrial plants, etc. The relevant climate conditions are described in Recommenda- tion T/TR 02-06 4. The sender
16、must meet the requirements within these conditions. (b) A wide temperature range sender should operate in open air as well as sites with heat trap, i.e. telephone booths and similar installations. The relevant climatic conditions are described in Recommen- dation T/TR 02-06 4, Figure 3. The wide tem
17、perature range sender must meet the requirements within these conditions. Output requirements Frequency tolerance The output frequencies shall be maintained within f i .5% of their nominal values. This tolerance shall also include the effect of different line impedances offered to the sender. Sendin
18、g level The sending levels with a load resistance of 600 ohms shall be for: option 1 - the high frequency group: - 9 dBm f2 dB, - the low frequency group: - 11 dBm f2 dB; option 2 - the high frequency group: - 6 dBm f2 dB, - the low frequency group: - 8 dBm f2 dB; with a restriction that the level o
19、f the higher frequency component of the compound signal shall be 2 above the level of the lower frequency component. Unwanted frequency components When a signal is output: (a) the total power level of all unwanted frequency components shall be at least 20 dB below the level of the low group frequenc
20、y component of the signal; (b) the level of any individual unwanted frequency component shall not exceed the following limits: in the frequency band 300-4,300 Hz: 33 dBm; - in the frequency band 4,300-28,000 Hz: -37 dBm at 4,300 Hz, then falling at 12 dB/octave until - in the frequency band 28-70 kH
21、z: -70 dBm; - in the frequency band 70-200 kHz: -80 dBm; - in the frequency band above 200 kHz: -70 dBm. 1 dB 28 kHz; When no signal is output, the level of any single frequency emitted from the sender to line shall not exceed -80 dBm. Risetime The level of each of the two frequency components of th
22、e multifrequency signal shall be be within 1 dB of the final value after 7 ms from the time that the line current starts to decrease. The direct current of the line shall decrease to the upper limit of the signalling condition in not more than 8 ms from the time that the current starts to decrease.
23、Edition of May 15, 1986 CEPT T/CS*4b-O3*E 2326414 0004854 8 m TICS 46-03 E Page 5 2.3.5. Signal timing When a button is depressed, the signal is output to line. It continues until the button is released. If the signal output is automatically timed, the duration of the signal shall be 70 for the purp
24、ose of data transmission, Administrations must ensure that in practice (e.g.: when the telephone, sender, local line and feeding bridge are associated) the amplitude and duration of transients at the output of the exchange feeding bridge does not significantly increase the level of the mean power tr
25、ansmitted to the national network. Note 5. Signal timing Provision is made here for the timing of signals from the sender to be achieved in either of two ways. Either the signal duration is controlled solely by the length of time the keypad button is depressed, or the sender itself may exert control
26、 on the signai duration in the manner specified. 2.4. Electrical characteristics 2.4.1. Impedance The return loss of the sender against a pure resistance of 600 ohms shall be at least 14 dB in the frequency band 300-3,400 Hz. When a button is depressed the sending efficiency of the telephone set (fr
27、om microphone to line) shall be decreased by at least 60 dB. The impedance unbalance to earth measured in accordance with the principle of measurement in CCITT Recommendation 4.45 6 shall be not worse than or equal to: - in the frequency band 40- 300 Hz: 40 dB; - in the frequency band 300- 600 Hz: 5
28、0 dB; in the frequency band 600-3,400 Hz: 55 dB. During the measurement the telephone set shall be placed on a metallic surface which is connected to earth potential. The sender shall be powered by the line current feed. The sender shall function correctly with either normal or reversed current feed
29、. 2.4.2. Speech suppression 2.4.3. Impedance unbalance to earth 2.4.4. Direct current condition 2.4.5. Overvoltage protection The sender shall be adequately protected, in accordance with national requirements, against overvoltage, e.g. lightning, with buttons either operated or non-operated. The sen
30、der shall operate correctly in the presence of dial tone. Note I. Impedunce The return loss is specified against a pure resistance of 600 ohms as this is in accordance with international practice and maintains a constant reference impedance throughout the specification. However, it is recognised tha
31、t higher impedances are more appropriate for a number of national networks. 2.4.6. Dial tone CEPT T/CS*Yb-O3*E 2326434 0004855 T TICS 46-03 E Page 6 3. Note 2. Direct current conditions The current feeding systems used by Administrations can differ significantly to the extent that it is not possible
32、 to specify requirements other than those stated in 4 2.4.4. However, in order to facilitate the efforts of achieving a common design of senders to meet the requirements of different direct current feeding systerns to be used with push-button telephones, the following information is provided (see U/
