JP3618438B2 - Spread spectrum receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improved technique of a spread spectrum receiver that can detect and remove jamming radio waves in a reception band.
[0002]
[Prior art]
In general, a spread spectrum communication type receiver has an exclusion function for eliminating interference with respect to interference waves other than the desired wave. When the desired wave and interference wave are received, this exclusion function restores the desired wave to the pre-spread bandwidth by correlation with the reference signal, spreads the interference wave beyond the input band, and emphasizes only the desired wave Thus, the influence of other interference waves is suppressed, and the interference waves are separated through a band-pass filter.
[0003]
However, when the interference wave level exceeds the processing gain of the receiver, normal reception capability cannot be maintained.
Therefore, for example, Japanese Patent Laid-Open No. 4-91528 discloses channel separation means for separating a spectrum spread received signal into at least three band channels having different center frequencies, and comparison means for comparing the magnitudes of signal components of the respective channels. Output level adjusting means provided for each channel, control means for controlling each adjusting means according to the comparison result of the comparing means, and attenuating a channel output having a large output level, and the control means. There is disclosed a spread spectrum receiver including combining means for combining the output of each channel.
[0004]
In this receiver, an interference wave that becomes a disturbance is detected by comparing adjacent filter outputs, the output of the detected filter is attenuated to an appropriate level by the attenuation control means, and then the output of each filter is synthesized. Depending on the number of channel separation means, that is, the number of filters, the ability to remove interference waves increases.
However, the receiver having such a configuration has technical problems described below.
[0005]
[Problems to be solved by the invention]
In other words, in the receiver having the configuration disclosed in the above-mentioned publication, if an in-band signal is not attenuated and an attempt is made to detect an interference wave by subdividing the band, the number of filters becomes too large. Considering the miniaturization of the receiver and the simplification of the circuit, it becomes a heavy burden, and a small and inexpensive configuration cannot be obtained.
[0006]
The present invention has been devised in order to solve the above problems, and the object of the present invention is to detect the level and frequency of the interference wave, and to detect the level of the detected frequency in the received band. It is an object of the present invention to provide a spectrum spread receiving apparatus that is downsized and has a reduced receiver size and circuit.
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention comprises a sweep local signal generating means for outputting a sweep signal is swept in frequency of the same bandwidth as one of the signals distributed from the input scan Bae Kutoramu received signal, the A mixer circuit that mixes one of the signals distributed from the spectrum reception signal and the sweep signal, and a narrowband bandpass filter that selectively passes only the interference wave component out of the output signal of the mixer circuit ; Detection means for detecting the level and frequency of the interference wave component that has passed through the narrow-band bandpass filter, and receiving the signal from the detection means, the level of the interference wave component included in the other received signal to be distributed is lowered. and a level adjusting means for adjusting the sweep local signal generating means, in particular is controlled by sweeping a control signal by the output of said detection means And to allow removal of the interference wave.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a main part of a spectrum spread receiver according to the present invention.
In the figure, 1 is a mixer circuit, 2 is a band pass filter (BPF), and 3 is an IF amplifier. The spectrum spread signal, which is an information signal, is correlated with a fixed local signal (reference signal) input to the mixer circuit 1 through the PLL circuit 4 by being input to the mixer circuit 1 as in the prior art. After passing through the band-pass filter 2 with its bandwidth reduced, it is amplified by the IF amplifier 3 and taken out as an output signal.
[0009]
In addition, in the present invention, the signal that has passed through the band-pass filter 2 is divided into two systems, the signal that is directly input to the IF amplifier 3 and the signal that is input to the circuit unit for detecting and removing the interference wave. By superimposing the control input from the removal circuit section on the signal before the IF amplifier 3, the interference wave is removed.
