DE2252540C3 - Code division multiplex method for the transmission of messages over a binary channel - Google Patents

Description

speaks, . .

that this sum signal as binarized in aen binary message channel is fed, * °

that on the receiving side for the recovery of the

align bits an analog sum signal is formed so that with every jump in the mod _- Sum signal the respectively existing output signal an amplitude level of the duration of a sequence bit is added and that then the analog sum signal in in a known manner, for example, is further processed by a correlator

2. The method according to claim 1, characterized in that the transformed sequences on the transmitting side of the news sources are added to each other in any phase position mod 2.

3. The method according spoke 1, characterized by zei.quantisiert transmission of the transformed Binary sequences, so that all partial sequences of the mod 2 sum have a minimum phase shift (/ ") Show against each other. _

4. The method according to any one of claims 1 to j, characterized by the receipt se.t.ge recognition of the message bits by correlating the differentiated and rectified Ong.nalsequenz (Λ ,,,) with the differentiated and rectified mod 2 sums .gnal (T). ^

fanesstation recognizes your sequence and thus your message through correlation reception. In the case of a binary j ^^ j _{, however,} the addition of the hinzelsequenzen is not

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invention

Invention iiegi u't. ^ (, _Tl

_NaCN directed channel that only two states Überei ^ _{n ejn} collectively messages after

r_2 _emuU j _p iex method with great freedom from errors to Coflem ν

_D i _eS e object is achieved according to the invention in ^ the transmit side to be transmitted sequences ^ respective news sources h usually such iran _{forrmert we} re that the Uänsiormierte Se ₄ UCiU polarity always changes when a bit of the original is [provided that the transformed se-

"J" of _the individual news sources in each case

Χ. _ςρηνε! .,; _{ςη (} Λεη mod 2 are added, so that a P ¹ ^ ₀ , _{ge arises} , which corresponds to the mod 2-sum of all con.-that this sum signal! _{aK is fed into the} binary message channel £ on the receiver side for the recovery of the wiro, '^ _ej - _ana f _oges sum signal thereby J, tj, ^' ^ (] _a ß with each jump in the mod 2-sum-ο ^^ respectively existing output signal a length level of the duration of a sequence bit «, add-απη ^. ^ ^ _{that then} the analog sum-

is generally further processed in a known manner, for example by means of an Sn correlator. nen ^ _Erf . _invention also _{makes it possible} to transmit, code division _{b bi ä Kan} ai _e such. B. signal ^ ^{uD (} J _{f | eitu which e.g.} the practice of _a ^^ ^ ^^ ^^

Statec »L c ¹ ^ _{can also do radio} .

al ^ '° g ^ische »^ ^l ^ _d > _e synchronization ^{measure e} " ^se ^ / ^ ^W ^^ _d f _s integrated telephone and men msb ^^^ η weiden . Send the ver data network y _{lle ellen the} transformed sel ^{"e" "s} ^ _{n most po} i _ger phase, then the Tpilrehmerz-h! can be increased without

. ^ "^""" Βη due to incorrect correlation correct jump ^ _Ausscndungcn

Net _binary sequences are quantized in time. so d ^ transfo m.e_rte _B ^ _tfchler quite considerably.

^^ ™ ^ * ,. Improve the detection ^ _Nac hrichtenbits at the receiver when the correlation with the differentiated and gleichgerichte-

The inventors «» »l« "m a Cod.muHlp.ex-Verfahr. ,,

for message transmission via a binary channel,

carry.

Hs is known to transmit messages over

Se _frfi nd _rg """a" H ^ i from A _us ",""

examples explained in more detail, ts Z (JgI.

^r ninpUcrhalthild a circuit arrangement F ^. 1 Bocksclialt '' ^ια "" ^ - _R - method

partially affects. Also the transmission of the PCM signals η Net / .kiKiien is very complex.

In flexible systems such as B. in the Nachrichtenühcrtrapmm Satellite systems such as the code division multiplex method are therefore also used via satellites cinueset / t. Here each transmitter modulates the actual ones Nachnchtenbi.s with a recipient-specific binary sequence /. and sends this out periodically, without any consideration of the phase position of the transmitted sequence to the sequences of other stations. All incoming sequences are added up in the satellite converter, amplified, and sent out again. Every reception

direction _t ^ _transmission .

'''' * = ■ '^ "i.;" I, »y ςίοη-ιΐ ^v V which

canal, whose Cf ^ 'P ^

already after according to the invention, ^ rtahrc. to be gemäßenJ ertahren _fed; ent stood, st, by the NachC ^ "^^ 'he ^f» ^^ ^ld messages according to "'. For this purpose, the ^d bits of the message source bit «. : y

* 5 generator 3 in known W s, positive and _ tive binary sequences and an sei heß '.1 d η e.ner r ns format.onseinnchtung ^ gemassdemernn ^

Process converted. The exit of the Iranslor

mation device leads to the second input of a moi 2 adder 5, the first input of which is that of the Message source 2 still unmodulated code division multiplexed signal -} - '(is supplied.

At the output of the mod 2 adder 5 there is now that which is also modulated with the message from the message source 2 Code division multiplexed signal

Λ / = -Ki ©} 't available (Θ = mod 2 addition), which is forwarded via channel 6.

The receiver E is connected at any point on the outgoing line 6. Among other things, it contains, for example, a device 7, the input of which is connected to the transmission channel. an integrator 8, in front of whose negative input, for example, a delay line 9 is connected, and a correlator! 0.

