DE1804814C3 - System for the transmission of binary-coded messages - Google Patents

Description

Message transmission systems are still mixed by correlating their address with this became known with time function multiplex, such as mixed news.

With such a correlation, the autocorrelation function arises (AKF) and the cross-correlation function (KKF). The AKF delivers the message to be received, the KKF delivers noise. For reasons of the signal-to-noise ratio, it is necessary to increase the AKF to a maximum and keep the KKF as small as possible. This task can be solved exactly, v.vnn the transferred time-dependent message functions are orthogonal functions.

The following applies to orthogonal functions

when T is the sampling instant. / (r) is the cross-correlation function. The following applies to the autocorrelation function I ₁ (1) for orthogonal functions:

I ₁ (/) has a maximum at time t = fine.

Functions that are orthogonal to one another lose their orthogonality even with slight temporal shifts from one another, so that the KKF becomes greater than zero.

It is therefore advantageous to ensure that all time functions arriving at the receiver of the satellite have a fixed temporal assignment to one another, which ensures their orthogonality. This fixed assignment is made possible by the different transit times between the ground station and the satellite difficult. The problem is solved by having each ground station monitor and postpones the messages it broadcasts itself in such a way that orthogonality is guaranteed.

If there are several ground stations involved in the traffic, which may not transmit for a long time, so is it is advantageous to provide at least one "mother station", d. H. a ground station that addresses constantly sends out. These addresses iii.ci then go to the above Synchronization can be used.

Such a parent station is generally advantageous because it helps synchronize of all ground stations is made easier because a fixed reference clock is always available.

As described, the system according to the invention can be particularly advantageous when using operate orthogonal functions. These differ from non-orthogonal functions, such as executed, only because of the more favorable signal-to-noise ratio. In principle, other functions are also suitable.

Such functions can still be found under the orthogonal functions, for example with the help of an electronic computing system, which have the property with small time differences with each other, as they occur as a result of small inevitable synchronization errors of the ground stations can cause only a slight increase in the cross-correlation function KKF, so that the message transmission is less sensitive to such errors and the disruptions that result from them will.

1 sheet of drawings

Claims (5)

Radas and SSMA, in which a cyclical transmission of the messages is provided for, however Claims. ^. ^ _{fote assignment of} schedules more pre- 1 System for the transmission of binary coded seen _R « ^L _fahfcn ^ _{jn the Ayf} Nights between ground stations under Ein 5 uas ¹ ^ ¹ - "". . ".. ^ auds switching of one or more satellites, in which and Satellite Commun.cat.on "by H. M ag η usk, ^{send all Bod 8} e" ^ onen ^ LSg and / or he.-Bus given to the> Nat, onal Sympos.um Received on Space at the same time and addresses with information Electron.es and Telemetry «.η Miami Beach Florida, transmitted via the transmitter and / or receiver, in 1962. In other words, it is characterized in that each ", ei" night transmission system, for which all addresses have the length of the message bit, earth stations gle.chzeit.g send and / or receive and receive the intercepts to be transmitted in their polarity . ₇ ■, -. This method, st a mixed time-frequency- Earth stations are sent that in the satellite multiplex method, in which each message list receiver has the addresses of all earth stations, ₅ characters divided into short equally long time segments and a fixed time allocation to each other. During these periods of time, a message is sent mixed together to form a message that all addresses in front of the external carrier frequency selected from a large number in the satellite are in each case. The stringing together of a specific sequence and that each receiving ground carrier frequency represents a specific address station the message intended for it by * o, which identifies both a message character and the correlation of its address with the message recipient,
mixture determined. In the process, however, individual carrier 2. System according to claim 1, characterized by identifying frequencies during the short periods of time, that the addresses are used at orthogonal times by different senders functions are. 25 This leads to message falsification or 3. System according to claim 1 or 2, marked simulations. is characterized by the selection of such time radio. In the SSMA process are compared to the This means that if there are deviations from the fixed duration of the message characters, they will be very long temporal assignment, the ratio of the binary sequences is used as the address, their clock frequency Autocorrelation function for cross-correlation 30 is also much higher. A message sign function changes little. thus always corresponds to a section of the binary sequence. 4. System according to one of claims 1 to 3, all transmitters have the same frequency band characterized by at least one permanently available. The determination of each for the individual transmitting ground station. Participant-specific message is carried out by correcting 5. System according to claim 4, characterized in that the signal mixture is marked with the address of the draws that a ground station for deriving subscriber. In this process, the disturbance is pure The reference clock for the other ground stations was relatively unfavorable and the synchronism constant sends. The long address sation time is very long. The invention is based on the object 40 specify the system for the transmission of messages, the one against the SSMA method and the The transmission of messages between ground RADAS methods improved signal-to-noise ratio enabling stations with the activation of satellites, light provides. the broadband capability of the system makes the task possible kcit a very extensive messaging 45 given invention solved. Advantageous further training lung. Usually the messages are coded in binary of the invention are described in the subclaims Transfer form. ben. In order to take advantage of the transmission path, the invention is illustrated below with reference to FIG multiplex systems known. A method for over- mapping explained in more detail. transmission of electrical signals, which together with 50 The figure shows identification signals transmitted in one channel for a single ground station and a sequence of message bits that is supposed to represent the successes again separately with the help of the identification signals. This is shown in dashed lines and is described in DT-PS 12 09 151. The now actually transmitted, a higher clock frequency identification signal, the sequence of address bits with each useful signal, which is transmitted within, is used to control a counting circuit 55 of each individual message bit, the address "LOLLOL" or a Slromtores, which in turn is sent out by a device. The polarity of this sequence includes individually activated for each message source in order to transmit the message. All ground stations reproduce the useful signal of the message - send their message in this way, whereby they all allow sources if its corresponding signals send or receive at the same time. It is to be received. Time division multiplex systems do not necessarily have the disadvantage that all ground stations do have the disadvantage that each participant is constantly transmitting. In the satellite receiver, the post-office space received by the message transmission at the time allocated to it must be adhered to precisely within the time frame. are combined to form a message mixture, transmission time is lost, which is transmitted for the syn- thes after amplification if necessary, chronization and address transmission expended 65 The ground stations involved now determine what must be used for. they specific messages from the news