JPS6024734A - radio receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a radio receiver that is capable of removing interfering radio waves near reception frequencies.

Conventional configuration and its problems In general, a radio receiver amplifies the received signal from an antenna 1 with a high frequency amplifier 3 as shown in FIG. , a frequency mixer 4 to which a local oscillation signal from a PLL-configured local oscillator 5 including a PLL controller 8 is applied, converts it into an intermediate frequency signal, and converts the intermediate frequency signal from the frequency mixer 4 into an intermediate frequency signal, and includes a ceramic filter 15. It was configured to amplify it with an intermediate frequency amplifier 18 and apply it to an FM detector 19 to convert it into an audio signal, and then add the audio signal from the FM detector 19 to a stereo demodulator 21 to extract left and right signals. . In order to eliminate the influence of interference waves near the receiving frequency, a high frequency tuning circuit 2.
Ceramic filter 16.17 and anti-birdie
A jamming wave removal circuit consisting of a filter 20 and the like was connected to prepare for performance deterioration due to jamming waves.

However, in the above-mentioned radio receiver, the jamming wave removal circuit is not necessary in the reception state where there is no jamming wave,
The disadvantage was that the provision of these elements actually worsened characteristics such as distortion and separation.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide a radio receiver that can effectively eliminate interference waves without deteriorating characteristics such as distortion and separation. purpose.

Structure of the Invention In order to achieve the above object, the present invention receives interference radio waves near the desired reception frequency received by a receiving circuit that receives desired broadcast radio waves and demodulates the audio signal included in the carrier wave, and detects the level thereof. A level detector and a monitoring means that continuously monitors the frequency near the desired receiving frequency during the receiving period of the receiving circuit and generates a plow control signal based on the signal from the detector when the detector detects an interfering radio wave. The apparatus is characterized in that the interference radio wave removal circuit is selectively connected to the reception circuit according to the control signal from the monitoring means.

DESCRIPTION OF THE EMBODIMENT FIG. 2 shows an embodiment of the radio receiver of the present invention. In FIG. 2, the difference from that in FIG. and amplify the high frequency signal from the high frequency intensifier/suppressor 9 to a grease scaler 12. A PLI including a loop filter 13 and a PLL controller 8.

The local oscillation signal from the local oscillator 11 of the configuration is added to the frequency mixer 1o, which converts it into an intermediate frequency signal, and the intermediate frequency signal from the frequency mixer 10 is amplified by an intermediate frequency amplifier 23 including a ceramic filter 22. The interference radio waves included in the received signal are detected by adding the level detector 24 to the level detector 24. still,
High frequency tuning circuit constituting the interference signal removal circuit 2. The ceramic filters 16, 17 and the anti-birdie filter 2Q are configured to be switched and connected to a receiving circuit that receives desired broadcast radio waves and demodulates audio signals using switches 26a to 26d.

Furthermore, using the microcomputer 27 that constitutes the PLL controller 8, the frequency near the desired reception frequency is continuously monitored during the reception period, and when the level detector 24 detects an interfering radio wave, the signal from the detector 24 is used. By generating a control signal and operating the switches 20a to 26d using the control signal, the above-mentioned jamming wave removal circuit is connected to the receiving circuit.

Here, a program for detecting interference radio waves in the microcomputer 27 is shown in FIG. This detection program sets the desired frequency as the middle, sets fU as the upper limit, and fL as the lower limit, and constantly monitors fL to fU t at intervals of Δf. It is designed to output a detection signal.

In such a radio receiver, in a state where there is no interfering radio waves, various broadcast radio waves transmitted from the FM antenna 1 are sent to the high frequency amplifier circuit 3 by CO from the loop filter.
By tuning with voltage, only the desired received radio waves are amplified and enter the frequency mixer. and a local oscillator 5. Prescaler 6, PLL controller 8. The loop fi/v is mixed with the oscillation voltage from Tough's PLL loop and converted to an intermediate frequency of 10.7MI+l. From there, the signal that passes through the intermediate frequency filter 15 and whose band is limited is amplified by the intermediate frequency amplifier 18, detected by the FM detector 19, and further separated into a right channel signal and a left channel signal by the stereo demodulator 21. Output.

On the other hand, in the reception state described above, the microcomputer 2
A high frequency amplifier 91 and a frequency mixer 10 separately provided under the control of 7. Local oscillator 11° prescaler 12. A front end section consisting of a loop filter 13, a ceramic filter 22I, an intermediate frequency amplifier 23. Level detector 24
Interfering radio waves are monitored by If interference radio waves are detected as a result of this monitoring, the level detector 24
A level signal is sent to the microcomputer 27. The levels are compared inside the microcomputer 27, and if it is determined that the signal is above a certain level, the microcomputer 27 immediately switches on each switch 26a to 26.
A switching signal is output to d, and each switch 26
A to 26d are switched to a state in which the received signal passes through a jamming wave removal circuit to prepare for interference.

Effects of the Invention As described above, according to the present invention, the jamming wave removal circuit is configured to be switched and connected to the receiving circuit depending on the presence or absence of jamming waves, so that characteristics such as distortion and separation are not deteriorated. It has the advantage of being able to remove jamming waves, and in achieving the performance of the receiver, it is possible to balance the contradictory issues of ensuring the ability to remove jamming waves and ensuring reception characteristics and audio characteristics.

In particular, in order to satisfy West Germany's FTZ standard, it is currently necessary to make some compromises in basic performance, but if the present invention is used, input terminal immunity, which is one of the FTZ standards, can also be achieved. It has the advantage that basic performance can be ensured even in a state where there is no interference.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional radio receiver, FIG. 2 is a block diagram showing an embodiment of the radio receiver of the present invention, and FIG.
The figure is a flowchart of the detection program of the receiver. 2-...High frequency tuning circuit, 3,9...High frequency increase 1
Equipment, 4, 1o... Frequency mixer, 5, 11 ・
・Local oscillator, 6, 12...Prescaler, 7, 1
3...Loop filter, 8-...PLL controller, 15.16, 17.22...Ceramic filter, 18.23--Intermediate frequency amplifier, 19...F
M detector, 24...Level detector, 20--Filter, 21...Stereo demodulator, 26a-2
6d...Switch, 27-...Microcomputer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A receiving circuit that receives the desired broadcast radio wave and demodulates the audio signal included in the carrier wave, a level detector that receives interfering radio waves near the desired reception frequency received by this receiving circuit and detects their level, and removes the above-mentioned interfering radio waves. The interfering radio wave removal circuit continues to monitor the frequency near the desired reception frequency during the reception period of the above receiving circuit, and when the above detector detects an interfering radio wave, the signal from the above detector also generates a plow control signal. What is claimed is: 1. A radio receiver comprising: a monitoring means for monitoring, and configured to switch and connect the interference wave removal circuit to the receiving circuit in response to a control signal from the monitoring means.