JPH06232776A - Rds receiver with if band changeover - Google Patents

Abstract

PURPOSE:To confirm RDS data stably in a short time by selecting forcibly a broad band filter while RDS data of a channel selection destination are checked at channel selection at AF check time or the like. CONSTITUTION:An RF signal from an antenna is converted into an IF signal at a front end 1 and inputted to a broad band IF filter 4 and a narrow band IF filter 5. A band changeover section 6 selects and outputs either of outputs from the filters 4, 5 based on a band control signal from a microprocessor 16 and a control signal from an adjacent disturbance detection section 8. When the AF search start condition is established and an electric field strength of a substitute station is larger than a receptible electric field strength, the microprocessor 16 selects forcibly the filter 4 to confirm a PI code. After the end of check of the PI code, the changeover to the filter 4 is released and the usual operation is executed. Thus, the possibility of reaching a state of difficulty in confirming RDS data is precluded and the data are confirmed in a short time.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RDS with IF band switching.
The present invention relates to a receiver, and more particularly to an RDS receiver with IF band switching capable of confirming stable RDS data in a short time. 2. Description of the Related Art FIG. 3 shows a conventional RDS with IF band switching.
The flowchart of the operation at the time of AF search of the receiver is shown. In the figure, first, a search weight process is performed to set a search interval so that the AF search is not performed in an unnecessarily short time (step S1), and in step S2, the electric field strength (signal meter) Vs currently received is calculated.
Is lower than the search start electric field strength Va,
If it has fallen, in step S3, it waits until all the AF search start conditions other than the electric field strength are satisfied. Here, if it is confirmed that all are satisfied, the mute (MU
TE) is applied to receive the alternative station according to the AF list (AF station reception) (step S4), and it is determined whether the electric field strength Vs of the alternative station is larger than the receivable electric field strength Vb (step S5). When it is determined that Vs is smaller than Vb, the original frequency is returned to the reception (step S).
6). When Vs is larger than Vb, it is checked based on the PI code whether or not the alternative station is really the correct station (step S8).
After that, the mute is released after a lapse of time when the voice output is stabilized, the voice is output, and the process returns to step S1. [0003] The conventional IF as described above.
In the receiver with band switching, the adjacent interference detection unit malfunctions due to noise during detuning during the channel selection operation, and the IF band is temporarily switched to the narrow band side. On the other hand, in the RDS receiver, if the IF band is narrowed, the demodulation sensitivity of the RDS is adversely affected, and it is difficult to check the RDS data in a short time. Therefore, an object of the present invention is to enable stable confirmation of RDS data in a short time even when the narrow band IF is temporarily switched due to an erroneous operation of the adjacent interference detecting section or the like, and RDS reception with IF band switching. To provide a machine. In order to solve the above-mentioned problems, an RDS receiver with IF band switching according to the present invention has a wide band IF filter section and a narrow band IF filter section, and is capable of removing adjacent interference signals. RD with IF band switching configured to extract the output from the narrow band IF filter when received
In the S receiver, in the presence of receivable RDS data,
It is configured to forcibly and selectively switch the wideband IF filter while checking the RDS data of the tuning destination at the time of tuning such as AF checking. According to the present invention, a receiver having a wide band IF filter section and a narrow band IF filter section for extracting an output from the narrow band IF filter when an adjacent interfering signal is received,
During the channel selection, such as when checking, the broadband IF filter is forcibly selected while checking the RDS data of the channel selection destination. Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an RDS receiver with IF band switching according to the present invention.
The RF signal received via the antenna ANT is tuned and amplified by the front end (F / E) 1, converted into an IF signal by the mixing process, and impedance matching and gain adjustment are performed by the buffer amplifiers 2 and 3. , Through the buffer amplifiers 2 and 3 to the wideband IF filter 4 and the narrowband IF filter 5. The band switching unit 6 uses the band control signal from the microprocessor 16 and the control signal from the adjacent interference detection unit 8 to generate a wide band IF.
