RU2459353C1 - Method of receiving radio signal - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: method of receiving a radio signal involves filtration with noise suppression of the received radio signal, wherein the radio signal is converted to a signal of the frequency band of modulating signals; the entire scanning band is selected using an input filter at the output of an antenna; the scanning band is compressed via multistep frequency conversion using a frequency synthesiser, while breaking the scanning band at each conversion step by ordering the main and image reception channels, wherein the frequency spacing of the frequency synthesiser is selected equal to 2Δω_ϕi and the width of each reception window for the main and image channels is equal to Δω_ϕi, where i is the number of conversion,

so as to facilitate folding of each reception channel into one transmission band Δω_ϕi.

EFFECT: enabling instantaneous signal scanning in a wide frequency band without a priori information on the signal bandwidth.

2 dwg

Description

The invention relates to radio engineering and can be used in the development of monitoring systems for radiation sources in a wide frequency range.

Known methods for receiving radio signals using radio receivers containing several local oscillators. In [1, 2], a method of using a frequency synthesizer (MF) as a local oscillator is considered.

The disadvantage of this method is the lack of use of mirror channels as additional reception channels.

Closest to the proposed method of receiving a radio signal is a method of suppressing noise of a received radio signal, which is converted into a radio signal of a frequency band of modulating signals, which consists in generating a radio signal and filtering the radio signal of a band of modulating radio signals using the first bandwidth if the radio signal level is higher than the first threshold value, and using a second bandwidth smaller than the first bandwidth if the radio signal level is below the second threshold value [3].

The disadvantage of the prototype method is that implemented in this method, the filtering of the signal bandwidth of the modulating signals using the first bandwidth if the signal level is higher than the first threshold value, and using a second bandwidth less than the first bandwidth if the signal level is lower the second threshold value, although it provides the detection of radio emission sources, however, if it is necessary to expand the range of the span, it will require fundamental alterations of the detector circuit, which It clears the frequency range of its application.

The objective of the invention is the provision of instant review of signals in a wide frequency band in the absence of a priori information about the width of the spectrum of the signals.

с тем, чтобы обеспечить сворачивание каждого канала приема в одну полосу пропускания Δω_фi...The problem is achieved in that in a method for receiving a radio signal, including filtering with noise suppression of the received radio signal, in which the radio signal is converted into a signal of a frequency band of modulating signals, according to the invention, the entire field of view is isolated using an input filter at the output of the antenna, and the field of view is compressed by multi-stage frequency conversion using a frequency synthesizer, dividing the field of view at each conversion step by alternating the main and mirror receiving channels, while the frequency grid step the frequency synthesizer is chosen equal to _{2Δω fi} , and the width of each receive window for the main and mirror channels is equal to Δω _fi , where i is the conversion number,

in order to ensure the folding of each reception channel into a single passband Δω _{phi ...}

Achievable technical result of the invention is a quick overview of a given frequency band using the midrange (multi-frequency local oscillator) for both the main and mirror receiving channels.

, N - число преобразований. Для i-го преобразования сжатие с учетом зеркальных каналов приема µ_i=2n_i, где n_i - число частот СЧ на данном преобразовании.Figure 1 presents a diagram of a radio receiving device that ensures the operation of the proposed method. Consider the proposed method (figure 1). The received signal to the antenna 1 through a broadband input filter 2, the passband of which covers the entire field of view, is fed to the first frequency converter 4, to the second input of which a signal is supplied from the first frequency synthesizer 3 (first multi-frequency local oscillator), the output of the first converter 4 is connected to the input the first filter of intermediate frequency 5, the passband of which is µ ₁ times smaller than the entire span, from the output of filter 5, the signal goes to the first input of the second frequency converter 7, to the second input of which A second frequency synthesizer 6 is connected, from the output of the second frequency converter 7, the signal is fed to a filter 8, the band of which is already the span in µ ₁ gµ ₂ , where µ ₁ is the compression during the first frequency conversion, and µ ₂ is the compression of the span during the second conversion frequency, after which the signal enters the threshold device 9, where a decision is made about the detection or absence of a signal. In the general case, an increase in the number of frequency converters and, accordingly, frequency synthesizers makes it possible to increase the compression of the span in M times, where

, N is the number of transformations. For the ith transform, compression taking into account the mirror channels of reception is µ _i = 2n _i , where n _i is the number of frequencies of the midrange on this transform.

