SU1083380A1 - Digital information transmission system - Google Patents

Abstract

DIGITAL INFORMATION TRANSMISSION SYSTEM, containing on each radio station a serial HeHHbie terminal transmitting unit and a transmitter and serially connecting. A receiver, a demultiplexer and a terminal receiver unit, and at the repeater are combined on the input and receivers, information outputs of which are connected to the transmitter input via a multiplexer, which, in order to simplify the system, a controlled frequency generator is inserted into each radio station , the output of which is connected to the clock input of the terminal transmitting unit, and the input to the additional output demultiplex, and a phase evaluation unit is inserted in the repeater connected between the clock outputs of the receivers and additional Additional input multiplexer,. the reference output of which is connected to I the corresponding input of the evaluation unit, phase, where n is the number of radio stations.

Description

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The invention relates to a radio communication technique and can be used to transmit information through a repeater, in particular for organizing communication with mobile objects (similar to the Altai network) or in satellite communication systems.

A known system for transmitting digital information, containing information sources and a frequency access (compaction) unit at the ground stations, and a frequency division unit, demodulators and a time compaction unit at the repeater. The system’s lack of periodic errors is the type of insertions or precipitations of symbols due to asynchrony clock-frequency stations and repeater. Although the frequency of these errors is quite small, they lead to frame synchronization failures, after which the reception of information is usually impossible.

Closest to the proposed is a system for transmitting digital information, containing on each radio station serially connected terminal transmitting unit and transmitter and serially connected receiver, demultiplexer and terminal receiving unit, and transmitting integrated on input n receivers, information outputs of which are connected to multiplexer 12 transmitter input.

A disadvantage of the known system is the difficulty of having several complex digital devices on the repeater.

The purpose of the invention is to simplify the system.

To achieve this goal in a digital information transmission system containing a serially connected terminal transmitting unit and a transmitter and a serially connected receiver, a demultiplexer and a terminal receiving unit at each radio station, and at the repeater there is an annotation on the input n of receivers, whose information outputs are connected to the input a transmitter, a controlled frequency generator T of the clock frequency is input into each radio station, the output of which is connected to the clock input of the terminal transmitting unit and the input is with the additional output of the de-multiplexer, and the repeater

A phase estimator is inserted, connected between the clock outputs of the prremnikov and the auxiliary input of the multiplexer, whose reference output is connected, to the corresponding input of the phase estimator, where n is the number of radio stations. ,

FIG. Figures 1–4 give the block diagrams of the transmission system, b-local phase estimation, the demultiplexer, and the controlled clock frequency generator, respectively.

The digital information transmission system contains on the transmitting radio station 1 the terminal transmitting unit 2, the transmitter 3, the control generator 4 clock frequencies, the receiver 5, the demultiplexer 6, the terminal receiving unit 7, and on the repeater 8 n receivers 9, the multiplexer 10, the transmitter 11, a phase evaluation unit 12, wherein the phase evaluation unit 12 comprises a switch 13 and a phase detector 14, a demultiplexer 6 a frequency divider 15, a first selector 16, a second selector 17 and a decoder 18, and a controlled frequency clock generator 4 a group frequency multiplier 19, control divider 20 and divider 21.

The transmission system operates as follows.

Terminal transmitting unit 2 is necessary for matching the connecting line with the station equipment and contains an analog-to-digital converter, if necessary, a time-multiplexing unit (multiplexer), its output is a digital signal with a clock frequency F supplied to the modulations input of the modulator located in transmitter 3. The latter transfers the signal to the radio frequency, amplifies and radiates to the radio channel.

