JPS59194536A - Product detecting type noise blanker - Google Patents

Abstract

PURPOSE:To improve the operation of a noise blanker by connecting a noise removing gate to an intermediate frequency amplifying stage of a receiving part of a radio equipment and switching the cutoff frequency of an HPF passing a signal controlling the noise removing gate. CONSTITUTION:The noise removing gate 3 is connected to the intermediate frequency amplifying stage of the receiver and a signal branched from the prestage part 1 is detected by a product detector 52 through a buffer 51. The output of the detector 52 is applied to an one-shot multivibrator 55 through any one of the HPFs 54A-54C to generate a gate control pulse 56 and open/close the gate 3, so that the signal is separated from a noise pulse and the output of the gate 3 is outputted through any one of BPFs 4A-4C. The cutoff frequency the HPFs 54A-54C is changed in accordance with the reception of FM, AM and SSB and switches 6A-6D switching the HPFs 54A-54C and the BPFs 4A-4C are interlocked each other to switch the filters. Consequently, the removing function of noise pulses less than the amplitude of the signal is improved and the troublesome operation can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is based on a patent application previously filed by the applicant in 1982.
No. 223595 of 2013 relates to improvements in "Product detection type noise blanker".

First, to briefly explain Japanese Patent Application No. 57-223595, as shown in FIG. 1, in the intermediate frequency signal circuit A - + B of the receiver, 1 and 2 are front-stage parts with relatively wide band characteristics; 3 is a noise removal dirt, and 4 is a filter following this. The output B is supplied to a demodulator via an amplification stage. A control output detection circuit 5 for opening and closing the gate 3 is branched from the previous stage, passes through a buffer amplifier 51, and is added to 52 with the same injection frequency 53 to perform product detection.
The output is passed through a high noise filter 54 to separate the p signal and the noise pulse, and a one shot multi 55 generates a dirt control signal 56.

In this way, the signal and noise are detected separately in the demodulated frequency band, so noise/? It has the characteristic of being able to detect ruses.

Furthermore, if the wandering output of 52 is observed in detail, it can be seen that the occupied band of the demodulated signal differs depending on the signal mode. In other words, as shown in Figure 3 (A), in FM, the demodulated signal has a maximum of 20
It is distributed up to about kHz, with AM at a maximum of about 10 kHz as shown in (B), and SSB at a maximum of about 3 kHz (as in
Usually, it is a single tone of 1 kHz or less, as shown in (D). Therefore, the cutoff frequency of the Hinogus filter 54 combined with this is (A) 20kHz, (B) 10
Naturally, it is desirable to set it to an optimal value such as kHz, (C) 4 kHz, and (D) 2 kHz. Furthermore, this cutoff frequency can be adjusted automatically by changing the applied bandpass filter or the band. (・It is convenient to set it υ-wise on the actual JJI.

The present invention has been made to embody the above idea, and as shown in FIG. The product is detected by 52 through buffer amplifier 51, and the output is sent to high-noise filters 54A to 54.
'+' for any of C? +r and one shot multi 55
In addition, the dirt control) e system 56 is generated, but the switches 6A and 6B that change over the filters 54A to 54C are the switches 6C and 6D that change over the bandpass filters 4A to 4C.
The device is characterized in that it can be switched in conjunction with the mode switch, or in conjunction with the mode switch, or in conjunction with both the band switch and the mode switch.

As described above, the present invention improves the operation by switching the cutoff frequency of the high speed filter of the "product detection type noise blanker" of the previous application, and also links the switching with the band switch and mode switch. This has the effect of eliminating the complexity of operation.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a noise blanker of the duct detection type, FIG. 2' is an example of a block circuit diagram of the present invention, and FIG. 3 is an explanatory diagram of the duct detection output and the noise blanker. 1.2... Front section, 3... Noise removal dirt, 4.
4A, 4B, 4C... Bandpass filter, 51... Buffer amplifier, 52... Product detector, 54, 54
A・54B・54C・・・Bypass filter, 55・-
・One shot multi. Patent applicant: Yaesu Musen Co., Ltd.\--LJ” 1-1.2+

Claims (1)

[Claims] A noise removal dart is provided in the intermediate frequency amplification stage of the reception section of the radio receiver or radio transceiver, and a control output detection circuit for extracting the gate control output from the stage before the dirt is connected to the carrier of the signal. The product detection injects the same frequency and the following pass filter, and the cutoff frequency of the high pass filter is set by a changeover switch for the plurality of filters following the dirt. Alternatively, a product detection 1-set noise blanker characterized in that it is switched in conjunction with a mode changeover switch or both a filter changeover switch and a mode changeover switch.