JPH04137812A - Automatic channel selection controller for rds receiver - Google Patents

Abstract

PURPOSE:To prevent changeover to a station in which multi-path disturbance takes place and to keep an excellent reception state by providing a multi-path disturbance section to the controller. CONSTITUTION:A level detection section 7 detects a reception signal level based on a level of an intermediate frequency signal in an FM detection section 3 and a multi-path disturbance detection section 12 detects the presence of multi- path disturbance. A controller 10 applies setting control of a frequency division ratio of a phase locked loop circuit 6 so that the reception is not selected to a station having a multi-path disturbance when a reception signal level of a frequency information code station exceeds an original reception station level, no multi-path disturbance is detected in the frequency information code station. Thus, the changeover to the reception of a station in which multi-path disturbance takes place regardless of an excellent reception electric field is prevented and an excellent reception state is kept.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to RDS (
R for automatic tuning of reception of radio data system)
This invention relates to an automatic channel selection control device for a DS receiver.

[Conventional technology]

When a broadcast station broadcasts, information related to the program content is multiplex modulated and transmitted as data, and the transmitter side can select the desired program content based on the modulated data, allowing the radio listener to select the desired program content. There is an RDS that can provide this service.

This RDS data includes a network identification code (hereinafter referred to as PI), a traffic information bureau selection code (hereinafter referred to as TP).
), traffic announcement recognition code (hereinafter referred to as TA), program service name information code (hereinafter referred to as PS) such as broadcasting station name or network name, frequency information code of network stations broadcasting the same program (hereinafter referred to as (referred to as AF), etc.

By the way, in the case of a vehicle-mounted receiver, as the vehicle travels, the reception condition of the broadcast wave being received may deteriorate.

However, in the case of RDS broadcasting, as mentioned above, it is possible to obtain the AF data of a group of network stations broadcasting the same program, so by storing this AF data in memory, the received signal level ( It is possible to select another station on the same network that has a larger IT field strength).

[Problem to be solved by the invention]

However, if the receiving state is judged only by the received electric field level, there is a problem in that the station may switch to a station where multipath interference is occurring.

Note that Japanese Patent Laid-Open No. 2-105731 has an approximation technique.

This invention was made in order to solve the above-mentioned problems. Even if the received electric field level is good, it is possible to prevent the reception from switching to a station where multipath interference is occurring, and to maintain a good prevention state. An object of the present invention is to obtain an automatic channel selection control device for an RDS receiver that can maintain the RDS receiver.

[Means to solve the problem]

The automatic channel selection control device for an RDS receiver according to the present invention comprises:
A phase-locked loop circuit for setting the front-end tuning of the DS receiver, a multipath interference detection section for detecting the presence or absence of multipath interference from the FM detection output of the FM detection section, and a frequency information code for at least one station. If the above frequency information code memory is stored in the built-in frequency information code memory, and the received signal level of the frequency information code station does not exceed the original receiving station level, or exceeds the original receiving station level and the original receiving station has at least Frequency division of the phase-locked loop circuit is performed so that when there is no path interference detection and at least multipath interference of the frequency information code station is detected by the multipath interference detector, the reception is not switched to the station receiving multipath interference. A controller that performs ratio setting control is provided.

[For production]

The controller in this invention is configured to control the frequency information code station when the received signal level does not exceed the original receiving station level, or when the received signal level of this frequency information code station exceeds the original receiving station level and the original receiving station When at least no multipath interference is detected by the multipath interference detection unit at the station, and at least multipath interference is detected by the multipath interference detection unit at the frequency information code station, the station experiencing multipath interference receives The frequency division ratio of the phase-locked loop circuit is controlled to prevent switching.

〔Example〕

Embodiments of an automatic channel selection control device for an RDS receiver according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment.

In FIG. 1, reference numeral 1 denotes an antenna, and FM multiplex broadcast waves received by the antenna 1 are received by a desired receiving station at a front end 2. The reception signal received by this front end 2 is an intermediate frequency signal (
After being converted into IF), it is supplied to the FM detection section 3.

Further, the front end 2 is configured to perform channel selection control by a phase lock loop circuit 6 including a programmable frequency divider. The frequency division ratio of this PLL circuit 6 is set by a controller 10L, which will be described later.

By setting the frequency division ratio by the controller 10, the front end 2 performs the channel selection operation as described above.

