RU2683023C1 - Radio channel imitator - Google Patents

Abstract

FIELD: radio engineering and communications.SUBSTANCE: invention relates to the field of radio engineering and can be used for testing receiving and transmitting devices and modeling a radio channel. Radio channel simulator contains, among other things, noise-like signal driver (NSD) (5), p fixed attenuators (15), t second switches (12), t third adders connected in adders (13) and t second splitters (14), outputs which are connected to the inputs of the corresponding output controlled attenuators (9.1–9.k), while the other inputs t of third adders (13) are connected to the corresponding outputs of the first splitter (8), the other outputs t of second switches (12) are connected to the corresponding inputs of second adder (7), and the inputs t of second keys (12) are connected to the outputs of DAC (6) from the second to s, respectively, however, the outputs of DAC (6) from the first to the p are connected to the inputs of p fixed attenuators (15), respectively. In addition, input control inputs (1.1…1.N) and outputs (9.1…9.k) controlled attenuators, first (10) and second (12.1…12.t) keys, as well as NSD (5) are connected to the control bus.EFFECT: expanding the functionality of the simulator by creating a variety of environmental conditions during the propagation of the radio signal.5 cl, 8 dwg

Description

The proposed device relates to the field of radio engineering: for testing receiving and transmitting devices and specifically to the issues of modeling a radio channel.

Known radio channel simulators containing in their structure a simulator of multipath propagation, a simulator of the Doppler effect, a simulator of signal attenuation. So, in the application US 20030088390 dated 05/08/2003, a multipath propagation simulator is considered, but it has a drawback - it is limited to one type of simulated influence and does not have the ability to simulate other effects on a useful signal during propagation in the atmosphere; the high-frequency channel simulator according to patent US 6058261 dated 2.05.2000, the disadvantage of which is that it can only be used to simulate multipath propagation and only with certain delays, i.e. has limited functionality.

The closest analogue in technical essence to the proposed one is the simulator UKVRadiokanalapo according to patent No. 175192 of 05/02/2017.

The block diagram of the prototype device is shown in FIG. 1, where the following notation is introduced:

1.1 ... 1.N - input controlled attenuators;

2 - analog-to-digital converter (ADC);

3, 7 - the first and second adders;

4 - channel simulator with multipath propagation (PCM);

- цифровые генераторы шума (ЦГШ);

- digital noise generators (TsGSh);

6.1 ... 6s - digital-to-analog converters (DAC);

8 - splitter;

9.1 ... 9.k - output controlled attenuators;

10 is the key.

The prototype device contains a serially connected input controlled attenuator 1.1, key 10, ADC 2, PCM 4, DAC 6.1, a second adder 7 and a splitter 8, k outputs of which are connected to the inputs of the corresponding output attenuators 9.1 ... 9.k, the outputs of which are k outputs devices. The outputs of the input controlled attenuators 1.2 ... 1.N are connected to the corresponding inputs of the first adder 3, the output of which is connected to the corresponding input of the second adder 7. In addition, the output of each DSS from 5.1.1 to 5.mi is connected to the input of each from 6.2 to 6. s are the DACs, respectively, whose outputs are connected to the corresponding inputs of the second adder 7. The second inputs of the ADC 2, PCM 4 and DAC 6.1 ... 6.s and the inputs of the DCH 5.1.1 ... 5.mi are inputs for clock pulses f ₀ . The second output of the key 10 is connected to the corresponding input of the first adder 3. The inputs of the input controlled attenuators 1.1 ... 1.N are N inputs of the device.

The prototype device operates as follows.

The signal from the external device is fed to an input controlled attenuator 1.1, the structure of which includes a fixed attenuator and a tunable attenuator (not shown in Fig. 1). Thus, the overall signal attenuation range is from 40 dB to 100 dB. Using a fixed attenuator prevents the occurrence of such unwanted distortions of the input signal, such as limiting the input signal level (blocking) and intermodulation. The signal from the output of the controlled attenuator 1.1 enters the key input into two positions 10, and depending on the key position, the signal can go either to the first output of the key and then to the input of the ADC 2, or to the second output of the key and then to the input of the adder 3. С the output of the ADC 2 is already a digital signal is fed to the input of PCM 4. The signal from the output of PCM 4 is fed to the DAC 6.1, the output of which is fed to the corresponding input of the adder 7. In parallel to the PCM 4 are included TsGSh 5.1.1 ... 5.mi As TsGSh5.1.1 ... 5.mi, you can use, for example, a signal generator with linear frequency modulation (LFM), due to the fact that the form of the spectral power density and the autocorrelation function of the signal with linear frequency modulation are similar to those of a limited band white gaussian noise. In addition, the formation of other types of noise is possible in TsGSh 5. The generated noise signals are fed to the inputs of the DAC 6.2 ... 6.s, and the received analog signals are fed to the inputs of the second adder 7.

