RU187262U1 - Shortwave Preselector - Google Patents

Abstract

The proposed technical solution relates to radio engineering, namely to multi-channel communication systems in the short wavelength range, and can be used to organize radio communications in stationary and moving objects. The technical result is to improve the selectivity while maintaining the high sensitivity of the preselector. To achieve a technical result, the first key (1.1), the second (1.2) and third (1.3) keys, the second attenuator (ATT) 5, the fourth (1.4), and the fourth (1.4) are introduced into the device containing the first group of M band-pass filters (2.1) fifth (1.5) keys, the second group of M band-pass filters (2.2), the output of which is the output of the device. Moreover, the second output of the second key (1.2) is connected through a series-connected first ATT (3) and the first amplifier with controlled amplification (VUU) 4 to the second input of the third key (1.3). The second output of the fourth key (1.4) through the second UUU (6) is connected to the second input of the fifth key (1.5). The first input of the first key (1.1) is connected to the receiving antenna and is a signal, and the second is a calibration input. In addition, blocks 1.1, 1.2, 1.3, 1.4, 1.5, 2.1, 2.2, 3, 4, 5, 6 have control inputs. 3 ill.

Description

The utility model relates to radio engineering, namely to multi-channel communication systems in the short-wave range, and can be used to organize radio communications in stationary and moving objects.

Known filter according to patent [1], which is made on the basis of band-pass filters connected in series. The disadvantage of this analogue is the inability to simultaneously process signals at different frequencies. In addition, devices are described in the information sources [2] and [3].

A disadvantage of the known devices is the poor selectivity of the device, and there is no possibility of simultaneous processing of signals at different frequencies.

The closest analogue in technical essence to the proposed is the device according to the patent of the Russian Federation 2396704, H03H 7/46, adopted as a prototype.

In FIG. 1 shows a structural diagram of a prototype device, which introduced the following notation:

2.1 - a group of M band-pass filters (GPF _M );

2.2 - a group of N bandpass filters (GPF _N );

8 - differential system (DS);

10 - differential transformer (DT);

11 - balanced resistor (BR);

12 - inductor (CI).

In FIG. 2 shows an enlarged structural diagram of a prototype device, where the following notation is introduced:

2.1 - a group of M band-pass filters (GPF _M );

2.2 - a group of N bandpass filters (GPF _N );

8 - differential system (DS).

The prototype device contains a differential system 8, which has two outputs, which are the input of the filtering blocks. A group of N bandpass filters 2.2 is connected to the first output of the differential system, a group of M bandpass filters 2.1 is connected to the second output of the differential system, the outputs of the bandpass filters are the outputs of the filtering unit.

The prototype device works as follows.

Differential system 8 (as shown in the source of information [2]) provides an “isolation” of two groups of bandpass filters connected in parallel at the input. In this case, the implemented differential system 8 introduces an additional attenuation of approximately equal to 5-6 dB. In addition, each of the band-pass filters has an insertion attenuation of 2 to 3 dB, and sometimes more, depending on the requirements for its frequency response. This parameter will be especially critical with relative bandwidths of 3–5%.

Thus, the first group of filters is matched with the load in a real circuit when the filters of the second group have capacitance at frequencies close to the middle frequencies of the first group.

The disadvantage of the prototype device is the poor selectivity of the system, because the prototype device in groups of M and N band-pass filters for each frequency subband has one filter. But this is not enough to achieve the required selectivity, since this is due to the inability to realize the necessary form of the amplitude-frequency characteristic without increasing the filter order [4]. At the same time, increasing the order of the filter leads to a large attenuation in the passband, which degrades the sensitivity of the system.

The objective of the proposed device is to improve selectivity while maintaining high sensitivity preselector.

To solve this problem, a short-wavelength preselector containing two groups of band-pass filters, the first consisting of M band-pass filters, according to a utility model, the second and third keys are connected in series, the second attenuator, the fourth and fifth keys and the second group of M band-pass filters, the output of which is the output of the preselector, in addition, the second output of the second key is connected through a series-connected first attenuator and a first amplifier with controlled amplification to the second input this key, the second output of the fourth key through the second amplifier with controlled amplification is connected to the second input of the fifth key; the output of the first key is connected to the input of the first group of M band-pass filters, the output of which is connected to the input of the second key; the first and second inputs of the first key are signal and calibration, respectively, while the control inputs of all keys, the first and second attenuators, amplifiers with controlled gain and the first and second groups of M band-pass filters are inputs for control signals.

In FIG. 3 shows a structural diagram of the proposed device, where the following notation is introduced:

1.1, 1.2, 1.3, 1.4, 1.5 - the first to fifth keys (K);

2.1, 2.2 - the first and second groups of M band-pass filters (GPF _M );

3, 5 - the first and second attenuators (ATT);

4, 6 - the first and second amplifier with controlled amplification (UUU).

The proposed shortwave preselector contains in series the first key 1.1, the first group of M band-pass filters 2.1, the second 1.2 and third 1.3 keys, the second ATT 5, the fourth 1.4 and fifth 1.5 keys, the second group of M band-pass filters 2.2, the output of which is the output of the device . Moreover, the second output of the second key 1.2 through a series-connected first ATT 3 and the first UUU 4 is connected to the second input of the third key 1.3. The second output of the fourth key 1.4 through the second UUU 6 is connected to the second input of the fifth key 1.5. The control inputs of blocks 1.1, 1.2, 1.3, 1.4, 1.5, 2.1, 2.2, 3, 4, 5, 6 are connected to the corresponding outputs of the processor (not shown in Fig.). The first input of the first key 1.1 is connected to the receiving antenna and is a signal input, and the second input is a calibration one.