Further, the detection output of the FM detection section 3 is supplied to a multiplexer (hereinafter referred to as MPX) modulation circuit 5 via an NK (noise canceller) 4.

In this case, in the case of stereo broadcasting, left (L) channel and right (R,) channel audio signals are output.

Further, the detection output of the FM detection unit 3 is inputted to the RDS decoder 9 via a 57 KHz band pass filter 8, and the output of this RDS decoder 9 is converted into distinguishable data by the controller 10. It has become so.

The controller 10 has a built-in AF memory 11, which stores information on receiving stations taken in by the controller IO,
That is, various information such as the above-mentioned PI, AFPS, TP, TA, etc. are stored as AF data in the AF memory 11.

Further, a level detection section 7 is provided that detects the received signal level (IT field strength) based on the IF signal level in the FM detection section 3, and the received signal level detected by the level detection section 7 is supplied to the controller 10. It is now possible to do so.

Further, from the output end of the NK4, a multipath interference detection section 12 detects the presence or absence of multipath interference, and the detection result of this multipath interference detection section 12 is supplied to the controller 10. ing.

In the embodiment shown in FIG. 1, the multipath interference detector 12 detects multipath interference by using the output signal of the bypass filter (not shown) of the NK4. An output signal of a signal strength indicating circuit (not shown) may be used.

Next, the operation will be explained. F received by antenna 1
A desired station of the M multiplex broadcast waves is selected by the front end 2, converted to an intermediate frequency, and then supplied to the FM detection section 3.

The detection output of the FM detection unit 3 is supplied to the MPX demodulation circuit 5 via the NK 4, where it is demodulated, and in the case of stereo broadcasting, it is separated into L and R channel stereo audio signals and output.

Further, the output of the FM detection section 3 is inputted to an RDS decoder 9 via a bandpass filter 8, and the output of this RDS decoder 9 is converted into data that can be discriminated by a controller 10.

The controller 10 receives the above information PIAF, PS,
TP, TA, etc. are taken in and the AF data is stored in the AF memory 11.

Furthermore, the received signal level (field strength) is detected by the level detector 7 based on the level of the intermediate frequency signal in the FM detector 3, and the detection result is output to the controller 10.

Further, a multipath interference detection section 12 detects the presence or absence of multipath interference from the output section of the NK4, and the result of the detection is output to the controller 1o.

Here, the operation of the controller 10 that controls not to switch to an AF station when multipath interference is detected, which is a feature of the present invention, will be explained along the flowchart of FIG. 2.

It is assumed that the AF memory 11 has already stored AP data for one or more stations.

First, in step S1, the level detection section 7 detects the received signal level based on the intermediate frequency signal level in the FM detection section 3, and this detection output is sent to the controller 10.
At the same time, the multipath interference detection unit 12 outputs N
The presence or absence of multipath interference is detected from the output section of K4, and the result of the presence or absence is output to the controller 10.

As a result, the controller 10 records the received signal level of the broadcasting station currently being received and the presence or absence of multipath detection in the AF memory 10.
1 and the process moves to the next step $2.

In this step S2, the controller 10 controls the AF
AF data is selected from the memory 11, a frequency division ratio is set in the PLL circuit 6, and the PLL circuit 6 causes the front end 2 to select a channel based on the frequency division ratio setting.

As a result, when the front end receives a new AF station, the received signal level of this AF station will be the same as above,
It is detected by the level detection section 7. This detection result is output to the controller 10.

In step S3, the controller 10 determines whether the received signal level of the AF station exceeds the received signal level of the original AF station.

As a result of this judgment, if the received signal level of the original AF station is exceeded, that is, if the new AF station optical reception signal level is the original AF station optical reception signal level, then Y in step S3 is determined.
Proceed to step S4 from the ES side.

In this step $4, the controller 10 returns the original A
At the receiving station of the F station, it is determined whether or not multipath interference is detected. If no multipath interference is detected, the process moves from the No side of step S4 to step S5, and in this step S5, the new AF The reception station of the station determines whether there is multipath interference.

As a result of this determination, if it is determined that there is no multipath interference, reception from the AF station is continued in step S7. That is,
This means that the reception has been switched to the reception station of the next new AF station.