From the inputs 2 ... N, through the corresponding controlled attenuators 1.2 ... 1.N, the signals are fed to the inputs of the first adder 3 and then the corresponding input of the second adder 7, from the output of which the total signal is fed to the input of the splitter 8, where it is divided into the required number of k channels. These signals from the outputs of the splitter 8 through the output controlled attenuators 9.1 ... 9.k, (similar to the work of the input attenuators, only with a attenuation coefficient from 0 to 60 dB), are fed to the corresponding outputs of the device.

The disadvantages of the prototype device is that the interference at all outputs of the device have the same characteristics, which leads to the limitation of the use of such a simulator.

The objective of the proposed device is the expansion of functionality by providing interference on different groups of outputs with different parameters.

To solve the problem in a radio channel simulator containing N input controlled attenuators, the output of the first of which is connected through the first key to the input of an analog-to-digital converter (ADC); the outputs from the second to N input controlled attenuators are connected to the corresponding inputs of the first adder, the output of which is connected to the corresponding input of the second adder, the output of which is connected to the input of the first splitter, as well as m digital-to-analog converters (DACs) and k output controlled attenuators, the outputs of which are respective outputs of the device, in addition, the second inputs of the ADC and DAC are inputs for clock f _0, according to the invention introduced noise-shaper signal (FNS) in od which is connected to the ADC output, the other input is the input for clock pulses f _0, FNS outputs connected to inputs of the DAC, respectively, and p fixed attenuators whose outputs are connected to respective second adder inputs, the input of each of a number of fixed attenuator connected to the output of the corresponding DAC from the first to p; t second keys, the first outputs of which are connected to the corresponding inputs of the second adder, the input of each of the second keys is connected to the input of the DAC from (p + 1) to m, respectively, in addition, t of the third adders whose outputs are connected to the inputs of t of the second splitters, respectively moreover, the first inputs of the third adders are connected to the corresponding outputs of the first splitter, and the second to the second outputs of the second keys, respectively; the outputs t of the second splitters are connected to the inputs k of the output controlled attenuators, respectively; the control bus is connected to the control inputs of N input controlled attenuators, first and second keys, k output controlled attenuators and a noise-former.

The task is achieved by a combination of analog and digital forms of processing a radio signal.

The list of figures explaining the description of the device: FIG. 1 is a block diagram of a prototype device; FIG. 2 is a block diagram of the proposed device; FIG. 3 is a block diagram of a shaper of noise-like signals; FIG. 4 is a block diagram of a shaper of band-limited quasi-Gaussian noise; FIG. 5 is a block diagram of a chirp signal generator; FIG. 6 - signal from the output of the sawtooth signal generator with a pseudo-random frequency; FIG. 7 - power spectral density of a band-limited quasi-Gaussian noise at a center frequency of 30 MHz with a band of 3000 kHz; FIG. 8 - spectral power density of the chirp signal at a center frequency of 30 MHz with a band of 3000 kHz.

A diagram of the proposed device is shown in FIG. 2, where indicated:

1.1 ... 1.N - input controlled attenuators;

2 - analog-to-digital converter (ADC);

3, 7 - the first and second adders;

5 - shaper noise-like signals (FSH);

6.1 ... 6.m - digital-to-analog converters (DAC);

8 - the first splitter;

9.1 ... 9.k - output controlled attenuators;

10 - the first key;

11 - control bus (ШУ);

12.1 ... 12.t - second keys;

13.1 ... 13.t - third adders;

14.1 ... 14.t - second splitters;

15.1 ... 15.r - fixed attenuators.

A block diagram of a noise-like signal former is shown in FIG. 3, where indicated:

4 - channel simulator with multipath propagation and the Doppler effect (ICMD);

5.1 ... 5.m - m groups of digital noise generators (TsGSh);

5.1.1 ... 5.1.i, 5.2.1 ... 5.2.j, 5m.1 ... 5.m.b - digital noise generators;

11 - control bus;

16.1 ... 16.m - digital adders;

17 is a digital key.

