JPS6037836A - Receiver - Google Patents

Abstract

PURPOSE:To improve S/N by producing noise opposite in polarity to a noise generated in a receiver to mix it to a signal line. CONSTITUTION:Gates 7-9 are all turned off when a control signal A is at a high level and only noise component generated in the receiver exists during this time, then the noise component is sampled by sample and hold circuits 10, 11. While the control signal A is at a low level, the gates 7-9 are all turned on, and both the signal component and the noise component generated in the receiver are transmitted to the signal line during this time. Each output of the sample-and-hold circuits 10, 11 and right/left channel signals (including noise component) not through the smaple-and-hold circuit of a multiplex demodulator 4 are subtacted by differential amplifiers 12, 13, then the noise component is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving apparatus, and particularly to an i''M stereo data apparatus.

One method for improving the slope of an FM stereo tuner device is as shown in FIG.

In the figure, the output of the front end 1 is input to the FM detector 3 via the I P (intermediate frequency) amplifier 2.
It becomes an M stereo composite signal. This converter 1 soso signal is demodulated into left and right channel signals in an MPX (multi-Grex) stereo demodulator 4, and becomes left and right channel outputs via de-emphasis circuits 5 and 6, respectively.

A so-called high blend capacitor C1 is inserted between the outputs of both channels, and capacitors CL and C for both channels are inserted between the output lines of both channels and the ground.
R is provided. The high-blend capacitor C1 cancels out the noise components, and the high-cut capacitors CL and CR cant the high-frequency noise components contained in both channels, respectively, to improve S/N. It is.

This configuration has the disadvantage that the separation of left and right channel signals deteriorates due to the use of a high blend capacitor, and the high frequency characteristics of the signal components deteriorates due to the use of a high cut capacitor.

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional ones, and its purpose is to create noise with the opposite polarity to the noise generated inside the receiver and transfer it to the signal line. It is an object of the present invention to provide a receiving device that improves 8/N by canceling noise generated inside the receiver by mixing.

The receiving device according to the present invention includes a dirt circuit provided at at least one point in a signal line extending from an RF (high frequency) stage through 11 stages to a detection stage to control on/off of signal transmission, and a dirt circuit provided at a stage subsequent to the detection stage. A sandal hold circuit that repeatedly samples during the off period of signal transmission by the circuit and holds during the on period of signal transmission, and the output of the sandal hold circuit does not pass through the sample hold circuit after the detection stage. It is characterized in that it includes a means for mixing signals with the receiver, and is designed to reduce noise components generated inside the receiver.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a block diagram of one embodiment of the present invention, in which the reception input of the antenna RJ is connected to the front end 1 through the dart 7.
The signal is supplied to the IP signal and becomes the IP multiplied signal. This (1) signal is input to the IF amplifier f2 via the gate 8 and is amplified. The amplified IP multiplied signal is applied to the Ii"M detector 3 via the IP multiplied signal channel 9, resulting in an Ii"M stereo component signal, and the M
The signal is input to the PX demodulator 4.

The demodulated left and right channel signals are passed through sandal hold circuits IO and 11, respectively, to a differential amplifier; 7'+2.13
becomes each inverted input. These differential amplifiers 1.2, 13
A left and right channel signal is applied to each positive-phase input of the
It becomes each input of the de-emphasis circuits 5 and 6 through the filters 14 and 15/+. The respective outputs of both de-emphasis circuits 5 and 6 serve as left and right channel signal outputs.

Darts 7 to 9 are all off (closed) when the control signal is at a high level.
The sample and hold circuits 10 and 11 are configured to be turned on (open) at a low level, and sample and hold circuits 10 and 11 perform sampling at a high level of the control signal and hold operation at a low level. shall be taken as a thing.

In such a configuration, a control signal having a constant periodic pulse train as shown in FIG.
Assume that a noise component exists in the 1M detection output as shown in B). Note that, for the sake of simplicity, a state in which there is no signal component is shown.

Dirt 7-9Fit during the high level period of control signal (A)
(During this period, the noise generated in the receiver is only manually operated during the day)1. The noise components of - and 11 are filtered by the sensor hold circuits 11 and 11. During the period when the control signal (A) is at a low level, the cage door ~9
are all on, and during this time both the signal component and the noise component generated within the receiver are transmitted to the signal line, and the sample and hold circuits io and u hold the noise level just before the gate is turned on. Become.

Therefore, each output of the sample-and-hold circuit IQ, 1.1 exhibits a waveform as shown in FIG. 3(C). The outputs of the sample and hold circuits 10 and 11 and the left and right channel signals (including noise components) of the MPX demodulator 4 that have not passed through the sandal and hold circuits are sent to a differential amplifier 12.
, 1.3, the noise component is subtracted from both the waveforms of FIG. 3(B) and FIG. 3(C), resulting in the result as shown in FIG. 3(D). In other words, the level of noise components is significantly suppressed, and the improvement is significant.