In other words, when switching to the next new AF station reception station, the reception signal level of the new AF station exceeds the reception signal level of the original AF station reception station in step S3, and the original AF station reception station is switched to the original AF station reception station in step S4. If there is no multipath interference in the received signal of the receiving station of the new AF station and there is no multipath interference in the received signal of the receiving station of the new AF station in step S5, the receiving station of the next new AF station is Reception is switched.

Also, in step S4, if there is multipath interference in the received signal of the receiving station of the original AF station, step S4
The process then proceeds to step S7, and the process switches to receiving the next new AF station.

Such switching control of the next new AF station to the receiving station is performed by the controller 10 changing the frequency division ratio setting of the PLL circuit 6, and the PLL circuit 6 controlling the tuning operation of the front end 2. be exposed.

Next, a case will be described in which the receiving station is not switched to a new AF station.

In this case, in step S3, if the received signal level of the receiving station of the new AF station is lower than the received signal level of the receiving station of the original AF station, the process moves from the No side of step S3 to step S6, Return to reception at the original AF station receiving station.

Also, in step S5, if there is multipath interference in the received signal of the receiving station of the new AF station, the process moves from the YES side of step S5 to step S6, and the receiving station of the original AF station receives the signal. Return to

In the above embodiment, the received signal level of the receiving station is compared one by one for the AF stations, but all or some of the frequencies in the AF memory 11 are checked continuously and the best station is selected. It is clear that similar effects can be obtained when switching to .

In addition, in the above embodiment, automatic tuning control is performed based on the received signal level and the presence or absence of multipath interference. However, in addition to the above received signal level and presence or absence of multipath interference, network Automatic tuning of the RDS receiver may be controlled by determining whether the (PI) matches or does not match.

〔Effect of the invention〕

As described above, according to the present invention, when automatically tuning from an AF station receiving station to a new AF station receiving station, a new AF station is selected.
When the received signal level of the receiving station of the station is lower than the received signal level of the receiving station of the original AF station, or when the received signal level of the receiving station of the new AF station is lower than the received signal level of the receiving station of the original AF station. If the received signal at the receiving station of the original AF station has at least no multipath interference and the received signal at the receiving station of the new AF station has at least multipath interference, then Since the reception is switched, even if the received electric field level is good, switching to a station where multipath interference is occurring can be prevented, and a good reception state can be maintained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an automatic channel selection control device for an RDS receiver according to the present invention, and FIG. 2 is a flowchart showing the execution procedure of the controller in the same embodiment. 1... antenna, 2... front end, 3...
FM detection section, 4...NK, 5...MPX demodulation circuit,
6...PLIJ]il, 7...Level detection section, 8.
...Band pass filter, 9...RDS decoder, 1
0...Controller, 11...AF memory, 12.
...Multipath interference detection section. Procedural amendment (voluntary)

Claims (1)

[Claims] A front end capable of receiving RDS broadcast waves including frequency information codes and network recognition codes of the same network station group, having a function of selecting the same network stations, and outputting an intermediate frequency signal, and a tuning operation of this front end. A phase-locked loop circuit in which a frequency division ratio is set to perform
an FM detection section that performs detection, a multiplex demodulation circuit that demodulates the output of the FM detection section and outputs an audio signal, and a level detection section that receives the output of the FM detection section and detects the received signal level; an RDS decoder that converts the output of the FM detection section into predetermined distinguishable data;
a multipath interference detection section that detects multipath interference from the signal output from the FM detection section; and a multipath interference detection section that detects multipath interference from the signal output from the FM detection section; It has a built-in frequency information code memory that maintains the presence or absence of path interference and stores frequency information code data for one or more stations, and the received signal level of the current receiving station is higher than the received signal level of the original receiving station. When the multipath interference detection unit detects at least multipath interference at the original receiving station, and at least multipath interference is detected at the current receiving station, and at least multipath interference at the original receiving station is detected. When interference is detected and when the received signal level of the current receiving station is greater than the received signal level of the original receiving station and there is at least multipath interference at the original receiving station, the next new receiving station is selected. The frequency division ratio setting control of the phase-locked loop is performed so that the above-mentioned current receiving station's received signal level is lower than the received signal level of the original receiving station, and when the above-mentioned current receiving station receives An automatic channel selection control device for an RDS receiver, comprising: a controller that controls the frequency division ratio setting of the phase-locked loop circuit so that reception is switched to the original receiving station when path interference is detected.