The number of frequencies for each midrange is determined by the characteristics of the filters after the corresponding conversion. In this case, with each subsequent frequency conversion, the step of the midrange frequency grid decreases and in the final case it is determined by the narrow-band output filters.

Consider some relationships for the selection of midrange frequencies.

Denote by Δω _{obz the span} , and Δω _f the passband of the filter. In order to cover the entire reconnaissable field of view, it is required to use midrange with the number of frequencies

where n >> 1. In expression (1), the factor 1/2 takes into account the use of an additional mirror receive channel. An important advantage of this approach is the use, along with the main channels, of mirror channels in the field of view, which simplifies the requirements for the circuit and for the frequency synthesizer. In this case, the number of required components of the midrange signal is halved. An illustration of the conversion of signals in the frequency band is shown in Fig.2. The portions of the span of view passing through the main and mirror channels are designated “O” and “3”, respectively. The indices determine the number of the component of the local oscillator signal, which ensures the passage of signals in a given region of the field of view. For simplicity of reasoning, we will assume a filter after frequency conversion with a rectangular frequency response.

According to figure 2, the main and mirror channels in the field of view occupy the following frequency ranges:

,

,

where the first sum corresponds to the frequency windows occupied by the main channels, and the second sum corresponds to the windows occupied by the mirror channels, the width of each window Δω _ф , 1 (ω) is a single jump. Thus, the combination of the main and mirror channels provides an overview of the entire frequency band.

Consider some of the relationships for the circuit in figure 1. Let the signal of the main channel with number λ at the detector input have the form

- амплитуда сигнала,

,

- частота,

- начальная фаза сигнала.Where

- the amplitude of the signal,

,

- frequency

- the initial phase of the signal.

Frequency synthesizer signals

Ф _Гλ (t) = (ω _Г1 + (λ-1) · 2Δω _Ф ) t + ψ _Гλ ,

,

Шаг сетки частот, равный 2Δω_ф, обеспечивает перекрытие всей полосы обзора за счет использования как основных, так и зеркальных каналов приема.wherein 2Δω _F - Step mesh midrange frequencies equal to the sum of the bandwidths of specular and main channels, u _mGλ - amplitude, ω _Gλ = ω _r1 + (λ-1) · 2Δω _O) - frequency, ψ _Gλ - the initial phase of the local oscillator signal with the number λ, while for the main channel with number λ, for definiteness, the condition

,

The frequency grid pitch equal to 2Δω _f provides for the overlap of the entire viewing band due to the use of both the main and mirror receiving channels.

We consider the frequency converter as an inertialess multiplier. At the output of the frequency converter we have

Suppose that the filter after conversion for the λ-th component of the local oscillator selects the difference intermediate frequency, then (4) can be rewritten in the form:

Now consider the signal of the reception mirror channel with number λ at the detector input

.

.

, при этом

, т.е. частота приема зеркального канала отличается от основной частоты приема на удвоенное значение промежуточной частоты.For a mirror channel with number λ, the condition

, wherein

, i.e. the frequency of reception of the mirror channel differs from the main frequency of reception by twice the value of the intermediate frequency.

At the output of the frequency converter for the mirror channel, we have

As in the previous case, the filter after conversion for the λ-th component of the local oscillator selects the difference intermediate frequency for the mirror channel, i.e.

Before each conversion using the midrange, we have an alternation of the main and mirror channels.

Information sources

1. Vakin S.A., Shustov L.N. Fundamentals of radio countermeasures and electronic intelligence. M .: Sov. Radio, 1968, 444 p.

2. Pilyagin V.V. Theory of n-dimensional frequency conversion with perfect non-linear resistance. - Radio engineering, 1966, v.21, 38, p. 37-42.

3. Application No. 2004115738, Н04В 1/00, publ. 03/27/2005.

Claims (1)

A method of receiving a radio signal, including filtering with noise suppression of the received radio signal, in which the radio signal is converted into a signal of a frequency band of modulating signals, characterized in that the entire field of view is isolated using an input filter at the output of the antenna, the field of view is compressed by multi-stage frequency conversion using a frequency synthesizer, dividing the field of view at each step of the conversion by alternating the main and mirror receiving channels, while the frequency grid pitch of the frequency synthesizer is chosen equal to _{2Δω φi} , and the width of each receive window for the main and mirror channels is equal to Δω _fi , where i is the transformation number,

, in order to ensure the folding of each receiving channel into one passband Δω _fi .

Images