JPH07221660A - Rds receiver - Google Patents

Abstract

PURPOSE:To enable a right follow-up operation, to speed up an operation and to unnecessitate large capacity of a memory by making the electric field intensity information of an AF code station to a low value by a lowring means when adjacent disturbance is detected. CONSTITUTION:The electric field intensity of the broadcasting received by an FM tuner part 1 is inputted as S meter in a CPU 4, a digital conversion is performed for the intensity at the inside of the CPU 4 and the electric field intensity is checked. The RDS data received by an FM tuner part 1 is decoded in a RDS decoder 5 and the data is inputted as RDS data in the CPU 4. When the RDS data is detected, the RDS decoder 5 raises the RDS flag, transmits a RDS presence or absence signal to a transistor Q and turns on the transistor Q when the RDS data is not detected. Further, the transistor Q grounds or does not ground the output of the S meter from the FM tuner part 1 by the turning on/off of the transitor Q and the output of the S meter is lowered when the RDS data is not detected.

Description

Detailed Description of the Invention

[0001]

This invention relates to RDS radio receivers.

[0002]

2. Description of the Related Art RDS receivers are widely used in Europe and the like and have an AF switching function of updating and following the same program of different frequencies as it moves.
That is, the RDS data that is multiplexed and transmitted from the broadcasting station includes AF list data that is a list of different frequency groups broadcasting the same program. RD
The S receiver receives the target frequency from this AF list for a moment, checks the electric field strength with a signal meter (S meter), and selects a frequency with a stronger electric field strength as compared with the currently receiving station. Is configured to select. However, in such an RDS receiver, S
Since the reception band output from the meter is wide, there is a problem that when interference such as adjacent interference occurs, even if the electric field strength of a frequency is weak, it is judged to be strong due to the influence of the interference and the frequency is switched to that frequency. . Also, when adjacent stations increase in interference with the receiving station, it is determined that the electric field strength of the receiving station is strong, and it becomes impossible to switch to another station in the AF list with a stronger electric field strength. There was a problem. In order to solve such a problem, for example, a method disclosed in JP-A-1-208030 is known. According to this method, a station in the AF code list and a station of 100 kHz adjacent to the station are received, and the electric field strength of the station in the AF code list is corrected based on the electric field strength of the adjacent station.

[0003]

However, in the above-mentioned conventional method, it is necessary to receive the adjacent stations before and after the station in the AF code list, which has a disadvantage that it takes time and the operation becomes slow. Further, it is necessary to store information of a large number of stations, and there is a problem that a large memory capacity is required. The present invention aims to solve the above-mentioned problems of the prior art.

[0004]

In order to achieve the above object, the RDS receiver of the present invention is based on one or more AF codes included in transmission data of a radio data system,
In the RDS receiver equipped with the function of automatically selecting the broadcasting station with the best electric field strength level among the same program broadcasting stations,
Automatic channel selection means for automatically selecting the same program based on the F code, adjacent channel interference detection means for detecting the presence or absence of adjacent channel interference of the AF code station received at the time of the automatic channel selection, and AF detection for the adjacent channel interference. A basic feature is that the lowering means reduces the electric field strength information of the code station to a low value.

[0005]

The automatic tuning means performs the same program automatic tuning based on the AF code, and at the time of the automatic tuning, the presence or absence of adjacent interference of the received AF code station is detected by the adjacent interference detecting means. When the adjacent interference is detected, the field strength information of the AF code station is set to a low value by the lowering means.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment shown in FIG. 1, adjacent interference detection is performed by detecting whether or not the RDS demodulation signal is available. RDS is FM
This is a broadcasting system in which a 57 kHz pilot signal is used for modulation and pulse modulation is multiplexed, and since the pilot signal is a high tone of 57 kHz, the demodulation frequency band must be wide. Generally, the filter characteristic of the demodulation band is wide at a place where the signal strength is strong, and tends to become narrower as the signal strength becomes weaker. Therefore, the demodulation capability of RDS data becomes impossible when the signal becomes weak to some extent. If there is adjacent interference or interference in the received frequency, AGC
Thus, the sensitivity is suppressed and the signal strength can be deteriorated. By detecting the availability of the RDS demodulation signal using the above two characteristics, it becomes possible to detect the presence or absence of the interfering station in a pseudo manner.

