RU2660660C2 - Radio receiving device with the dither signal amplitude switch control - Google Patents

Abstract

FIELD: radio equipment and communications.

SUBSTANCE: invention relates to radio equipment

and can be used to create promising radio facilities with programmable architecture with digital signal processing directly at the radio frequency under the influence of blocking signals to ensure stable radio communication in complex interference environment. Radio receiving device with dither signal amplitude switch control contains: in series connected input circuits unit and pre-selector, adder, analogue-to-digital converter (ADC), digital receiving path and demodulator, which output is the device information output; in series connected dither signal generator and key, which output is connected to the adder second input; sampling frequency source comprising N reference oscillators, whose outputs are connected to respective switch inputs, which output is the sampling frequency source output and connected to the ADC clock input, as well as in series connected the received signal amplitude calculator, which input is connected to the ADC output, and digital comparator, which output is connected to the key first input.

EFFECT: technical result is increase in the dynamic range by the useful signal blocking while preserving the radio receiving device parameters by selectivity.

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Description

The invention relates to the field of radio engineering and can be used to create promising radio facilities with a programmable architecture with digital signal processing directly at the radio frequency, under the influence of blocking signals to ensure stable radio communication in a difficult jamming environment.

Such receivers are described, for example, in the books Cognitive radio technol-ogy, Second Edition, Elsevier Science & Technology Books, 2009. - p.p. 828, author Bruce Alan Fette and Software Defined Radio: enabling technologies, John Wiley & Sons, Chichester, UK, 2002. - p.p. 442 by W. Tuttlebee, Ed, in which they are called ideal.

The essence of such devices is the implementation of analog-to-digital conversion (ADC) at the radio frequency; the use of blurring signals to increase frequency selectivity; ensuring the maximum magnitude of the received signal at the input of the ADC, which does not lead to a limitation in the analog-to-digital path (ADC), which allows to increase the dynamic range for blocking the useful signal.

In existing analogs [1-4], the digitization error and the temperature drift of the characteristics of the ADC and peak detector are manifested in the non-determinism of the actual input level of the ADC overflow. This leads to the need to set the threshold of the comparator based on the minimum possible during operation of the signal level, causing overflow in the ACC, and, consequently, to reduce the dynamic range for blocking.

Closest to the claimed is the device described in the patent [1], taken as a prototype.

In FIG. 1 shows a functional diagram of a prototype device, where it is indicated:

1 - block input circuits and preselector;

2 - adder;

3 - analog-to-digital Converter (ADC);

4 - digital receiving path;

5 - demodulator;

6 - driver erosion signal;

7 - source of sampling frequency;

8.1-8.N - from the first to the N-th reference generator;

9 - switch;

12 - key;

13 - peak detector;

18 is a comparator.

The prototype device contains a series-connected block of input circuits and preselector 1, adder 2, ADC 3, a digital receiving path 4 and a demodulator 5, the output of which is the information output of the device; and also contains a driver of the erosion signal 6, a sampling frequency source 7, containing N reference generators 8.1 ... 8.N, the outputs of which are connected to the corresponding inputs of the switch 9, the output of which is the output of the sampling frequency source 7 and connected to the clock input of the ADC 3.

In addition, the receiver contains a series-connected peak detector 13, a comparator 18 with a threshold value P1 and a key 12, the output of which is connected to the second input of the adder 2, and the second input of the key 12 is connected to the output of the driver of the erosion signal 6. Also, the output of the input circuit block and preselector 1 is connected to the input of the peak detector 13.

The prototype device operates as follows.

The input RF signal is fed to the input of the radio receiver and passes through the block of input circuits and preselector 1, in which it is amplified and filtered out of interference outside the passband of the preselector. From the output of block 1, the received signal is fed to the first input of adder 2, as well as to the input of the peak detector 13, from the output of which the measured value of the amplitude of the received signal is compared with threshold П1 using the comparator 18. If the amplitude of the received signal exceeds the threshold value, then the key 12 stops the signal from the output of the driver of the additive erosion signal 6 to the second input of the adder 2, if the measured amplitude is less than the threshold value, then the key 12 passes the signal from the output of the driver of the additive about the erosion signal 6 to the second input of the adder 2. From the output of the adder 2, the signal is fed to the signal input of the ADC 3, the clock input of which receives a signal with a sampling frequency. For its formation, the source of sampling frequency 7 includes N reference oscillators 8.1-8.N and a switch 9 that connects the clock input of the ADC 3 to one of them in accordance with the current mode of operation of the ADC 3. The quantized samples of the signal after ADC 3 go to the digital receiving tract 4, where filtering, transferring the signal to zero frequency and decimation are performed to lower the sampling frequency. Further, in the demodulator 5, a decision is made to receive the signal. The received information is sent to the output of the radio receiver.