The signals emitted by the stations at different carrier frequencies f jfj, ..., f are detected by the corresponding repeater receivers 9, having information and clock output. The multiplexer 10 during a cycle of duration 1 alternately switches all outputs from: the demodulator drives so that during this time there are n + i pulses at its output, where n is informational and i is service. service for specificity requires one pulse for frame synchronization, and one pulse for transmitting information generated by the unit 12 phase evaluation. The multiplexer output group signal enters transmitter 11, the functions of which are similar to those of transmitter 3. Phase estimation unit 12 compares the clock phase of the output signal of each demodulator with the multiplexer cycle frequency F, determines the difference and enters its value into the group signal by additional multiplexer input. In a specific example during the cycle time. one bit of phase information is transmitted. To transmit information about the phase of the receivers with k bits per sample Need to kn kn. Thus, all the information about the phase can be transferred in kn cycles and to extract it, a superframe value equal to kn cycles is necessary. A possible block diagram of block 12 is shown in FIG. 2. It contains a switch 13, sequentially switching the clock outputs of receivers 9 to the input of the phase detector 14, to another input of which the cycle frequency from the multiplexer is fed. The output of the phase detector represents the phase mismatch value in a digital code suitable for input into a multiplexer. The group signal is received by the receiver 5 of each station and fed to the demultiplexer 6, extracting the km from the group signal an individual information signal intended for the station. The terminal receiving unit i7 is designed to interface with the connecting line and contains a digital-to-analogue conversion node. The demultiplexer 6 (Fig. 3), like the multiplexer, is a typical element, a certain complication is connected with the necessity of separating the superframe. The demultiplexer consists of a frequency divider 15 connected to the control inputs of the first 16 and second 17 selectors, and a decoder of the 18 cycle and super cycle. Signal inputs and p outputs of the first selector are signal inputs and outputs of the demultiplexer. (n + 1) -th and (n + 2) -th signal outputs of the first selector are connected respectively to the inputs of the decoder 18 and the second selector 17. The output of the decoder 18 is connected to the installation input of the divider 15, the clock frequency (n + i) F. The output of the second selector is an additional output of the demultiplexer, through which the phase error information is derived. The multiplexer has a similar structure, with the exception of the second selector, which in this case is located in the switch of the phase evaluation device, and changes the location of the information inputs and outputs. Selectors can be executed, for example, on a 155KP5, 155IDZ microcircuit, etc. The decoder consists of a shift register and a multi-input circuit I. The controlled 4-clock oscillator is used to adjust the frequency and phase of the channel clock frequency to the group (multiple or fractional) frequency of the multiplexer 10 repeater. One of the options for constructing a controlled clock oscillator 4 is shown in FIG. 4. The controlled oscillator 4 clock frequency contains connected after-. a multiplier 19 of the group frequency, a controlled divider 20 and a divider 21. The output of the multiplier 19 has a frequency that is a multiple of the frequency of the multiplexer. The controlled divider 20 according to the commands from the transponder embedded in the additional time channel of the group signal adjusts the phase of the output signal so that the emitted clock frequency and phase are adjusted to the multiplexer cycle signal. When transmitting a digital signal from an external source in the system, the terminal transmitting and receiving units do not contain analog-digital and 1Ц1 analog converters, but must have corresponding asynchronous input and output nodes. Thus, inputting the phase of individual signals relative to the group cycle signal at the repeater of the device, transmitting the evaluation values at the station by inputting the group signal in the multiplexer and correcting the phase of the emitted individual signal at the station significantly simplifies and cheapens the system by eliminating the retransmission A torus of several asynchronous input devices (reducing its mass, volume, power consumption) and increasing the reliability of the system.

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Claims (1)

DIGITAL INFORMATION TRANSMISSION SYSTEM, containing at each radio station a terminal transmitting unit and a transmitter connected in series and connected in series. a receiver, a demultiplexer and a terminal receiver unit, and on the repeater are connected at the input of η receivers, the information outputs of which are connected via a multiplexer to the transmitter input, characterized in that, in order to simplify the system, a controlled clock generator is inserted into each radio station, the output of which is connected to the clock input of the terminal transmitting unit, and the input is connected to the additional output of the demultiplexer, and a phase estimator is inserted into the repeater, connected between the clock outputs of the receivers and the input of the multiplexer, the reference output of which is connected to the i corresponding input of the evaluation unit. " phase, where η is the number of radio stations. 1 1083380 2