A specific configuration will be described with reference to FIG. FM
The broadcast received by the tuner unit 1 is converted into sound by the speaker and output via the audio control unit 2 and the audio amplifier unit 3. The electric field strength of the broadcast received by the FM tuner unit 1 is input to the CPU 4 as an S meter, and is digitally converted inside the CPU 4 to check the electric field strength. Further, the RDS data received by the FM tuner unit 1 is decoded by the RDS decoder 5 and is converted into RDS data by the CPU 4
It is designed to be input to. RDS decoder 5 is R
When DS data is detected, RDS flag is set and RD
An S presence / absence signal is sent to the transistor Q, and the transistor Q is turned on when RDS data is not detected. The transistor Q turns the S-meter output from the FM tuner unit 1 to ground or non-ground by turning it on and off, and is configured to lower the S-meter output when RDS data is not detected.

The CPU 4 is adapted to perform an AF switching operation for switching to the same program broadcasting station having a higher electric field strength based on the AF list included in the RDS data by a predetermined program.

In the above configuration, even if the S meter value becomes large due to the influence of adjacent interference, if it is judged that there is adjacent interference depending on whether RDS data can be detected or not, the transistor Q is turned on to cause the S interference. The meter value is forced to 0. Therefore, the correct follow-up operation is performed. Also,
Since it is not necessary to receive a station adjacent to the AF code list station as in the conventional technique, the operation is fast and a large capacity memory or the like is not required.

AFC (Auto Frequency Control) is shown in FIG.
An example will be shown in which adjacent interference detection is performed by using. The FM detection has a function of detecting a tuning frequency that is stable with respect to the reception frequency by AFC. In the FM, a frequency shift of ± 75 kHz occurs at 100% modulation around the reception frequency, but the center frequency and the reception frequency are always matched by AFC. If there is an adjacent jamming station, and the modulation degree of the adjacent jamming station becomes deeper, the frequency deviation of the adjacent jamming station also affects the reception frequency, which causes deviation in the frequency deviation of the reception frequency. . At this time, the frequency regarded as the center frequency by the AFC shifts, so that the voltage output of the AFC changes. Therefore, if the change in the voltage output of the AFC is detected, the adjacent interfering station can be detected.

This will be described in detail with reference to FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. The AFC voltage output from the FM tuner unit 1 and the reference voltage Vref are output to the voltage comparator 11, where the AFC voltage and the reference voltage are compared, and if the difference is equal to or more than a predetermined value, a signal for detecting an adjacent interfering station is output. It is adapted to be output to the transistor Q. The signal turns on the transistor Q, and the S-meter signal from the FM tuner unit 1 is forced to 0.
It is said that

The operation of the embodiment shown in FIG. 2 will be described with reference to FIG. RDS reception is performed at reception frequency 50 (step 2
0), the RDS tracking operation is appropriately executed (step 2).
1). At this time, the voltage comparator 11 and the transistor Q perform the interrupt operation. That is, | Vref-AFC | is calculated in the voltage comparator 11 (step 22), and when the difference is equal to or larger than the predetermined value a, the output of the voltage comparator 11 becomes "H" (step 2).
3) and the transistor Q is turned on (step 2
4), the AD port of the CPU 4 is forced to "L" (step 25). Then, returning to the normal RDS tracking operation, the S meter voltage is sequentially compared from f0 to fn (steps 26 and 27), and the frequency is switched to a large S meter value (step 28).