One of the most important dynamic parameters characterizing the ability of a radio receiver to receive a signal in the presence of large amplitude interference is the dynamic blocking range [5], which is defined as the ratio of the maximum level of radio noise at the input, at which the blocking coefficient is equal to a given value, to the sensitivity of the radio receiver in the absence of interference.

The disadvantage of the prototype device is the narrowing of the dynamic range for blocking the useful signal by reducing the maximum level of the blocking signal, which does not limit the ADC, due to the need to lower the threshold of the comparator by the amount of error caused by the thermal drift of the parameters of the ADC and the comparator itself.

The objective of the invention is the implementation of the control of the amplitude of the erosion signal, regardless of temperature errors and level drift of the input ADC signal, causing overflow.

The technical result achieved is an increase in the dynamic range for blocking the useful signal while maintaining the parameters for the selectivity of the radio receiver.

To solve the problem in a known radio receiving device, comprising: a series-connected block of input circuits and a preselector, an adder, an analog-to-digital converter (ADC), a digital receiving path and a demodulator, the output of which is the information output of the device; serially connected driver of the erosion signal and a key, the output of which is connected to the second input of the adder; a sampling frequency source containing N reference generators whose outputs are connected to the corresponding inputs of the switch, the output of which is the output of the sampling frequency source and connected to the ADC clock input, according to the invention, a series-connected calculator of the received signal amplitude, the input of which is connected to the ADC output, is additionally introduced, and a digital comparator with a threshold value of P2, the output of which is connected to the first input of the key, while the threshold value of P2 is determined by the formula:

,

,

where FS is the instantaneous value of the digital signal corresponding to the maximum input instantaneous voltage that does not cause ADC limitation;

A _d is the amplitude of the erosion signal, V;

.K _ADC - _ADC conversion coefficient, establishing a correspondence between the input voltage of the ADC and its output code,

.

A functional diagram of the inventive receiving device is shown in FIG. 2, where indicated:

1 - block input circuits and preselector;

2 - adder;

3 - analog-to-digital Converter (ADC);

4 - digital receiving path;

5 - demodulator;

6 - driver erosion signal;

7 - source of sampling frequency;

8.1 ... 8.N - from the first to the N-th reference generators;

9 - switch;

10 - calculator of the amplitude of the received signal;

11 - digital comparator;

12 is the key.

The inventive device comprises: series-connected block of input circuits and preselector 1, adder 2, ADC 3, digital receiving path 4 and demodulator 5, the output of which is the information output of the device; serially connected the driver of the erosion signal 6 and the key 12, the output of which is connected to the second input of the adder 2. In addition, the device contains a sampling frequency source 7 containing N reference generators 8.1-8.N, the outputs of which are connected to the corresponding N inputs of the switch 9, the output which is the output of the sampling frequency source 7 and is connected to the clock input of the ADC 3, the output of which is connected through a series-connected calculator of the amplitude of the received signal 10 and the digital comparator 11 to the first input house key 12.

The inventive device operates as follows.

The input RF signal is fed to the input of the radio receiver and passes through the block of input circuits and preselector 1, in which its amplification and filtering of interference outside the preselector passband occur. From the output of block 1, the received signal is fed to the first input of adder 2, where it is added to the additive erosion signal supplied through key 12, which is generated in block 6.

From the output of the adder 2, the signal is fed to the signal input of the ADC 3, the clock input of which receives a signal with a sampling frequency. For its formation, the source of sampling frequency 7 includes N reference oscillators 8.1-8.N and a switch 9 that connects the clock input of the ADC 3 to one of these generators, in accordance with the current mode of operation of the ADC 3. The quantized samples of the signal after ADC 3 are received the digital receiving path 4, as well as to the input of the calculator of the amplitude of the received signal 10, from the output of which the measured value of the amplitude of the received signal is fed to the input of the digital comparator 11, where the amplitude of the received signal is compared with the horn value of P2 of this comparator. If the amplitude of the received signal exceeds the threshold value P2, then the key 12 stops the erosion signal from the output of block 6 to the second input of the adder 2, if the measured amplitude is less than the threshold value P2, then the key 12 passes the erosion signal from the output of block 6 to the second input of the adder 2 In the digital receiving path 4, filtering, transferring the signal to zero frequency and decimation is carried out to lower the sampling frequency. Further, in the demodulator 5, a decision is made to receive the signal. The received information is sent to the output of the radio receiver.

