SU1483664A1 - Device of frequency-shift-keyed signals - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to improve noise immunity. The device contains an input signal converter 1, a differential detector 2 consisting of a subtraction unit 13, filters 14 and detectors 15, keys 3, 6 and 10, limiters 4 and 5 above and below at zero level, threshold blocks 7 and 8, el - The t is NOT 9, the inverter 11, and the registration unit 12. In the device, the channel is switched off with strong interference and the signal is detected in another channel. In this case, the absence of a signal in the connected channel indicates the presence of a signal in the channel with interference. 1 il.

Description

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The invention relates to radio engineering and may find application in receivers of frequency-manipulated signals.

The aim of the invention is to improve noise immunity.

The drawing shows a structural electrical circuit of the device.

The device contains an input signal converter 1, a differential detector 2, the first key 3, the limiter 4 at the top at the zero level, the limiter 5 at the bottom at the zero level, the second key 6, the first 7 and the second 8 threshold blocks, AND-HE element 9, the third key 10, an inverter 11 and a registration unit 12, the difference detector 2 comprising a subtracting unit 13 and two channels, each of which consists of a filter 14 and a detector 15

The device works as follows.

In the absence of signals at the input of the input signal converter 1, the keys 3, 6 and 10 are in the closed (initial) state, the second key 6 connecting the signal input to the input of the inverter 11,

The signal and interference received from the ether after passing the converter 1 of the input signal is filtered out by filters of zeros and ones and fed to the inputs of the detectors 15, from the outputs of which the levels of the detected signal are fed to the inputs of the subtraction unit of the difference detector 2.

In the case when the level of the signal from the output of the detector 15 of the second channel exceeds the level of the signal from the output of the detector 15 of the first channel, the output of the subtraction unit 13 is a negative voltage that goes to the inputs of the limiters 4 and 5, while the output of the limiter 4 is at the top level at zero the signal is present, and the output of the limiter 5 from the bottom at the zero level is absent. The first key 3, the impact of the control signal from the output of the limiter 4 on top of the zero level, opens, and the third key 10 remains in a closed state, and the signal from the output of the second channel detector 15 is fed to the input of the first threshold unit 7, where The presence of a signal in a channel by comparison with a threshold voltage.

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In the absence of a signal in the channel in question, there is no signal at the output of the first threshold block 7. Thus, the inputs of the NAND 9 element from the outputs of the threshold blocks 7 and 8 do not receive signals, the output signal of the NAND 9 element receives a control signal to the first input of the second key 6, which leads to its triggering and connecting the output of the subtraction unit 13 directly to the input block

12 registrations that capture a negative premise, i.e. the signal is in the channel where interference is present.

When surrounding the signal in the channel in question, a signal is present at the output of the first threshold block 7, and no signal is output at the output of the second threshold block 8, since the first key 3 is open. There is no signal at the first input of the NAND 9 element, and there is no signal at the second input, therefore, there is no signal at the output of the NAND 9 element and the second key 6 returns to its original position, having connected the output of the block

13 is read to block 12 of registration through an inverter 11; In block 12 of registration a positive scattering is fixed.

In the case when the signal level from the output of the detector 15 of the second channel is less than the signal level at the output of the detector 15 of the first channel, the algorithm of the device operation is similar to “

In the absence of signals at the outputs of the detectors 15 at the output of the subtraction unit 13, there is no signal, therefore the keys 3 and 10 remain in the initial position. At the same time, there are no signals at the inputs of the NANDI element 9, therefore the output of the element 9 contains a signal that opens the second key 6 In this case, the output of the subtraction unit 13 is connected directly to the registration unit 12, which records the absence of any signal.

In the case when only a useful signal is present in the channel, the device receives this signal, considering it to be an interference.

Thus, in the device, the channel is switched off with strong interference and the signal is detected in another channel, while the absence of a signal in the connected channel indicates that there is interference

presence of signal in

Claims (1)

Invention Formula A device for receiving frequency-manipulated signals, containing a first threshold unit, a parcel registration unit and an input signal converter connected in series, and a differential detector containing a subtraction unit and two channels, each of which consists of a series-connected filter and detector, with the outputs of the first and second detectors The second channels are connected to the inputs of the subtraction unit and are, respectively, the first and second outputs of the differential detector, the third output and input of which are respectively Twain output subtracting unit, and the combined filters of both channels inputs otlichayuschee3664 ten 15 20 so that, in order to improve noise immunity, the series-connected limiters from above at the zero level, the first key, the second threshold unit, the NAND element, the second key and the inverter, as well as the serial connection, are introduced into it. The bottom limiter is at the zero level and the third key, the output of which is connected to the input of the first threshold unit, the output of which is connected to the second input of the NAND element, the first, second and third outputs of the differential detector are connected respectively to the second input of the first key, the second input of the third key and the top of the limiter input is at the zero level, the input of which is also connected to the input of the limiter from below and the second input of the second key, the second output of which is connected to the output of the inverter and the input of the unit for recording the topping.