Patent GB-1300003-A (GB)
Title: Telecommunication exchanges
IPC: H04J3/12
Filed: 1970-03-24
Abstract: 1300003 Automatic exchange systems INTERNATIONAL STANDARD ELECTRIC CORP 24 March 1970 [1 April 1969] 14220/70 Heading H4K In a TDM, PCM exchange in which, on the incoming and outgoing highways, synch. signals occupy the first channel of each frame and channel signal data occupies one other channel of each frame such that data in respect of all the channels requires a number of successive frames (a super frame), the channel signal data is transmitted through the exchange during the one other channel and also during the synch. channel since this is not normally utilziedwithin the exchange frame. If one assumes a 32 channel frame K0-K31, synch, data is sent during K0 and channel data in respect of two or even four channels is sent during K16. Consequently 16 or 8 respectively successive frames are needed to transmit the data in respect of all the channels. (The channel data in the last frame of the succession relates to the synch. and data channels and thus forms super-frame synch, data.) The contents of the channels on e.g. four incoming highways are buffered in a so-called group store which is read-out on a cyclic basis for transmission via a space division network to a time slot interchange memory in a junctor. Considering Fig. 2a, the eight serial PCM speech bits of channel K17 on each of highways HI ... HIV are stored in sections 1..4 respectively of a speech store SpS. The speech of the channels K18 is stored in sections 5-8 and so on. The synch, data in the channels K0 is stored in sections 61-64. The channel data relating to channels K1 and K17 and occurring during channels K16 on each of the highways is stored in sections 125-128. As shown therefore the store contains data relating to the first frame R1 of the exchange cycle which is slipped by half a frame relative to the highway frame. During frames R2 ... R16 the only data which is radically different from that in frame R1 is that in sections 125-128 since this is channel data in respect of a different pair of channels in every frame, the data MRSY in frame 16 being super frame synch, data. A data signal store SiS is also provided. This is only written-in once per frame (of each highway) when the channel data occurs. Thus for frame R1, sections 1 and 65 are simultaneously filled with (4 bit) channel data in respect of channels K17 and K1 of highway HI during the time slot in which section 125 of the speech store SpS is filled with this same channel data. Consider now a connection between channel K17 on highway HI and channel 26 on highway HIII in conjunction with Fig. 3. During the first time slot Z = t l = 1 (Fig. 2) section 1 of the group speech store SpS is read-out and the PCM bits therein are conveyed in parallel via the space division network (crosspoints controlled by portion SC1 of a space path store in junctor VSP) into section Z1 of the speech store SpS in the junctor VSP. The previous contents of this store section are conveyed over the Return wires of the same crosspoint to a dynamicizer W, i.e. a parallel-serial converter, associated with the group store GSP for outward transmission along K17 of highway HI during the time slot 17 of this highway. Since it is assumed that we are concerned with frame R1:-the content of section 1 of data store SiS in the group GSP are transferred to section 61 of this same store; the crosspoint addresses in section 1 of store SC1 are transferred (without destroying the information in this sction 1) to section 61 of SC1 and the contents of section 1 of SiS in VSP are (destructively) transferred to section 61 of this same SiS. Similar operations occur for the other channels K17 on highways II, III and IV but sections 62, 63 and 64 respectively of stores SiS and SC1 are involved on these occassions. During frame R1 when Z = 61 (which corresponds to the first or synch. channel on a highway) the data in SiS of GSP is transferred via the network to section 1 of SiS in VSP so that it is reunited with the pseech data in the section of junctor VSP's stores reserved for the considered connection. Meanwhile the data in section 61 of SiS in VSP is transferred via the same network path (Return wires) to a signal sender which will compound the data for K17 with that for K1 and transmit it during K16 of the current frame on the outgoing highway HI. During R1, speech but not data in respect of K26 HIII will be transferred between section 1 of SPS in GSP and VSP under control of the space path SC2 and time path TC memories in the usual way. When frame R10 occurs, channel data for K26 HIII is present in section 39 (and 127) of the data store SiS (and SpS) in the group equipment GSP. Speech is transferred as before during time slot Z = 39 between the section 39 of group store SpS and section 1 of junctor store VSP, the previous contents of the latter being passed to a dynamicizer for transmission during K26 along the outgoing highway HIII. The space path SC2 and time path TC memories are written with crosspoint identities in sections 63 and the contents of section 39 of the group's SiS are written in section 63 of the same store in a manner similar to that previously described for section 1 during R1. When time slot Z = 63 occurs, data transfer takes place, the previous contents of section 1 of SiS in VSP this time being stored in the signal sender ZS for compounding with the data of channel K10 for transmission during K16 of the current highway frame. Figs. 4-6 (not shown) depict the data flow and control actions described above. If, in the example, one of the channels had been numbered 1-15 then its data would be transferred in an analagous manner during the time slots Z = 125-128 of each frame, c.f. Fig. 2, viz. during the occurrence of data time slots on the highways. Specifications 1,261,599, 1,269,888 and Application 19274/70 should be consulted for further details of some aspects of the above system.