The proposed device contains a series-connected input controlled attenuator 1.1, the first key 10, ADC 2 and FSH 5, the outputs of which are connected to the inputs of the corresponding DAC 6.1 ... 6.m. The outputs of the first group of DACs from 6.1 to 6.p through the corresponding fixed attenuators 15.1 ... 15.p are connected to the corresponding inputs of the second adder 7. The outputs of the second group of DACs from 6. (p + 1) to 6.m are connected to the inputs of the second keys 12.1 ... 12.t, the first outputs of which are connected to the corresponding inputs of the second adder 7, and the second outputs - to the inputs of the corresponding third adders 13.1 ... 13.t, the outputs of which are connected to the inputs of the corresponding second splitters 14.1 ... 14.t, the outputs of which are connected to the inputs corresponding output attenuators 9.1 ... 9.k, the outputs of which are k outputs of the device. The output of the second adder 7 is connected to the input of the first splitter 8, the outputs of which are connected to the corresponding inputs of the third adders 13.1 ... 13.t. In addition, the second inputs of the ADC 2, FSH 5 and DAC 6.1 ... 6.m are inputs for clock pulses f ₀ . Moreover, the control bus 11 is connected to the control inputs of the input and output controlled attenuators 1.1 ... 1.N and 9.1 ... 9k, the first 10 and second 12.1 ... 12.t keys, as well as FShS 5.

The noise-like signal shaper 5 (Fig. 3) contains a channel simulator with multipath propagation and the Doppler effect (ICMD) 4 and a digital key 17, the output of which is the first output of the FShS 5, as well as m groups of digital noise generators (TsGSh) 5.1 ... 5 .m, each of which contains ЦГШ 5.1.1 ... 5.1.i, 5.2.1 ... 5.2.i, 5.m.1 ... 5.mi, (the number of which may be different in each group), the outputs of which are connected to the corresponding the inputs of the respective digital adders 16.1 ... 16.m. The output of the first adder 16.1 is connected to the corresponding input of the digital adder 17. The outputs of the digital adders from second to m 16.2 ... 16.m are the corresponding FSH outputs 5. In addition, the FSH input for clock pulses f _{0 is} connected to the combined corresponding inputs of the ICMD 4 and TsGSh5.1.1 ... 5.1.i, 5.2.1 ... 5.2.j, 5.m.1 ... 5.mb, the control inputs of which are connected by the control bus 11, which is connected to the control input of the digital key 17 and connected to the control input of FShS 5 .

The inventive device operates as follows.

The signal from the external device is fed to an input controlled attenuator 1.1, the structure of which includes a fixed attenuator and a tunable attenuator (not shown in Fig. 2). Using a fixed attenuator prevents the occurrence of such unwanted distortions of the input signal, such as limiting the input signal level (blocking) and intermodulation. The signal from the output of the controlled attenuator 1.1 enters the key input into two positions 10, and depending on the position of the key 10, the signal can then go either to the first output of the key and then to the input of the ADC 2, or to the second output of the key and then to the input of the first adder 3 From the output of the ADC 2, the digital signal is already fed to the input of the noise-like signal shaper (FSH) 5, from the outputs of which noise-like signals are fed to the corresponding inputs of the DAC 6.1 ... 6.m. Then, the output signals of the first group of DACs from 6.1 to 6.p through fixed attenuators 15.1 ... 15.p (such attenuators can be from 1 to p) are fed to the corresponding inputs of the second adder 7. Output signals of the second group of DACs from 6. (p + 1 ) through 6.m through the second keys 12.1 ... 12.t (there can be from 1 to t such keys) either to the corresponding inputs of the second adder 7, or to the corresponding inputs of the third adders 13.1 ... 13.t, depending on the position of the second keys 12.1 ... 12.t. The total signal from the output of the second adder 7 is fed to the input of the first splitter 8, from the t outputs of which the signals are fed to the corresponding inputs of the third adders 13.1 ... 13.t and then through the second splitters 14.1 ... 14.t to the output controlled attenuators 9.1 ... 9.k, (similar to the work of input attenuators), from the outputs of which they go to the corresponding outputs of the device.

From the inputs 2 ... N of the simulator through the corresponding controlled attenuators 1.2 ... 1.N the signal through the first adder 3 is fed to the corresponding input of the second adder 7.