The proposed device operates as follows.

In the first key 1.1, there is a switch between the signal coming from the antenna (operating mode) and the calibration signal supplied to another input of the first key 1.1, and the switch is controlled by the signal from the corresponding processor output. When switching to calibration mode, the device parameters are set. Adjustment of the device parameters is carried out in case the amplitude-frequency characteristic (AFC) of the device does not correspond to the required one. Frequency response of the first and second groups of M band-pass filters when combined at the output of the preselector should provide good selectivity. In operating mode, the device operates as follows. The signal from the output of the first key 1.1 goes to the input of the first group of M band-pass filters 2.1, in which, under the control of the processor, there is a switch between M-band filters tuned to different bandwidths, where the noise and side components of the signal are filtered. Then, from the output of the first group of M band-pass filters 2.1, the filtered signal is fed to the input of the second key 1.2, through which it is transmitted either to the first input of the third key 1.3, or through the first attenuator 3 and the first amplifier with controlled amplification 4 connected in series, to the second input of the third key 1.3. The first attenuator 3 and the first amplifier with controlled gain 4 control the level of the incoming signal from the second output of the second key 1.2. The operation of the second 1.2 and third 1.3 keys is controlled by the signals received at the control inputs of the keys from the corresponding outputs of the processor. If the signal satisfies the requirements of the shortwave preselector (the signal must be recognizable and should not overload the second UUU 6), then the signal from the first output of the second key 1.2 goes to the first input of the third key 1.3. If the signal does not meet the requirements of the shortwave preselector (the signal is not recognizable and overloads the second UUU 6), then from the second output of the second key 1.2, the signal is fed to the input of the first attenuator 3, the output of which is connected to the input of the first amplifier with controlled amplification 4, where, under the control of the signals received from the processor, the level of the received signal is adjusted. The level of the incoming signal is adjusted if the signal is not recognized by the system or overloads the second UUU 6. From the output of the third key 1.3, the signal is fed to the input of the second attenuator 5, controlled by the processor, in which, if necessary, weakening of the received signal is possible to prevent overloading of the subsequent second amplifier with controlled gain 6. Then, from the output of the second ATT 5, the signal is fed to the input of the fourth key 1.4, through which the signal is transmitted either to the input of the second amplifier 6, and then to the second input about key 1.5, or at the first input of the fifth key 1.5. The operation of the fourth 1.4 and fifth fifth keys is controlled by the signals received at the control inputs of the keys from the corresponding outputs of the processor. If the signal meets the requirements of the shortwave preselector, then the first output of the fourth key 1.4 is connected to the input of the fifth 1.5. If the signal does not meet the requirements of the shortwave preselector, then from the second output of the fourth key 1.4, the signal is fed to the input of the second amplifier 6, where, under the control of the processor, the level of the incoming signal increases. From the output of the second UUU 6, the signal goes to the fifth key 1.5. From the output of the fifth key 1.5, the signal enters the input of the second group of M bandpass filters 2.2, in which, under the control of the processor, switching between bandpass filters tuned to different passbands occurs, where the second-order intermodulation product is filtered. Switching between bandpass filters in 2.1 and 2.2 occurs in parallel, due to which there are no switching delays between filters. Moreover, each of the filters is tuned to its own frequency range and each band-pass filter from 2.1 has a corresponding one in 2.2, but with a different frequency response form.

Thus, through the use of two groups of M band-pass filters connected in series through elements that control the level of the received signal, such as UUU and ATT, the first group of M band-pass filters 2.1 is the main selection filter, and the second group 2.2 serves to filter the intermodulation product second order. The output of the device is the addition of the frequency response of the corresponding bandpass filters of each of the sub-bands. This is equivalent to increasing the order of the band-pass filter of each of the sub-bands of the preselector, which leads to improved selectivity without compromising the sensitivity of the device.

Peregrine Semiconductor PE42540E-Z key can be used as keys. Groups of M band-pass filters can be constructed according to the standard scheme of this type of filter, for example, using Coilcraft inductor coils and Murata series GRM capacitors. As attenuators, it is possible to use the Peregrine Semiconductor PE43704MLCA-Z chip. As an amplifier with controlled amplification, the use of the Linear Technology LT5514EFE chip is possible. As a processor, it is possible to use, for example, microchips from ATMEL ATSAM4S16BA-AU.

Information sources

1. Patent US4731877, H04N 1/16.

2. Barefoot N.D. Electric filters. Gostekhizdat of the Ukrainian SSR, Kiev, 1957, p. 338.

3. Pleshkov N.E., Zingerenko A.M., Lavrish B.C., Klimovich V.F., Isakson B.K., Long-distance communication technology. Ed. VKAS, Leningrad, 1951, pp. 101-105.

4. Baskakov SI, Radio / technical circuits and signals. Ed. Higher School, Moscow, 2003, pp. 338-347.

Claims (1)

A short-wavelength preselector containing two groups of band-pass filters, the first consisting of M band-pass filters, characterized in that the second and third keys, the second attenuator, the fourth and fifth keys and the second group of M band-pass filters, the output of which is the output of the preselector, are connected in series in addition, the second output of the second key through the first attenuator and the first amplifier with controlled gain connected in series is connected to the second input of the third key, the second output of the fourth Lyucha through a second amplifier with a controllable gain is connected to the second input of the fifth key; the output of the first key is connected to the input of the first group of M band-pass filters, the output of which is connected to the input of the second key; the first and second inputs of the first key are signal and calibration, respectively, while the control inputs of all keys, the first and second attenuators, amplifiers with controlled gain and the first and second groups of M band-pass filters are inputs for control signals.

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