JPS63142727A - Mobile radio equipment - Google Patents

Abstract

PURPOSE:To reduce the deterioration in voice quality at the time of receiving fading by outputting a voice reception signal as it is when radio waves are strong and sampling and holding the voice reception signal to suppress the FM noise when the radio waves are faint. CONSTITUTION:A reception level detecting unit 6 detects a state of the strength of the radio waves. When the detected state becomes under a certain reception level, namely when the radio waves the faint and the reception level in which FM noise occurs is obtained, the reception level detecting unit 6 outputs an action indication signal 15 of sample holding to a voice process circuit 7 as 'H'. When the indication of sample holding is obtained, the voice process circuit 7 samples and holds a voice reception waveform. And if the radio waves strong and the received level is more than a certain one, the reception level detecting unit 6 detects it and outputs the through indication of the signal to the voice process circuit 7 as the indication signal 'L' of the signal 15. In this state, the voice process circuit 7 outputs the signal, as it is, from a base band filter to a voice reception signal line 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to mobile radio equipment, and particularly to improvement of audio deterioration caused by fading.

[Conventional technology]

FIG. 3 is a system diagram of a receiving section of a conventional mobile radio. In the figure, 11) an antenna, (2) a radio frequency and intermediate frequency section, 3) an FM demodulation circuit (day culminator!), 141 a baseband filter, and 5) r
! This is the audio reception signal line.

FIG. 4 is an inverse diagram of the voice reception waveform and the communication level in this conventional case. In this figure, the peaks) are the received level waveforms of the mobile radio, the zeros are the received voice waveforms, and the peaks (19 are FM noises).

Next, the operation will be explained.

When a mobile radio is mounted on a car and driven on city roads,
It is affected by the strength and weakness of radio waves, such as fading.

When this radio wave passes through the antenna 11, the radio frequency and intermediate frequency section (2), and is demodulated into a baseband audio signal by the FM demodulation circuit 31, the signal is good in areas where the radio waves are strong, as shown in Figure 4 t121. Although a received audio signal can be obtained,
In areas where the radio waves are weak, FM noise is generated by the FM demodulation circuit, as shown in Figure 4 (13), and when heard through a receiver or speaker, it sounds like a harsh, harsh sound.

[Problem that the invention seeks to solve]

Since the conventional Yusuke Musashi was configured as described above,
In areas where the radio waves were weak, there was a problem that a harsh sound was generated and the audio quality deteriorated.

This invention was made to solve the above-mentioned problems, such as the occurrence of 2M noise in areas where radio waves are weak. The purpose is to prevent this problem from occurring and to reduce deterioration in voice quality.

[Means for solving problems]

The mobile gravel clearing device according to the VC of the present invention is provided with a reception level detector that detects a reception electric field and a sample hold circuit that samples and holds the FM evening tone output, and when the detection level of the reception level detector becomes below a predetermined level, The demodulated output signal is sampled and held by a sample-and-hold circuit.

[Effect]

The mobile radio device according to the present invention aims to improve the voice quality by suppressing unpleasant 2M noise and retaining some components of the received voice signal when receiving a weak electric field such as during fading.

〔Example〕

Hereinafter, diagram Z1 will be explained as an example of the present invention.

In Figure 241, the difference from the conventional No. B18\1 is (
The received level detector (6) and the audio processing circuit (71) are added. Note that this audio processing circuit (17) includes a sample hold circuit and a signal through circuit.

Next VC1 Is this operation in Figure 1 the characteristic diagram in Figure 2? I will explain using

The reception level detector +61 detects the strength of the radio waves, and when the reception level falls below a certain level, the radio waves are weak.
When the reception level reaches a level at which 2M noise occurs, the reception level detector (6) outputs a sample-and-hold operation instruction signal; +t5 as "H" to the audio processing circuit (7). This audio processing circuit +71 samples and holds the received audio waveform as shown in FIG. 2 when there is an instruction to sample and hold. This situation is shown in Figure 42 IJ4VC.

When the radio waves are strong and the reception level is above a certain level, the reception level detector (6) detects this and starts the audio processing TCL.
路 (force to signal through instructions, 廁's instructions,) l L
Output as @. In this state, the audio processing circuit (7) directly outputs the signal from the baseband filter to the audio reception signal line (5).

Therefore, when the radio wave condition is poor, the received voice waveform is sampled and held, which has the effect of eliminating FM noise. Also, some of the signal components are sampled and held, which has the effect of reducing the deterioration of voice quality. be.

In addition, by sample-holding in the above embodiment, it is possible to prevent discontinuous points in the signal components from occurring, which can be prevented by preventing the generation of a small popping sound when heard with a receiver.

Figure 5 shows its configuration.
This is gAI with a bandpass filter (8) added. The received audio waveform in this case is shown in FIG.

[Ice 2 Day Day a) a* m) As described above, according to the present invention, when the radio waves are strong, the audio reception signal is output as is, and when the radio waves are weak or weak, the audio reception signal is output.
'g, jM is sampled and held, and the FMM sound pressure is suppressed, so does the audio quality deteriorate when it undergoes fading? There is one thing you can do to reduce it.

[Brief explanation of the drawing]

Figure 1 shows the F! System diagram of the receiving section of mobile radio equipment using AI & 1. Fig. 2 is a characteristic diagram of the voice reception waveform and reception level waveform to explain the operation of Fig. Characteristic diagram of received waveform and received level waveform, 5th
Is the figure an example of this invention? The receiving section system diagram shown in FIG. 6 is a characteristic diagram for explaining the operation of FIG. 5. 111 antenna, (21 Asahi bare frequency and intermediate frequency Ms
, 3+ F M demodulation circuit, 41 baseband filter, +51 audio reception signal line, (6) reception level detector, 7) sample hold circuit. In addition, in the drawings, the same reference numerals indicate the same or cut portions.

Claims (1)

[Claims] In a mobile radio device equipped with an FM demodulator, a reception level detector detects the level of the received signal and outputs a control signal for a period when the reception detection level is below a predetermined level, and the control signal of this reception level detector allows the above-mentioned A mobile radio device comprising a sample and hold circuit that samples and holds a demodulated output of an FM demodulator.