On the control bus 11, control signals are supplied to the control inputs of input 1.1 ... 1.N and output 9.1 ... 9.k of controlled attenuators, first 10 and second 12.1 ... .12.t keys, as well as FSh 5.

As digital noise generators 5.1.1 ... 5.1.i, 5.2.1 ... 5.2.j, 5.m.1 ... 5.m.b, you can use, for example, a band-limited quasi-Gaussian noise generator or an LFM signal generator.

Examples of the construction of these generators may be as shown in FIG. 4 and 5.

In FIG. 4 shows a block diagram of a generator of band-limited quasi-Gaussian noise, where it is indicated: 19.1, 19.2 - generator of a pseudo-random M-sequence; 20.1, 20.2 - tunable filter with infinite impulse response; 21.1, 21.2 - filter corrector with finite impulse response; 22.1, 22.2 - interpolator with a variable interpolation coefficient; 23 - direct digital synthesis synthesizer; 24.1, 24.2 - mixer; 25 - adder.

A band-limited quasi-Gaussian noise generator contains two parallel rulers, each of which contains a pseudo-random M-sequence generator 19.1 (19.2) connected in series, a tunable filter with an infinite impulse response 20.1, (20.2), a filter corrector with a finite impulse response 21.1, (21.2 ), the interpolator with a variable interpolation coefficient 22.1, (22.2), a mixer 24.1, (24.2). The first outputs of the mixers 24.1 and 24.2 are connected to the corresponding inputs of the adder 25, the output of which is the output of the generator. The outputs of the direct digital synthesis synthesizer 23 are connected to the second inputs of the mixers 24.1 and 24.2, respectively.

To form a quasi-Gaussian noise limited in band, signals are initially used in the form of two unequal M-sequences from outputs 19.1 (19.2), since these signals occupy a wide frequency band, then these signals are filtered in tunable low-pass filters (LPFs) 20.1 (20.2), filter corrector 21.1 (21.2) is used to compensate for the non-uniformity of the characteristics of the subsequent interpolation path, and after filtering, a signal is obtained at zero frequency with a uniform spectrum limited in a given band, this signal is interpolated in an interpolator with a variable interpolation coefficient 22.1 (22.2) and transferred to the required high frequency using a circuit consisting of a direct digital synthesizer synthesizer 23, mixers 24.1 (24.2) and an adder 25.

A block diagram of the chirp signal generator is shown in FIG. 5, where it is indicated: 26 - a sawtooth signal generator with a pseudo-random frequency; 27 - a device for scaling; 28 - direct digital synthesis synthesizer. (The signal from the output of the generator 26 is shown in Fig. 6).

The device operates as follows. The sawtooth signal with a pseudo-random frequency from the output of the sawtooth signal former 26 passes through the scaling device 27, after which the sawtooth signal is a frequency code and is fed to the input of the direct digital synthesis synthesizer 28, the output of which is a signal with linear frequency modulation.

Thus, in the FSH 5, the signals shown in FIG. 7 (band-limited quasi-Gaussian noise) and FIG. 8 (chirp signal). In addition, the formation of other types of noise-like signals is possible in the CGS.

The generated noise-like signals in the 5.1.1 ... 5.1.i, 5.2.1 ... 5.2.j, 5.m.1 ... 5.mb generators combined in m groups 5.1 ... 5.m (the values i≥1, j≥ 1, b≥1), received at the inputs of the respective digital adders 16.1 ... 16.m.

As digital noise generators 5.1.1 ... 5.1.i, 5.2.1 ... 5.2.j, 5.m.1 ... 5.m.b, it is possible to use, for example, a band-limited quasi-Gaussian noise generator and / or an LFM signal generator.

The signal from the output of the ADC 2 receives the input FSH 5, which is the input of the ICMD 4, the output of which the signal is fed through the key 17 to the first output of the FSH 5.

The device has several modes of operation.

1. In simplified mode, all N device inputs through input controlled attenuators 1.1 ... 1.N are connected to the first adder 3 (key 10 is switched to the second output), and the second adder 7 receives a signal only from the output of the first adder 3. In this case, it is simulated propagation of signals with attenuation without the intervention of other influences.