The undoubted advantages of such an implementation of the device include the absence of the influence of the ADC 3 overflow level drift on the decision to turn off the erosion signal, regardless of the operating temperature, since the amplitude estimation and comparison with the threshold are performed in digital form. This allows you to increase the maximum unlimited level of the blocking signal by strictly specifying the maximum possible threshold for turning off the erosion signal. The frequency selectivity, for which the erosion signal is used in the prototype device, also does not change, because at high levels exceeding the response threshold P2 of the digital comparator 11, the blocking signal provides a decrease in the correlation between the signal and the products arising due to the nonlinearity of the amplitude characteristic of the ACC, and a fading signal for the received signal.

The implementation of blocks 1-9 and 12 of the claimed receiving device is similar to the blocks of the prototype device and can be performed in accordance with the monograph by Paul Horowitz and Winfield Hill “The Art of Circuit Engineering” in 2 volumes. Moscow, World, 1986

The implementation of block 11 is known and also described in the monograph by Paul Horowitz and Winfield Hill “The Art of Circuit Engineering” in 2 volumes. Volume 1. Moscow, World, 1986, pp. 534-535.

Block 10 is designed to evaluate the digital code A at the ADC output corresponding to the instantaneous amplitude of the received signal by calculating the absolute value of the current samples S of the received signal, which in the general case can be calculated by the formula:

^,

^,

where S is the digital code of the current count of the received signal;

- цифровой код, соответствующий мгновенной амплитуде принимаемого сигнала;

- a digital code corresponding to the instantaneous amplitude of the received signal;

- поразрядно инвертированное значение цифрового кода текущего отсчета принимаемого сигнала.

- bitwise inverted value of the digital code of the current count of the received signal.

The implementation of block 10 is a common engineering task and can be performed, for example, in accordance with the algorithm shown in FIG. 3.

From the output of the ADC 3, the samples of the received signal are fed to block 14, where the current sample of the received signal is stored in the variable S to evaluate the module. Further, for this, in block 15, the sign of the current reference is determined by comparing the value of the variable S with zero.

If condition S≥0 is fulfilled, then the stored value determines the instantaneous value A of the amplitude of the received signal, which is supplied to the output of block 10.

, а затем это значение увеличивается на единицу.If the condition S≥0 is not fulfilled, then in accordance with the principle of calculating the opposite number in the additional code in block 16, a bitwise inversion of the values of S is performed, we obtain

and then this value increases by one.

In this case, at the output of block 10, we have:

A = S ₁ +1.

Next, the obtained value of A is fed to block 11.

Here is a proof of the effectiveness of the claimed device.

The value of the dynamic range for blocking is defined as the ratio of the maximum level of radio noise at the input, at which the blocking coefficient is equal to a given value, to the sensitivity of the radio receiver in the absence of interference.

To increase the dynamic range, the task was defined as ensuring the maximum magnitude of the received signal at the ADC input, which does not lead to a limitation in the ADC, regardless of the drift of the ADC overflow level.

In accordance with the objective, a radio receiving device was implemented in which to receive a mixture of a useful signal and blocking noise, the full range of ADC input signals that do not cause overflow was provided, regardless of the amplitude of the erosion signal and the temperature mode of the device.

To ensure maximum dynamic range in the prototype device, the maximum swing of the received signal at the input of the ADC is supported, which does not lead to a limitation in the ADC. For this, key control of the amplitude of the scattering signal is implemented based on a comparison of the amplitude of the input signal with a hard-set threshold P1 in comparator 18. With this implementation, there is always a digitization error and temperature drift of the characteristics of the ADC and peak detector, which manifest themselves in a dynamic change in the level of the ADC overflow, which at a fixed threshold level of the comparator can lead to overflow in the ACC. This leads to the need to take this effect into account by reducing the threshold of the comparator by the amount of error, which leads to a narrowing of the dynamic range.