The signal is turned on and off depending on the period of the control signal, but by appropriately selecting the frequency of this control signal, it is possible to prevent it from affecting the signal output.
The on/off cycle components of the control signal are removed by LPF14.15.

FIG. 4 is a block diagram of another embodiment of the present invention;
Parts equivalent to those in the figures are indicated by the same reference numerals. In this example,
A sample hold circuit 16 is provided at the output of the FM detector 3 (PM step 1/component signal output), and a differential amplifier fL7 performs subtraction processing between this hold output and the F'M stereo component signal output. Differential amplifier 17 with
The difference output is supplied to the MPX demodulator 4 via the LPF 18 and separated into left and right channel signals.

In this example as well, the signal waveforms of each part as shown in FIG. 3 are obtained, and the noise components generated within the receiver are significantly reduced as shown in (D), thereby improving the S//N. In FIG. 4, a de-emphasis circuit is provided at the output section of the MPX demodulator 4 in the same way as in FIG. 2, but it is omitted.

FIG. 5 is a block diagram of another embodiment of the present invention.
The circuit configuration of the front stage of the detector 3 is the same as that shown in FIGS. 2 and 3, and is therefore omitted. The left and right channel signals from the Ml)X demodulator 4 are input to mixers 19 and 20, respectively, and are also input to sample and hold circuits 10 and 1.1. The output of the sample hold circuit 10 of the left channel signal line is input to a mixer 20, and the output of the sample hold circuit 11 of the right channel signal line is input to a mixer 19. The respective outputs of these mixers 19 and 20 become left and right channel signal outputs via LI's 14 and 15, but the de-emphasis circuit is omitted in this example as well.

Based on the fact that the noise components included in the left and right channel signals, which are the demodulated outputs of the MPX demodulator 4, have opposite phases to each other, the sample hold circuits 10 and II mix the obtained noise components into each channel. Vessel 19.
Mixing (addition) is carried out at step 20, which is theoretically equivalent to a high blend, but has the advantage that no deterioration of separation occurs at all.

FIG. 6 shows yet another embodiment of the present invention, in which parts equivalent to those in FIG. 2-4 are designated by the same reference numerals.

In this example, the received signal level at the front end is detected by the level detector 21, and the noise (I
VC that amplifies the component (having a frequency approximately equal to the Ji' component)
This is done by controlling the gain of A (gain control amplifier) 23. The output of this VCA 23 is input to the IF amplifier 7'2 via the gate 24 and mixed with the received IF' signal. For the IF amplifier f2 and subsequent parts, each circuit configuration shown in FIG. 2.4.5 can be used. The gate 24 performs an on/off operation opposite to that of the darts 7 to 9, and therefore, the inverted signal of the control signal (A,) by the inverter 251C is used as the dart control signal.

By doing this, the gate 24 is turned on while the darts 7 to 9 inserted in the signal line are off, and the noise component is supplied according to the reception level, and only the noise component is detected by the sample hold circuit in the subsequent stage. The same effect as in the previous example can be obtained by performing a sunfring.

In each of the above embodiments, a plurality of dirt circuits 7 to 9 are provided, but it goes without saying that only the input stage cage of the front end 1 may be provided. As a control signal,
Although the output of the local oscillator may be frequency-divided and converted into a rectangular wave using a monostable multivibrator or the like, the present invention is not limited to this.

As shown above, according to the present invention, the noise components generated inside the receiver can be effectively reduced or canceled, making it possible to significantly improve the S/N ratio.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional receiver, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is an operation waveform diagram of the blocks in Fig. 2, and Figs. 4 to 6C the present invention. It is a figure which shows the block of the Example, respectively. Explanation of symbols of main parts 3...Ii'M detector 4...MPX demodulators 7 to 9, 2
4...Dirt 10, 11, 16-...Sangle hold circuit 1.
2, 13, 17-...Differential amplifier 19, 20-
・Applicant for mixer ・Representative for Guionia Co., Ltd. Patent attorney Motohiko Fujimura

Claims (1)

[Scope of Claims] (υ A dirt circuit is provided at at least one place in the signal line leading from the high frequency stage to the detection stage via the intermediate frequency stage and controls the on/off of signal transmission; a sandal hold circuit provided that performs no sampling during the off period of signal transmission by the dirt circuit and holds during the on period of signal transmission; (2) The sample and hold circuit demodulates the output of the detection stage. The left and right channel sample and hold means provided at the left and right channel signal outputs of the multi-lux stereo demodulation circuit respectively connect the outputs of the pressure and right channel sample hold means and the cloth and left channel signal outputs to each other. A receiving device characterized in that it mixes.