The removal circuit unit includes a second mixer circuit 5 to which one of the distributed signals is input, a narrowband bandpass filter 6 connected to the output side of the second mixer circuit 5, and a bandpass filter. 6, a detection / integration circuit 7 connected to the output side, a level detection controller 8 that receives an output signal of the detection / integration circuit 7, a sweep local signal generator 9 and a level adjustment circuit controlled by the level detection controller 8. 10.
[0010]
The sweep local signal generator 9 is operated by the oscillation signal from the reference oscillator 11 shared with the PLL circuit 4 and is controlled by the sweep control signal from the level detection controller 8, and the second mixer circuit 5. Sweeps the frequency of the local signal applied to the.
FIG. 2 shows processing waveforms in each part of FIG. The signal waveform shown in (1) in the figure is the output signal a sent from the mixer circuit 1, and the sweep local signal generator 9 responds to this output signal a as shown in (2). A sweep signal b having the same bandwidth as the output signal a is output, and these signals a and b are mixed by the second mixer circuit 5.
[0011]
As a result, the second mixer circuit 5 outputs a signal c obtained by subdividing the output signal a with the sweep signal b, as shown in FIG.
Here, when a narrow-band interference wave d, which is a disturbing wave component, is mixed with the output signal a (in fact, in (1), the difference component of the interference wave with respect to the information signal is detected. As shown in (4), the component that passes through the narrow band-pass filter 6 is only the interference component d that is an excessive component, and the frequency component and magnitude of the interference component d are detected / integrated. It is detected by the circuit 7.
[0012]
The level detection controller 8 receives the output signal from the detection / integration circuit 7 and sends a signal corresponding to the frequency and magnitude of the interference wave component d to the level adjustment circuit 10. The level adjustment circuit 10 receives this signal and sends a signal corresponding to the output signal a. As a result, only the information signal e is output from the IF amplifier 3 as shown in FIG.
[0013]
FIG. 3 shows details of the level adjustment circuit 10. The level adjusting circuit 10 shown in FIG. 1 includes a resonant circuit including a coil L1 and a variable capacitance diode (varicap) D connected in series to the coil 1, and a variable circuit connected to the resonant circuit. It includes an attenuator R, L2 and a capacitor C connected to a connection node between the variable capacitance diode D and the variable attenuator R.
[0014]
In the level adjustment circuit 10, a connection terminal for the band-pass filter 2 and the IF amplifier 3 is provided on one end side of the coil L1. Further, by applying a control voltage from the level detection controller 8 to the variable capacitance diode D via L2, the resonance frequency of the interference wave component d is changed, and an attenuation level control voltage is applied to the variable attenuator R side. Thus, the attenuation is adjusted.
[0015]
In the above embodiment, the output side of the level adjustment circuit 10 is connected between the band-pass filter 2 and the IF amplifier 3. However, as shown by a dotted line in FIG. Is possible.
[0016]
【The invention's effect】
As described in detail in the above embodiments, the spread spectrum receiver according to the present invention senses interference waves in the reception band in detail without using a large number of filters as compared with the prior art. Therefore, there is an advantage that the circuit can be simplified and the device can be reduced in size and can be provided at a low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main part of a spectrum spread receiver according to the present invention.
FIG. 2 is a schematic explanatory diagram showing processing waveforms in each part of FIG. 1;
FIG. 3 is a specific circuit diagram of a level adjustment circuit.
[Explanation of symbols]
5 Second mixer circuit 6 Narrow band-pass filter 8 Level detection controller 9 Sweep local signal generator 10 Level adjustment circuit

Claims (1)

A swept local signal generating means for outputting a swept signal swept at a frequency having the same bandwidth as one of the signals distributed from the inputted spectrum received signal;
A mixer circuit for mixing one signal distributed from the spectrum received signal and the sweep signal ;
Of the output signal of the mixer circuit, a narrowband bandpass filter that selectively passes only the interference wave component,
Detection means for detecting the level and frequency of the crosstalk component that has passed through the narrowband bandpass filter;
Level adjustment means for receiving a signal from the detection means and adjusting the level of the interference wave component included in the other received signal to be distributed downward ;
The spectrum spread receiver, wherein the sweep local signal generating means is controlled by a sweep control signal based on an output of the detecting means .

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