33、I diagram, Figure 1 (T/CS 46-03). i) Areas C in Figure 1 (T/CS 46-03) represent conditions which will not occur during normal operation. Their boundaries are the following straight lines: segment a : U = 106 - 1.4 I segment b : U = 53 - 0.3 I segment c : U = 31 - 2.2 I segment d : U = 42 - 3.4 I (U:
34、 Volt; I: mA) and ii) Area A in Figure 1 (T/CS 46-03) represents conditions which may occur in speech state. Its boundary (with the forbidden BB area) is represented by the following straight lines: segment e : I = 25 segment f : U = 1.975 + 0.271 I segment g : U = 8.54 - 0.158 I (U: Volt; I: mA) ii
35、i) Area B in Figure 1 (T/CS 46-03) represents conditions which may occur in signalling state. Its boundaries (with the forbidden BB area) are the following straight lines: segment i : U = 5.17 I segment j : U = 18 I - 60 segment k : U = 6.5 segment 1 : I = 9 segment m : U = 4 I (U: Volt; I: mA) and
36、iv) For a sender during signalling state in areas C of Figure I (T/CS 46-03) there are no requirements. v) During speech state the U/I curve should not enter areas BA and BB. Note 3. Overvoltage protection The overvoltage protection provided should also take care of the effects of the ringing voltag
37、e which might occur with buttons either undepressed or depressed. Note 4. Control tone If a control tone is required by Administrations when a button is depressed, then it is necessary to specify a requirement for the sender such that the tone at the telephone receiver is at an acceptable level, e.g
38、. about 65 to 85 dB relative to 20 pPa measured by a CCITi recommended artificial ear. THE EXCHANGE RECEIVER 3. i. Area of application This Section deals with the receiver or receiver function for use in local exchanges and in private automatic branch exchanges. The receiver shall respond to signals
39、 received over a line from a distant sender conforming to Section 2. The receiver shall be equipped to recognise the sixteen signals designated I to 0, *, #, A, B, C and D. The system may be utilised with only ten discrete signals, in which case the signals designated *, #, A, B, C and D will not be
40、 used; or with twelve discrete signals, in which case the signals A, B, C and D will not be used. Note I: The principles uses of the receiver are expected to be: (a) in a local exchange, connecting with an ordinary subscriber; (b) in a local exchange, connecting with a private automatic branch excha
41、nge, and, (c) in a private automatic branch exchange, connecting with an extension. Note 2: Should the need arise to recognize all 16 signals, it should be possible to adapt the receiver equipment without excessive cost. 3.2. Operating conditions The requirements specified shall be met when the rece
42、iver is installed in a local exchange or a private automatic branch exchange and is thus subject to the environments therein. The relevant climatic conditions are described in Recommendation T/TR 02-03 7, and the receiver must be designed to operate properly within these conditions. Edition of May 1
43、5, 1986 CEPT T/CS*46-03*E D 232b4l14 000485b 1 = TICS 46-03 E O D el I-w (1.5% + 2 Hz) TICS 46-03 E Page 9 A I x I A + 25 dBm y 6dB z U*dBm or x A + 25 dBm x 30 ms May 10 SC 5 30ms Shall not exist SC 30ms May 10 I I 30 ms Shall not cease SC IO ms - - I Does exist May exist I Does not exist deviation
44、 Frequency difference y I frequencies Unwanted z Signal level Signal level x Table 3 (T/CS 46-03). Legend: SC = The continuous existence of signal condition. - SC = The continuous non-existence of signal condition. CRC = The existence of character recognition condition. CRC = The non-existence of ch
45、aracter recognition condition. - i) Depending on the design of the telephone containing the multifrequency sender, the signal condition may be preceded by a transient due to the change in the direct current resistance of the telephone instrument. i) It is pointed out that the maximum permitted delay
46、 time of the sender accompanying direct line current as specified in 5 2.3.5. is 8 ms. This will have an effect on the time for which a push-button will have to be depressed in order to achieve character recognition. Edition of May 15. 1986 I CEPT T/CS*46-03*E 2326434 0004859 7 TICS 46-03 E Page 1 O
47、 3.4. 3.5. 3.5.1. 3.5.2. 3.5.3. 3.5.4. Speech immunity No specification is required. Speech immunity is achieved by presence of the accompanying direct current signal. Electrical characteristics Impedan ce The impedance measured at the receiver input shall be at least 10 kohms over the frequency ran
48、ge For the case when the subscribers line is terminated with the input of the receiver and for testing purposes, a nominal impedance of 600 ohms shall be connected across the receiver. Unbalance to earth The impedance unbalance to earth presented by the receiver and a parallel resistor equal in valu
49、e to the nominal impedance of the exchange termination is measured in accordance with the principles of measu- rement in CCITT Recommendation 4.45 6. When the receiver is connected directly across the line, it shall be not worse than or equal to 46 dB over the frequency range 15-40 Hz and 60 dB over the range Protection against common mode noise The correct operation of the receiver must not be adversely affected when the subscribers line is subjected to common mode noise with a total e.m.f. of less than or equal to 60 volts (r.m.s.) in the range 15-60 Hz. Power fee
