DE1256742B - Time division multiplex transmission system with a large number of channels with pulse code modulation - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

H04j

German KL: 21a4-49

Number: 1256 742

File number: T 23306IX d / 21 a4

Filing date: January 10, 1963

Opened on: December 21, 1967

The invention relates to a time division multiplex transmission system with a large number of channels with pulse code modulation, in which in each pulse frame the code pulses of the same value of all channels in groups are transmitted successively.

In known time division multiplex systems, the information of the individual channels is intermittent successively transmitted, the information belonging to each channel, its current information representing code impulses ordered according to their valence in succession within the dem individual channel available part of the pulse frame. For the transfer of a For a certain frequency bandwidth, twice the repetition frequency of the pulse frame is required.

Each code pulse has a certain period of time available, which depends on the number the channels to be transmitted, their frequency bandwidth and the number of code elements that are used for the representation of an information element can be used.

An increase in the number of channels therefore requires a shortening of the code pulse duration cannot be achieved by known coders.

A time division multiplex system with pulse code modulation was also introduced in the German Auslegeschrift 1 065 030 known for high channel numbers, in which for the conversion of the instantaneous amplitudes of the messages into groups of code pulses for each channel is provided with a special encoder, all of which work simultaneously, and at which the output voltages the encoder to form the multichannel pulse series are scanned in such a way that the code pulses each have the same valency of the individual channels.

In this known system, each channel encoder encodes an instantaneous value with time expansion during the duration of a pulse frame. There is not only a separate encoder for each channel required, there are also high demands on the phase accuracy of the sampling pulses, since the The total number of sampling pulses in a period is equal to the number of code pulses in a pulse frame.

Devices have also become known for the remote transmission of measured values which combine frequency and time multiplex transmission (article by Karger and Unger: "Frequency multiplex remote transmission of measured values" in "Archive for technical measuring", V 386-2, November 1962, p. 249). With these devices, a plurality of frequency-modulated, measured values are time-division multiplex transmission systems higher
Number of channels with pulse code modulation

Applicant:

Telefunken

Patentverwertungsgesellscttaft mb H.,
Ulm / Danube, Elisabethenstr. 3

Named as inventor:
Helmut Oberbeck, Backnang

Transmit adjusting signals intermittently. If the number of channels is high, these facilities cannot

provide ao parts compared to the known time division multiplex transmission systems with pulse code modulation, because with them, too, only the information value of one channel is transmitted at a time. In contrast to this, in the known frequency multiplex systems, the information is all Channels always transmit at the same time, because the individual channels - preferably in the form of a Sideband - by means of subcarrier oscillations and through multiple modulation in the for transmission suitable location in the broadband transmission channel. With these frequency multiplex systems is the expenditure on subcarrier oscillations and modulation devices for large numbers of channels considerable.

In a transmission system with a large number of channels, there is the task of providing the necessary Significantly reduce effort.

Naturally, in a time division multiplex system, the number of code pulses required for a quantity of information to be transmitted per unit of time cannot be reduced any more than the transmission bandwidth required in a frequency division multiplex system.
The object is achieved by the invention specified in the claim.

In the transmission system according to the invention, in contrast to the known time division multiplex systems Not only the information of one channel at a time, but simultaneously and in sections each transmit the information of several channels. There is the advantage that the known transmission systems for many channels

709 709/161

Claims (1)

Required expenditure on channel encoders or subcarrier oscillations is considerably restricted can be. The invention is applied to a time division multiplex transmission system having, for example, 1920 channels may, explained. For example, every 120 speech channels are combined to form a broadband channel, i. h., they are offset in frequency from one another in the manner customary in carrier frequency technology so that together they form a carrier frequency channel with a broader frequency bandwidth. If the basic channels are speech channels with a bandwidth of in each case 4000 Hz, the broadband channel has the bandwidth B = 120-4000Hz, while the number of broadband channels Z = 1920: 120 = 16. The same is obtained for the duration of each code pulse Duration as in the known systems, but there are only groups of in each pulse frame 16 code pulses available. The number of groups is equal to the maximum number of code pulses, which are formed when a momentary value of the message flow is recoded can. The pulse frame frequency must be at least twice the above-mentioned highest transmission frequency B of any broadband channel. The duration of the pulse frame is because of the larger Transmission bandwidth of each broadband channel according to the number of combined basic channels shortened. For the transmission, an encoder is used for each of the sixteen broadband channels encoding each pulse frame. However, since the number of broadband channels is low, steal a relatively larger proportion of the pulse frame is available for each transmission pulse, so that the requirements be reduced in terms of the phase accuracy of the pulses. The scanning pulse sequence then scans the code pulses of each broadband channel via gate circuits known per se and combines them with the code pulses of the other channels to form a time-division multiplex pulse train. Claim: Time division multiplex transmission system with a large number of channels with pulse code modulation, in each of which Pulse frame the code pulses of the same value of all channels in groups in succession are transmitted, characterized in that in each case a number of channels by frequency division multiplexing to form a broadband channel combined and all broadband channels each by an assigned encoder simultaneously are encoded with the generation of a time-expanded code pulse sequence from which is known per se By periodically blanking the code pulses prescribed for the transmission Duration can be taken from and with the code pulses of the other broadband channels in groups are successively joinable. Considered publications:
German Patent No. 1,008,793;
German interpretative document No. 1 065 030.