Either the output of the filter 4 or the narrow band IF filter 5 is selectively output. The detection unit (IF / DET) 7 amplifies the IF signal from the band switching unit 6 and a signal meter (S meter).
Detection and detection processing. The detection output from the detection unit 7 is
For example, when a noise around 100 KHz is detected by the adjacent interference detection unit 8 and the noise level becomes constant, a control signal is sent to the band switching unit 6 to selectively output the output of the narrow band IF filter 5. The noise output of the detection unit 7 is reduced by the noise canceller 9 and demodulated by the stereo demodulation unit (MPX) 10 to adjust the volume (VO
L) The volume is adjusted in the unit 11 and the mute process is performed in the mute unit 12, and then amplified by the amplifying unit 13 to produce the speaker S.
It is output from P. From the detection output from the detection unit 7, RDS data is demodulated in the RDS demodulation unit 14, and in the synchronization unit 15,
The RDS data group synchronization and error correction processing is performed and the RDS data is sent to the microprocessor 16. Microprocessor 16 includes ROM and RA
It has M, operates according to the program stored in ROM, receives the signal meter output from the detection unit 7,
The band control signal is sent to the band switching unit 6, the mute (MUTE) control signal is sent to the mute unit 12, and the signal for performing the tuning operation is exchanged with the tuning system unit 17 having the PLL structure. FIG. 2 shows an operation flowchart of the embodiment of the present invention, and particularly shows a processing procedure at the time of AF search. In FIG. 2, processing blocks denoted by the same reference numerals as those in FIG. 3 indicate processing blocks that perform similar processing. Similar to the operation of the conventional RDS receiver shown in FIG. 3, search weight (step S1), comparison of Vs and Va (step S2), A
After it is determined that the F search condition is satisfied (step S3), the mute and AF station reception processing (step S4), and the comparison between Vs and Vb (step S5), it is determined that Vs is larger than Vb, the electric field strength is Since it is OK, in order to perform the PI code check in step S8, the wideband IF filter is forcibly switched in advance (step S7), and the same PI code in step S8 is confirmed (step S8). After the PI code is checked in step S8, the switching to the wideband IF filter is forcibly released, and when the audio output is stable, the mute is released and the audio is output (step S10). In the flowchart of FIG. 2, only the PI code as the RDS data is explained, but other R codes are used.
Of course, the same can be applied to the DS data. In addition, seek (SEEK) and auto memory (AUT
(O MEMORY) operation, preset calling, etc.
May be switched to the broadband side. As described above, according to the present invention, when it is necessary to check the RDS data in a short time in the AF search of the RDS receiver, the IF band becomes narrow due to a malfunction, and the RDS becomes narrow. The demodulation sensitivity is deteriorated, there is no fear of falling into a state where it is difficult to confirm the RDS data, and the RDS data can be surely confirmed within a short time while maintaining the superiority of the IF band switching.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration block diagram of an embodiment of an RDS receiver with IF band switching according to the present invention. FIG. 2 is a flowchart showing an operation processing procedure in the embodiment of the present invention. FIG. 3 is a flowchart showing an operation processing procedure in a conventional example. [Explanation of symbols] 1 Front end 2, 3
Buffer amplifier 4 Wide band IF filter 5 Narrow band IF filter 6 Band switching unit 7 Detection unit 8 Adjacent interference detection unit 9 Noise canceller 10 Stereo demodulation unit 11 Volume control unit 12 Mute unit 13 Amplification unit 14 RDS demodulation unit 15 Synchronization unit 16 Microprocessor 17 Tuning system section

Claims (1)

A wideband IF filter section and a narrowband IF filter section are provided.
IF band switching R configured to extract the output from the narrow band IF filter when receiving an adjacent interfering signal
In the DS receiver, in the presence of receivable RDS data, the wideband IF filter is forcibly and selectively switched while checking the RDS data of the tuning destination at the time of tuning such as AF checking. RDS receiver with IF band switching.