SU924911A2 - Device for compressing of facsimile signal frequency band - Google Patents

Description

one

The invention relates to communications and can be used in apparatus for transmitting a facsimile signal with band compression.

According to the main author. St. No. 708535, there is a device for compressing a bandwidth of a facsimile signal, which contains in the transmitting part a block of video signal fronts, an analog adder, the output of which is connected to a filter, a ring counter; the input of which is connected to the output of the video edge selection block, the outputs of the ring counter are connected to the inputs of the analog adder, and in the receiving part an amplifier whose output is connected to the inputs of four threshold elements, a multiplier consisting of two inverters and two two-input logic. And, whose outputs are connected to the inputs of the output adder, one input of each of the logical elements I is directly connected, and the second input is via an inverter, a torus with the output of the corresponding threshold element.

However, the known device does not have sufficient noise immunity. This manifests itself in disrupting the ordering of the formation of a multilevel signal in the development of hardware failures, which leads to distortions of the received information.

The purpose of the invention is to improve noise immunity.

Claims (2)

To achieve this goal, an inverter and two AND elements are included in the device. Compress the facsimile signal band (in its transmitting part), the first input of the first element AND is connected to the first input of the second element AND through an inverter, the second inputs of the first and second elements AND are connected to the output of the first trigger of the ring counter, the third inputs of the first and second elements And are connected to the output of the second trigger 3 of the ring counter, the fourth inputs of the first and second elements And are connected to the output of the third trigger of the ring the counter, and the output of the first element And is connected to the first installation input of the fourth trigger of the ring counter, the output of the second element And is connected to the second installation input of the fourth trigger of the ring counter. FIG. 1 shows a circuit diagram of the transmitting part of the device; in fig. 2 timing diagram, the work of the transmitting part of the device; in fig. 3 and t are respectively the electrical circuit of the receiving part of the device and the time diagram of its operation. The facsimile signal band compression device contains in the transmitting part a block 1 of the video signal fronts, analog adder 2, filter 3 ring counter k, performed on the S triggers, inverter 6, first 7 and second 8 And elements, and in the receiving part - amplifier 9, threshold elements 10, a multiplier T1 consisting of two inverters 12 and two two-input logic elements I 13, as well as an output adder 14. The device works as follows. The source signal (Fig. 2) is fed to the edge selection block 1, from the output of which the signal (Fig. 25) goes to the input of the ring counter k, performed on the flip-flops 5, from the output of which the signals (Fig. 2 6, 6.6 ) are fed to the input of the analog adder 2. From the output of the adder 2, the signal (Fig. 2.) is fed to the input of the filter 3, where its envelope is selected (Fig. 25). Signals 6, 1, d simultaneously arrive at the inputs of the first 7 and second 8 elements I. The input of the first element And 7 receives the signal (Fig. 2q) from the input of the device, and the input of the second element And 8 receives the inverted signal Q from the output Invetora Outputs of the first 7 and second 8 elements And are connected respectively to the zero and single installation inputs of the fourth trigger 5 of the ring counter H. From the timing diagram of the transmitting part of the device (Fig. 2), it is thus seen that the trigger of the rings is forced th counter k, thereby significantly reduced voro tnost forming unordered multilevel signal. In the receiving part of the device, si-nal (fig. K) is amplified by amplifier 9 in the form of an analog signal and fed to the inputs of the threshold elements 10. From the output of the threshold elements, the signals (fig. TK.AMH) in the form of square pulses go to the inputs of the multiplier 11 , and the multiplication is performed in pairs with the inversion of one of the signals (Fig. itO, n). From the output of the multiplier 11, the signals (Fig. Ap, c) are fed to the adder 1, from the output of which the pulse train is removed (Fig. AT). Thus, the use of the proposed device significantly improves the noise immunity of the facsimile signal transmission equipment. Claims: Bandwidth compression device, facsimile signal by aut. St. No. 708535 characterized by the fact that, in order to improve noise immunity, an inverter and two elements AND are included in the transmitting part of the device, the first input of the first element AND is connected to the first input of the second element AND through an inverter, the second inputs of the first and second elements AND trigger ring counter, the third inputs of the first and second elements And connected to the output of the second trigger ring counter, the fourth inputs of the first center of the second elements And connected to the output of the third trigger ring counter, and the output of the first element I is connected to the first installation input of the fourth trigger ring counter, the output of the second element I is connected to the second installation input of the fourth tri1-ring ring counter. five I I I 111 II I T w ten to IB f3 f2 13 / 2