JPH06216720A - Automatic follow-up method for fm multiplex receiver - Google Patents

Abstract

PURPOSE:To continuously and distinctly display the same multiplex program by searching other station which is broadcasting the same multiplex program, based on a multiplex program discrimination code stored at the time when electric field intensity of a receiving station becomes a set level or below, and switching to its station, when an electric field intensity level is a set level or above. CONSTITUTION:A control part 10 receives a multiplex program consisting of FM multiplex data through an FM multiplex decoder circuit 7 and an error correcting circuit 8. A multiplex program discrimination code detecting part 10a detects a discrimination code, and stores it in a storage part 10b. When the control part 10 monitors a signal meter circuit 9 with respect to signal intensity from an intermediate frequency amplification detecting circuit 3, and an automobile separates far away from a receiving station, and it is decided that receiving electric field intensity becomes smaller than a set level, an automatic follow-up control part 10c starts to search a broadcasting station in order. When the searched station is received, its electric field intensity is compared with that of the original receiving station. When its level is higher than that of the original receiving station, a discrimination code superposed on its radio wave and a code stored in the storage part 10b are compared, and when they coincide with each other, the searched station is received and defined. Thereafter, the same processing is repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tracking method for an FM multiplex receiver, and more particularly to an automatic tracking method for an FM multiplex receiver that automatically follows a multiple program consisting of FM multiplex data superimposed on an FM broadcast signal. Regarding

[0002]

2. Description of the Related Art Conventionally, car radios as mobile receivers have been required to provide other useful data information in addition to easily obtaining data information such as traffic information. At present, in Europe, EBU
RDS (Radio Data System) has been put into practical use by (European Broadcasting Union). On the other hand, in Japan, the Telecommunications Technology Council has proposed and put into practical use an FM multiplex broadcast for effectively utilizing existing FM broadcast waves and facilities and providing additional information within a possible range.

This FM multiplex broadcasting is a system in which various digital data information is superimposed on an FM broadcasting signal and transmitted.
The contents of transmission include (1) characters, and graphics (2) receiver control signal (additional information).

The encoding system is common and simplified with the TV multiplex character broadcasting currently in practical use. That is, it is for facilitating program exchange in program production of TV multiplex character broadcasting and FM multiplex character / graphics broadcasting. The outline and the control of the character and graphic sets that are encoded and transmitted are shown below. The contents of additional information currently considered are shown below. (1) Character set Kanji, hiragana, katakana, alphanumeric characters, dynamically redefined character set, mosaic, geometric, etc. (2) Graphic Photographic graphic transmitted by pixel, mosaic graphic / dynamically redefined character set graphic transmitted by character code, geometric graphic transmitted by graphic description command code. (3) Character control Character size control, color control, flushing, concealment, etc. (4) Additional information Broadcast station name, program category, time, program identification, traffic information flag, broadcast station identification, alternative frequency list, etc. As described above, in the FM multiplex broadcasting, various messages are multiplex-transmitted to the FM broadcasting being received, and thus it becomes possible to obtain information that has not existed before.

[0005]

However, in the FM multiplex receiver utilizing such multiplex data,
When the vehicle is far away from the broadcasting station receiving the signal, or when the vehicle enters a mountainous area or the like, there is a problem that the broadcast wave becomes weak and the currently received multiple program cannot be received.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an automatic tracking method for an FM multiplex receiver capable of automatically following a broadcasting station broadcasting the same multiplex program when the broadcast wave becomes weak.

[0007]

SUMMARY OF THE INVENTION In the present invention, the above-mentioned problem is solved by transmitting an FM which is superimposed on an FM multiplex broadcast signal and transmitted.
An automatic tracking method for an FM multiplex receiver for demodulating a multiplex program consisting of multiplex data and receiving the same multiplex program based on a multiplex program identification code included in the FM multiplex data,
A multiple program identification code detecting means for detecting the multiple program identification code and a storage means for storing the code detected by the multiple program identification code detecting means are provided, and the electric field strength of the receiving station is monitored to be below a set level. When other stations broadcasting the same multiplex program are searched based on the multiplex program identification code stored in the storage means, and the electric field strength level of the station is equal to or higher than a set level, the receiving station is identified. This is achieved by switching to that station.

[0008]

The multiple program identification code detecting means detects the multiple program identification code and stores the detected multiple program identification code in the storage means. Therefore, when the electric field strength of the receiving station is monitored and falls below a set level, another station broadcasting the same multiplex program is searched for based on the multiplex program identification code stored in the storage means, and that station's When the electric field strength level is above the set level, the receiving station is switched to that station.

[0009]

1 is a block diagram of an essential part of an FM multiplex receiver that realizes an automatic tracking method according to the present invention. First, the configuration will be described. 1 is a PLL circuit, which outputs a predetermined voltage signal according to a station to be received to the FM front end 2. The FM front end 2 receives the broadcasting station input from the antenna ANT based on the voltage signal, and generates a predetermined intermediate frequency signal (IF). An intermediate frequency detection amplifier 3 amplifies and detects the intermediate frequency signal converted by the FM front end 2 to a predetermined level.