In the above configuration, even if the S meter value becomes large due to the influence of adjacent disturbance, if it is determined that there is adjacent disturbance due to the change in the AFC voltage, the S meter value is turned on by turning on the transistor Q. Is forced to 0.
Therefore, the correct follow-up operation is performed. Further, unlike the prior art, it is not necessary to receive a station adjacent to the AF code list station, so that the operation is fast and a large capacity memory or the like is not required.

FIG. 3 shows an example in which adjacent interference is detected by using an AC component appearing in the S meter. It is known that when the degree of modulation of an adjacent interfering station exceeds a certain level, interfering noise occurs in the receiving station and sound distortion occurs. Further, it is known that in this state, interfering noise leaks to the S meter as an AC component. Therefore, it can be determined that there is adjacent interference by detecting the AC component appearing in this S meter.

This will be described in detail with reference to FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals. Only the AC component is extracted by the capacitor C from the S meter signal from the FM tuner unit 1, this is digitally converted by the A / D converter 10, and the transistor Q is turned on by the output from the A / D converter 10 to turn on the S meter. Signal 0
It is supposed to be. As described above, if there is adjacent interference, the interference noise of the AC component is mixed in the S meter signal, so this can be extracted by the capacitor C and the adjacent interference station can be detected by the A / D converter 10.

In the above-mentioned structure, the transistor Q is turned on when it is determined that there is adjacent interference due to the detection of the AC component of the S meter signal even if the S meter value becomes large due to the influence of adjacent interference. The S meter value is forced to 0. Therefore, the correct follow-up operation is performed.
Further, unlike the prior art, it is not necessary to receive a station adjacent to the AF code list station, so that the operation is fast and a large capacity memory or the like is not required.

[0017]

As described above, the RDS receiver of the present invention is included in the transmission data of the radio data system.
In an RDS receiver having a function of automatically selecting a broadcasting station having the best electric field strength level in the same program broadcasting station on the basis of one or more AF codes, automatic tuning means for automatically tuning the same program based on the AF code An adjacent interference detecting means for detecting the presence or absence of adjacent interference of the received AF code station during the automatic channel selection, and a lowering means for reducing the electric field strength information of the AF code station during the adjacent interference detection, Therefore, the correct follow-up operation is performed. Further, there is an effect that the operation is fast and a large capacity memory or the like is not required.

[Brief description of drawings]

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

FIG. 2 is a functional block diagram showing another embodiment of the present invention.

FIG. 3 is a functional block diagram showing still another embodiment of the present invention.

FIG. 4 is a flow chart for explaining the operation of the embodiment shown in FIG.

[Explanation of symbols]

1: FM tuner section, 2: Audio control section,
3: audio amplifier unit, 4: CPU, 5: RDS decoder, 10: A / D converter, 11: voltage comparator.

Claims (3)

[Claims] 1. An RDS receiver having a function of automatically selecting a broadcasting station having the best electric field strength level in the same program broadcasting station based on one or more AF codes included in transmission data of a radio data system, An automatic tuning means for automatically tuning the same program based on the AF code; an adjacent interference detecting means for detecting the presence or absence of adjacent interference of the received AF code station during the automatic tuning; An RDS radio receiver comprising: a lowering unit that lowers the electric field strength information of the code station. 2. An RDS receiver having a function of automatically selecting a broadcasting station having the best electric field strength level in the same program broadcasting station based on one or more AF codes included in transmission data of a radio data system, An automatic tuning means for automatically tuning the same program based on the AF code, a signal detecting means for detecting a change in the AFC signal during the automatic tuning, and a low value for the electric field strength information of the AF code station during the detection. An RDS radio receiver, comprising: 3. An RDS receiver having a function of automatically selecting a broadcasting station having the best electric field strength level in the same program broadcasting station based on one or more AF codes included in transmission data of a radio data system, An automatic tuning means for automatically tuning the same program based on the AF code, a detecting means for detecting an AC component of the S meter signal at the time of the automatic tuning, and a low electric field strength information of the AF code station at the time of the detection An RDS radio receiver comprising: a means for reducing the value.