JPH04301917A - Am stereoscopic tuner - Google Patents

Abstract

PURPOSE:To selectively receive only an AM stereoscopic broadcasting by automatically identifying broadcasting waves concerning the AM stereoscopic tuner capable of receiving the AM stereoscopic broadcasting. CONSTITUTION:On the AM stereoscopic tuner receiving AM monoral broadcasting waves and AM stereoscopic broadcasting waves while being equipped with an AM tuner 2 and an AM stereoscopic decoder 3 to reproduce stereoscopic signals, a pilot signal converting means 8 is provided, and a signal under stereoscopic reception is generated corresponding to the pilot signal of the AM stereoscopic broadcasting waves. Then, a stereoscopic selection switch 10 is provided, and a stereoscopic reception flag is raised in the case of selecting the AM stereoscopic broadcasting wave reception. When an SD signal showing the strength of the received signal is turned to a high level during the seeking, the AM stereoscopic broadcasting waves are received by stopping the seeking when the signal during stereoscopic reception is generated, and the seeking is continued when the stereoscopic reception flag is set in the case of generating no signal in the stereoscopic reception. When the flag is not set, the seeking is stopped so as to receive both AM monoral broadcasting waves and AM stereoscopic broadcasting waves.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AM stereo tuner, and more particularly to an AM stereo tuner capable of receiving AM (amplitude modulation) radio broadcasts.

[0002] Currently, AM stereo radio broadcasting is not carried out in Japan. However, as radio broadcasts become more diverse in the future, it is expected that stereo radio broadcasts will be performed in parallel with conventional monaural radio broadcasts.

[0003] An AM stereo tuner capable of receiving such AM stereo broadcasts must be capable of automatically distinguishing between monaural broadcasts and stereo broadcasts and selectively selecting and receiving only AM stereo broadcasts. is desired.

0004

2. Description of the Related Art AM stereo radio broadcasting has not been carried out in Japan to date. Therefore, an AM stereo tuner as described above that can selectively tune and receive only AM stereo broadcast waves has not been proposed to date.

[0005]

Problems to be Solved by the Invention Conventional radio receiver systems do not have a function to distinguish between monaural broadcast waves and stereo broadcast waves. Therefore, even if the user performs a channel selection operation (seek) to receive AM stereo broadcasts,
A radio receiver receives all radio waves from receivable broadcast stations without distinguishing between monaural broadcasts and stereo broadcasts. Therefore, the user must check the content of each broadcast and confirm that it is an AM stereo broadcast before receiving it.
There is a problem in that it takes time to select a station.

[0006]

OBJECTS OF THE INVENTION The present invention aims to solve the problems of the prior art, and provides an AM stereo tuner capable of receiving AM monaural broadcast waves and AM stereo broadcast waves. The purpose is to automatically identify AM stereo broadcast waves and to selectively tune and receive only AM stereo broadcast waves.

[0007]

[Means for Solving the Problems] As shown in FIG. 1, the present invention includes an AM tuner that receives AM broadcast waves, and an AM stereo decoder that reproduces a stereo signal from the received signal. In an AM stereo tuner that can receive both AM and AM stereo broadcast waves,
A pilot signal conversion means that generates a stereo reception signal in response to a pilot signal indicating an AM stereo broadcast wave detected from an AM stereo decoder, and a stereo selection switch that sets a stereo reception flag when AM stereo broadcast wave reception is selected. During seek, when the SD signal indicating the received signal strength from the AM tuner becomes high level, or when a stereo reception signal occurs, seek is stopped and A
When an M stereo broadcast wave is received and no signal is generated during stereo reception, seek will continue if the stereo reception flag is set, and if this flag is not set, seek will be stopped and AM monaural broadcast waves and AM It is designed to receive any stereo broadcast waves.

[0008]

[Operation] The AM stereo tuner includes an AM tuner 2 to receive AM broadcast waves including AM monaural broadcast waves and AM stereo broadcast waves, and includes an AM stereo decoder 3 to separate stereo signals from the received signals. ,Reproduce. In such an AM stereo tuner, a pilot signal conversion means 8 is provided, and the AM stereo decoder 3
A stereo reception signal is generated in response to a pilot signal indicating an AM stereo broadcast wave detected from a stereo signal, and a stereo selection switch 10 is provided to set a stereo reception flag when AM stereo broadcast wave reception is selected. During seek, when the SD signal indicating the received signal strength from the AM tuner becomes high level and a stereo reception signal is generated, seek is stopped and the AM stereo broadcast wave is received, and the stereo When no signal is being received and the stereo reception flag is set, seeking is continued, and when this flag is not set, seeking is stopped and either the AM monaural broadcast wave or the AM stereo broadcast wave is received. But I will try to receive it.