The free input of the delay line 9 and the oppositely polarized, here positive input of the integrator 8 is connected to the output of device 7. The output of the integrator 8 contains the analog Codemuliiplexsignal S, from which in known The messages are recovered bit by bit by the downstream correlator.

FIG. 2 shows the mode of operation of the exemplary embodiment shown in Hg. 1 on the basis of a time diagram for the signal processing. The abscissa of the time diagram is time t.

The incoming code division multiplex signal 1>', · (line 1 ) is to be modulated by the transmitter .V with the message bits converted into sequences Xk (line 2). This modulation is done by mod 2 addition.

Since the mod 2 summing signal is not inferred on the polarity of a single transmitted sequence (the polarity is continuous through the other signals changed), so the information is only in the jumps (0-1) and 1-0 transitions) of the mod 2 sum, the original sequences must first be transformed before they are multiplexed with the code signal in the mod 2 adder ϊ), can be added. According to the invention, the polarity of the transformed sequence is> Ά · (Line 4) always changed when one bit of the original sequences /. Λ; .- ι line 2) is available.

The result of the mod 2 addition of transformed sequence ) ' _k (line 4) multiplex signal i:)', (line 1) is the multiplex signal M (line 6).

This method ensures that every signal jump; in the binary code division multiplex signal a positive jump or the presence of a bit of the original sequence can be recognized. this fact is used at the receiving end to recognize the original sequence.

The pulse length of the bit clock of the message source and the original sequence are matched to the receiver. By correlating the original sequence with the received code division multiplex signal, the recipient tries to select a message intended for him. For this purpose, the code division multiplex signal M is differentiated and rectified in the device 7 of the receiver, so that the pulse train T (line 7) is produced. This pulse sequence is fed directly to the positive input of the integrator and, by the bit clock duration // (delayed, to the negative;) input of the integrator.

Each pulse arriving at the positive I ing.ing of the integrator causes an increase in the output signal of the integrator corresponding to the area of the pulse, each pulse arriving delayed at the negative input of the integrator causes a decrease in the output signal of the integrator. The pulse v, generated only by the first pulse of signal 7 ~, is inclined in line 8. Since the delay time of the delay line 9 is ιii , the pulse duration of the pulse.V] is exactly in- From the second pulse of the pulse train Γ, the result is the same YVei :: the pulse s * in line 9 etc.

Since the pulses are superimposed in the integrator, the sum signal 5 = 1.S7 arises at the output of the integrator 8, which corresponds to the known analog code by L ^ i ^ Xolgniii 1ItI

. * A .. 11
^ L. nüS ui

Γ.απιι aiisv. l

ßend in a known manner by the correlator 10 the message can be selected and expanded as a sequence of message bits .V.

When using noise-like sequences - and it is precisely these that are of interest for the transmission of sequences that are arbitrarily out of phase with one another - there is no strict orthogonal system. since the cross-correlation coefficient of a certain sequence with the sum of all other sequences does not vanish. It is therefore necessary to use very long sequences that contain so much similarity information that they can be found with great probability in the sum signal. In order to be able to use shorter sequences, it is therefore advantageous not to use the analog sum signal from signal T (line 7) S (bottom line), but to correlate the signal Γ directly with the signal Λ; .-, / (line 5).

This signal Λ ';, -, / is created like the signal T (cell 7) by differentiating and rectifying the binary sequence assigned to the receiver in the correlator )' i, - (line 4). As a result, the delay line 9 and the integrator 8 are omitted in the receiver, so that the modified correlator 10 in this case receives the pulse train T directly from the unit 7.

In Fig. 3 is for the preparation of the code multiplex signal according to the invention an advantageous Blockschaltuni! a transformation facility 4 specified. It is composed of an AND element 41 two inputs, whose Aiisnangstakt cine bistabile Tilt stage controls. The inputs of the multivibrator are connected to one another.

The first input of the AND gate 41 is supplied to the bit clock signal Tu (line 3 in Fig. 2), the second input of the transforming binary sequence Xk (line 2 in Fig. 2). Are both signals in the same

^{If the} polarity is present, the AND element emits a signal which switches the trigger into the other stable state. The transformed Binärscqucn /) \ - (line 4 in Figure 2) may be one of the two outputs of the flip-flop 42 are taken directly. In the code division multiplexing method according to the invention, it is advantageous if the individual sequences are mutually phase shifted / _; , which is at least as large. like the reciprocal of the cutoff frequency / j, the channel-. Sending and receiving

^f 'elektn.nik. This phase shift can be achieved in a known manner by time quantization. For this purpose, the secondary sequences Jet of individual news sources are phase-shifted by the zen / ,, \ j “ (lines 1 and 2 in FIG. 2).

^f> 5 The phase shift of the various binary sequences is achieved by accepting a specifiable meter probability, but also by randomly sending out the binary sequences.

For this purpose 2 sheets of drawings

Claims (1)

Patent claims: 1. coaemuiupiex-νcuanii.il ^. Transmission over a binary channel in which a large number of sources transmit messages in the form of a binary sequence per message bit, characterized in that on the transmitting side the sequences to be transmitted aer the respective message sources are first transformed in such a way that the transformed sequence always changes its polarity , if a bit of the original sequence is present, that the transformed sequences of the individual message sources are each added mod 2 out of phase, so that a binary sequence is created which corresponds to the mod 2 sum of all components.