Reference numeral 4 is an MPX, which is an intermediate frequency detection amplifier 3
The detected signal input from is demodulated into a stereo signal. 5
Is an AMP (amplifier), which amplifies a stereo signal according to a volume setting value (not shown). Reference numeral 6 denotes a speaker, which is driven by the AMP 5 and outputs an audio signal.
An FM multiplex decoder circuit 7 demodulates a multiplex program consisting of FM multiplex data sent at a predetermined transmission timing. An error correction circuit 8 detects an error in the FM multiplex data demodulated by the FM multiplex decoder circuit 7 in synchronization with each group and corrects the error.

A signal meter circuit 9 detects the level of the reception state of the receiving station by monitoring the signal strength (eg, electric field strength) of the intermediate frequency signal output from the intermediate frequency detection amplifier 3.

Reference numeral 10 denotes a control unit for controlling the entire operation of the FM multiplex data receiver, which is included in the FM multiplex data and detects a multiplex program identification code for detecting the multiplex program identification code for identifying the multiplex program. It has a section 10a, a storage means 10b for storing the detected multiple program identification code, and an automatic follow-up control section 10c for automatically following the same multiplex program based on the stored code. Reference numeral 11 is a display unit for displaying the FM multiplex program by characters or figures.

FIG. 2 is a flow chart for explaining the processing of the control unit 10 of the FM multiplex receiver according to the present invention. The operation of the FM multiplex receiver of FIG. 1 will be described below with reference to this flowchart. In the state where the multiplexed program from a predetermined broadcasting station is received by the operation unit (not shown) of the FM multiplex receiver,
When the electric field strength of the broadcast radio wave of the receiving station becomes weaker than a predetermined set level, the following automatic tracking processing is performed. That is,
For example, a multiplex program consisting of FM multiplex data such as traffic information transmitted by being superimposed on the FM broadcast of the current receiving station is FM.
The control unit 10 receives the signal via the multiplex decoder circuit 7 and the error correction circuit 8 (step 101). Thereafter, the multiple program identification code detecting unit 10a detects a code for identifying the multiple programs from the FM multiple data (step 10).
2) store the code in the storage unit 10b (step 1
03).

Here, the control unit 10 monitors the signal meter circuit 9 for the signal strength from the intermediate frequency amplification detection circuit 3,
When it is determined that the vehicle is far away from the receiving station and the received electric field strength is lower than the set level (step 104),
The automatic tracking control unit 10c sequentially starts the search for broadcasting stations (step 105). When the search station is received by the search (step 106), the electric field strength of the search station is compared and checked with the original receiving station (step 107).

If the electric field strength level of the search station is higher than that of the original receiving station (step 108), the multiple program identification code included in the FM multiplex data superimposed on the broadcast wave of the search station and stored in the storage section 10b. The code of the original receiving station is compared and checked, and if they match (step 109), reception of the search station is confirmed (step 11).
0). Here, the process returns to step 104, and the same processing is repeated thereafter.

On the other hand, if the broadcasting station is not received by the search in step 106, the processing returns to the original receiving station (step 110), and after a predetermined time has elapsed, step 10
Returning to step 5, the same processing is repeated. Also, step 10
If the electric field strength level of the search station is lower than that of the original receiving station in step 8, the process returns to step 105 and the same processing is repeated.

If the multiple program identification code does not match the code stored in the storage section 10b in step 109,
Returning to step 105, the same processing is repeated thereafter.

[0018]

As described above, according to the present invention, a multiplexed program including FM multiplexed data transmitted by being superimposed on an FM multiplexed broadcast signal is demodulated, and the multiplexed program included in the FM multiplexed data is demodulated. An automatic tracking method for an FM multiplex receiver for receiving the same multiplex program based on an identification code, the multiplex program identification code detecting means detecting the multiplex program identification code, and the multiplex program identification code detecting means. A storage unit for storing the code is provided, and the same multiplex program is broadcast based on the multiplex program identification code stored in the storage unit when the electric field strength of the receiving station is monitored and falls below a set level. When another station is searched and the field strength level of that station is above the set level, the receiving station is switched to that station, so that the same multiplex program can be continuously and clearly displayed. The effect is obtained that that.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an FM multiplex receiver that realizes an automatic tracking method according to the present invention.

FIG. 2 is a flowchart for explaining the processing of the control unit 10 of the FM multiplex receiver according to the present invention.

[Explanation of symbols]

 1 PLL circuit 2 FM front end 3 Intermediate frequency detection amplifier 7 FM multiplex decoder circuit 8 Error correction circuit 9 Signal meter circuit 10 Control unit 11 Display unit

Claims (1)

[Claims] 1. A demodulated multi-program consisting of FM multiplexed data sent superimposed on an FM multiplexed broadcast signal,
An automatic tracking method of an FM multiplex receiver for receiving the same multiplex program based on a multiplex program identification code included in multiplex data, the multiplex program identification code detecting means for detecting the multiplex program identification code, and the multiplex program identification. A storage unit for storing the code detected by the code detection unit, and the same based on the multiple program identification code stored in the storage unit when the electric field strength of the receiving station is monitored and the level becomes lower than a set level. When you search for another station that is broadcasting a multiplex program and the field strength level of that station is above the set level,
An automatic tracking method for an FM multiplex receiver, characterized in that the receiving station is switched to that station.