2. In addition to the first mode, a noise-like signal shaper 5 can be switched on, from the outputs of which noise-like signals are fed to the DAC inputs 6.2 ... 6.m through the second keys 12.1 ... 12.t and further, if all the key outputs are connected to the corresponding inputs of the second adder 7, this creates a situation of adding a noise-like signal to the useful signal, with each output having noise-like signals with the same characteristics; if the outputs of all the keys are connected to the corresponding inputs of the third adders 13.1 ... 13.t, then a situation also arises when a noise-like signal is added to the useful signal, only in this case at the outputs of each of t third adders 13.1 ... 13.t, and, respectively, at the outputs , the characteristics of noise-like signals will vary. In addition, situations of different positions of the second keys 12.1 ... 12.t are possible, i.e. the outputs of some of them are connected to the corresponding inputs of the second adder 7, and others to the corresponding inputs of the third adders 13 and, therefore, various combinations of the signal-to-noise ratio and characteristics of noise-like signals at different outputs are possible.

3. In the third embodiment, the key 10 switches to the first output, and the signal through the ADC 2 enters the ICMD4. Thus, the simulation mode of multipath signal propagation and / or the Doppler effect is turned on.

As a controlled attenuator, it is possible to use, for example, Peregrine microcircuits. As an ADC, you can use, for example, the 16-bit LTC2208IUP ADC from Linear Technology, and a 14-bit DAC5672IPFB from Texas Instruments as the DAC.

The noise-like signal generator 5 can be made in digital form, for example, based on the Altera chip EP4CE115F23I7N, in which 281 inputs / outputs are provided.

The second keys 12.1 ... 12.t can be implemented on the PE42521MLBA-Z chip, the third adders 13.1 ... 13.t on the ADP-2-1W chip.

The introduction of a simulator of m second keys, a shaper of noise-like signals, m third adders and m second splitters allows you to expand the functionality of the device and provide a wider choice of parameters of the created wireless channel by providing various characteristics of noise-like signals.

Claims (5)

1. A radio channel simulator containing N input controlled attenuators, the output of the first of which is connected through the first key to the input of an analog-to-digital converter (ADC); the outputs from the second to N input controlled attenuators are connected to the corresponding inputs of the first adder, the output of which is connected to the corresponding input of the second adder, the output of which is connected to the input of the first splitter, as well as m digital-to-analog converters (DACs) and k output controlled attenuators, the outputs of which are the corresponding outputs of the device, in addition, the second inputs of the ADC and DAC are inputs for clock pulses f ₀ , characterized in that the driver of noise-like signals (FSH), input One of which is connected to the ADC output, the other input is an input for clock pulses f ₀ , the FSH outputs are connected to the DAC inputs, respectively, as well as p fixed attenuators, the outputs of which are connected to the corresponding inputs of the second adder, while the input of each of the p fixed attenuators is connected to the output of the corresponding DAC from the first to p; t second keys, the first outputs of which are connected to the corresponding inputs of the second adder, the input of each of the second keys is connected to the input of the DAC from (p + 1) to m, respectively, in addition, t of the third adders whose outputs are connected to the inputs of t of the second splitters, respectively moreover, the first inputs of the third adders are connected to the corresponding outputs of the first splitter, and the second to the second outputs of the second keys, respectively; the outputs t of the second splitters are connected to the inputs k of the output controlled attenuators, respectively; the control bus is connected to the control inputs of N input controlled attenuators, first and second keys, k output controlled attenuators and a noise-former. 2. The simulator according to claim 1, characterized in that the noise-like signal generator (FSN) contains a series-connected channel simulator with multipath propagation and the Doppler effect (ICMD) and a digital key, the output of which is the first output of the FSN, as well as m groups of digital noise generators (TsGSh), the outputs of each of which are connected to the corresponding inputs of each of m adders, respectively, while the output of the first adder is connected to one of the inputs of the digital key; the outputs of the adders from the second to m are the corresponding FSH outputs, in addition, the IKDM input is the first FSH input, the input for clock pulses f ₀ combines the inputs for the PCMD clock pulses and each digital noise generator from m groups of digital noise generators; the control inputs of the ICMD, digital noise generators and a digital key are connected by a control bus and are the FSH control input. 3. The simulator according to claim 2, characterized in that the digital noise generators contained in m groups are made in the form of shapers of band-limited quasi-Gaussian noise. 4. The simulator according to claim 2, characterized in that the digital noise generators contained in m groups are made in the form of sawtooth signal generators with a pseudo-random frequency. 5. The simulator according to claim 2, characterized in that the digital noise generators contained in m groups are made both as shapers of band-limited quasi-Gaussian noise and as sawtooth signal generators with a pseudo-random frequency.

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