Therefore, according to the present invention, in an AM stereo tuner capable of receiving AM monaural broadcast waves and AM stereo broadcast waves, the AM monaural broadcast waves and the AM stereo broadcast waves are automatically distinguished, and the AM stereo broadcast waves are automatically distinguished. It becomes possible to selectively tune in and receive only the waves.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, numeral 1 is a receiving antenna, numeral 2 is an AM tuner that receives AM radio waves, numeral 3 is an AM stereo decoder that decodes AM stereo signals, and numerals 4 and 5 are left (L) channels, respectively. and right (R) channel audio signal amplification amplifiers, respectively, and numerals 6 and 7 indicate speakers for the left (L) channel and right (R) channel, respectively.

In FIG. 1, broadcast waves including AM monaural broadcast waves and AM stereo broadcast waves inputted from an antenna 1 are selectively received by an AM tuner 2 according to a channel selection operation. When the received AM signal is a stereo broadcast wave, the AM stereo decoder 3 decodes the received AM signal and reproduces a stereo audio signal consisting of a left (L) channel signal and a right (R) channel signal. Amplifiers 4 and 5 separately amplify the L channel audio signal and the R channel audio signal from the AM stereo decoder 3 and supply them to speakers 6 and 7, respectively. As a result, the L channel sound and the R channel sound are separately emitted from the speakers 6 and 7, so that the user can listen to the sound reproduced in stereo.

FIG. 2 is a flowchart showing the operation of the embodiment shown in FIG. 1, and explains a seek operation for selecting a stereo broadcast wave.

[0013] When attempting to receive stereo broadcast waves, the stereo selection switch 10 is turned on. As a result, the ST flag in the microcomputer 9 becomes "H".

When seeking broadcast waves, the microcomputer 9
First, turn on the mute function to cut off audio from speakers 6 and 7. The microcomputer 9 increases the reception tuning frequency by 9kHz and tunes the AM tuner 2.
It is checked whether the level of the SD signal indicating the strength of the received signal from the terminal exceeds a predetermined value and becomes "H". If the level of the SD signal does not become "H", continue to increase the receiving tuning frequency by 9 kHz until the level of the SD signal becomes "H".
Repeat until. 1 where the tuning frequency is the highest frequency
When the frequency reaches 629 kHz, the tuning frequency is once lowered to the lowest frequency, 522 kHz, and the same process is repeated again.

When the AM stereo decoder 3 is decoding the AM stereo broadcast wave, the AM stereo decoder 3 outputs a pilot signal indicating the AM stereo broadcast wave. Pilot signal converter 8 generates an "H" level output when this pilot signal is output. S
When the D signal level is "H" and a "H" signal indicating AM stereo broadcast wave reception is being output, the microcomputer 9 turns off the mute function and enters the stereo broadcast reception state. When the "H" signal indicating AM stereo broadcast wave reception is not output, the S signal indicating stereo broadcast reception is output.
If the T flag is "H", the reception tuning frequency is further changed to seek AM stereo broadcast waves. On the other hand, when the ST flag indicating stereo broadcast reception is not set to "1", the mute function is turned off and a normal seek operation is performed to receive regardless of whether the AM monaural broadcast wave or the AM stereo broadcast wave is received.

[0016]

[Effects of the Invention] As explained above, according to the present invention, A
An AM stereo tuner that is capable of receiving M monaural broadcast waves and AM stereo broadcast waves automatically distinguishes between AM monaural broadcast waves and AM stereo broadcast waves, and only receives AM stereo broadcast waves. Since channels can be selectively selected and received, the number of operations required when seeking a broadcasting station in the AM stereo tuner can be reduced. Therefore, especially in the case of an automotive AM stereo tuner, it is possible to improve driving safety.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation in the embodiment of FIG. 1;

[Explanation of symbols]

2 AM tuner 3 AM stereo decoder 8 Pilot signal conversion means 10 Stereo selection switch

Claims (1)

[Claims] 1. An AM stereo tuner that is equipped with an AM tuner that receives AM broadcast waves and an AM stereo decoder that reproduces a stereo signal from the received signal, and that is capable of receiving both AM monaural broadcast waves and AM stereo broadcast waves. , the AM detected from the AM stereo decoder
a pilot signal conversion means for generating a stereo reception signal in response to a pilot signal indicating a stereo broadcast wave;
A stereo selection switch is provided that sets a stereo reception flag when stereo broadcast wave reception is selected, and when the SD signal indicating the strength of the received signal from the AM tuner becomes high level during seeking, and when the stereo reception signal is generated. stops the seek and receives the AM stereo broadcast wave, and when the stereo reception signal is not generated, continues the seek when the stereo reception flag is set, and stops the seek when the flag is not set. An AM stereo tuner is characterized in that it receives both AM monaural broadcast waves and AM stereo broadcast waves.