The threshold value P1 in the comparator 18 of the prototype device is determined:

P1 = A _max -A _d -ξ,

where A _max - the maximum amplitude of the signal at the input of the ADC, V;

A _d is the amplitude of the erosion signal, V;

ξ is the total digitization error, V.

Therefore, in the prototype, to quantify the increase in the dynamic range of the radio receiver, it is necessary to evaluate the total error of the main temperature-dependent and time-dependent characteristics of the ADC (zero offset and change in the slope of the conversion characteristic) and comparator (zero offset).

, что позволяет обеспечить максимальный динамический диапазон независимо от температурного режима работы приемного устройства и амплитуды размывающего сигнала.When the blocks 10 and 11 are introduced into the receiving device, we obtain that the threshold value P2 of the digital comparator 11, in comparison with the value of P1 (the comparator in the prototype), can be increased by

that allows you to provide maximum dynamic range regardless of the temperature of the receiving device and the amplitude of the erosion signal.

Thus, in the inventive device, the threshold value P2 of the digital comparator 11 is determined:

,

,

where FS is the instantaneous value of the digital signal corresponding to the maximum input instantaneous voltage that does not cause ADC limitation;

A _d is the amplitude of the erosion signal, V;

.K _ADC - _ADC conversion coefficient, establishing a correspondence between the input voltage of the ADC and its output code,

.

In the particular case, for example, the AD9626 ADC chip has a bias error of 4 mV, a gain error of 1.4 mV, a zero offset of ± 8 μV / ° C, and a change in the slope of the conversion characteristic of 0.021% / ° C. Then the value of the digitization error of the received signal ξ at an ADC overflow level of 1.25 V, a 12-bit quantization resolution and a temperature range from minus 40 ° C to 85 ° C will be:

ξ = 4⋅10 ^-3 + 1.4⋅10 ^-3 + 125⋅0.021⋅1.25⋅10 ^-2 + 8⋅10 ^-6 ⋅125≈40 mV

по сравнению с прототипом, при этом достигается увеличение динамического диапазона по блокированию независимо от температурного режима.Then, in this particular case, in the inventive radio receiver, the amplitude of the blocking interference, which does not lead to an overflow of the ADC, can be increased by

compared with the prototype, while achieving an increase in the dynamic range of blocking regardless of the temperature regime.

This allows you to digitally evaluate the amplitude of the signal and compare it with a threshold value, regardless of the drift of the ADC overflow level.

Therefore, the inventive radio receiver device provides an additional extension of the dynamic range for blocking to ensure stable radio communication in a difficult jamming environment.

Literature

1. RF patent for the invention No. 2548658. A radio receiver with key control of the amplitude of the erosion signal. - Makoviy B.A., Shkurov S.A., Ermakov S.A. IPC Н04В 1/64 - 8 pp., Registration 03.10.2013. - Publ. 04/20/15, Bull. No. 11.

2. US Patent No. 6268814, publ. 07/31/2001.

3. Makovy V.A., Ermakov S.A. Extension of the frequency range of analog-digital paths by digital correction // Theory and technique of radio communications. - 2013. - No. 3. - S. 59-66.

4. Makovy V.A. Digital correction of combinations in SDR radio stations // Theory and technique of radio communication. - 2012. - No. 3. - S. 25-34.

5. GOST 24375-80. Radio communication. Terms and Definitions. - M .: Publishing house of standards, 1987. - 58 p.

6. Makovy V.A. Calculation of the analog-digital path of software-defined radio facilities // Theory and technique of radio communication. - 2010. - No. 2. - C. 65-73.

Claims (1)

A radio receiver with key control of the amplitude of the erosion signal, comprising a series-connected block of input circuits and a preselector, an adder, an analog-to-digital converter (ADC), a digital receiving path and a demodulator, the output of which is the information output of the device; serially connected driver of the erosion signal and a key, the output of which is connected to the second input of the adder; a sampling frequency source containing N reference generators, the outputs of which are connected to the corresponding inputs of the switch, the output of which is the output of the sampling frequency source and connected to the ADC clock input, characterized in that it is additionally connected to the received signal amplitude calculator, the input of which is connected to ADC output, and a digital comparator, the output of which is connected to the first input of the key.

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