JP2958933B2 - Radio data system receiver with IF band switching - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio data system receiver with IF band switching, and more particularly to an IF capable of performing stable radio data system data confirmation in a short time.
The present invention relates to a radio data system receiver with band switching. [0002] 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 wait process is performed at intervals of 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 intensity (signal meter) Vs currently being received.
Is lower than the search start electric field strength Va,
If it has decreased, in step S3, it waits until all AF search start conditions other than the electric field strength are satisfied. Here, if it is confirmed that all the conditions are satisfied, mute (MU)
TE), the alternative station is received (AF station reception) according to the AF list (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 signal returns to the original frequency and is received (step S).
6). When Vs is larger than Vb, whether or not the substitute station is really correct is checked based on the PI code (step S8).
Thereafter, the mute is released after a lapse of the time when the audio output is stabilized, the audio is output, and the process returns to the step S1. [0003] The conventional IF as described above
In the receiver with band switching, the adjacent interference detection unit malfunctions due to noise at the time of detuning or the like 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 narrow, the demodulation sensitivity of the RDS is adversely affected, and it is difficult to confirm the RDS data in a short time. Accordingly, an object of the present invention is to provide an RDS receiving apparatus with an IF band switch capable of confirming stable RDS data in a short time even when temporarily switching to a narrow band IF due to a malfunction of an adjacent interference detection unit or the like. To provide machines. [0005] In order to solve the above-mentioned problems, a radio data system 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 has an adjacent interference. When a signal is received, the narrow band I
IF configured to extract the output from the F filter
In the radio data system receiver with band switching, when confirming the radio data system data, after muting the output audio signal, the IF filter section is switched to a broadband IF filter to confirm the radio data system data. It is configured to unmute. According to the present invention, there is provided a receiver having a wide band IF filter section and a narrow band IF filter section, and taking out an output from the narrow band IF filter when an adjacent interference signal is received. At the time of channel selection, the wideband IF filter is forcibly selected while checking the data of the radio data system of the selected channel. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one 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 to an IF signal by a mixing process, and subjected to impedance matching and gain adjustment by the buffer amplifiers 2 and 3. , Are input to the wideband IF filter 4 and the narrowband IF filter 5 via the buffer amplifiers 2 and 3. 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 output a wideband IF signal.
One of the outputs of the filter 4 and the narrow-band IF filter 5 is selectively output. A 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
When the adjacent interference detection unit 8 detects noise around 100 KHz, for example, and reaches a certain noise level, it sends a control signal to the band switching unit 6 to selectively output the output of the narrow band IF filter 5. The detection output from the detection unit 7 is reduced in noise components by a noise canceller 9, demodulated by a stereo demodulation unit (MPX) 10, and adjusted in volume (VO).
L) After the sound volume adjustment in the section 11 and the mute processing in the mute section 12 are performed, the amplified
Output from P. The RDS data is demodulated by an RDS demodulation unit 14, and a detection output from the detection unit 7 is output by a synchronization unit 15.
RDS data group synchronization and error correction processing are performed, and the RDS data is sent to the microprocessor 16. The microprocessor 16 has a ROM and an RA.
M, operates according to a program stored in the ROM, receives a signal meter output from the detection unit 7,
A band control signal is transmitted to the band switching unit 6, a mute (MUTE) control signal is transmitted to the mute unit 12, and a signal for performing a tuning operation with the tuning system unit 17 having a PLL configuration is transmitted and received. FIG. 2 is a flowchart showing the operation of the embodiment of the present invention, and particularly shows a processing procedure at the time of an AF search. 2, processing blocks denoted by the same reference numerals as those in FIG. 3 indicate processing blocks that perform the same processing. Similar to the operation of the conventional RDS receiver of FIG. 3, search weight (step S1), comparison of Vs and Va (step S2), A
After determining that the F search condition is satisfied (step S3), mute and AF station reception processing (step S4), and comparing Vs and Vb (step S5), when it is determined that Vs is greater than Vb, the electric field strength is reduced. Since the result is OK, in order to check the PI code in step S8, the filter is forcibly switched to the wideband IF filter in advance (step S7), and the same PI code is checked in step S8 (step S8). After the PI code check is completed in step S8, the switching to the wideband IF filter is forcibly released, and when the audio output is stabilized, 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 described.
Of course, the same can be applied to DS data. In addition, seek (SEEK) and auto memory (AUT)
O MEMORY) After selecting a channel by operation, preset call, etc., while checking the PI code in a short time,
May be switched to the broadband side. As described above, according to the present invention, when it is necessary to check the radio data system data in a short time in the alternative frequency search of the radio data system receiver, the IF band becomes narrow. As a result, the demodulation sensitivity of the radio data system is deteriorated, and the radio data system data is not likely to be difficult to confirm, and the radio data system data can be surely confirmed within a short time while maintaining the superiority of 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 Broadband 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 Department

Claims (1)

(57) [Claims] It has a wide band IF filter section and a narrow band IF filter section,
La with IF band switching that is configured to take out the output from the narrow band IF filter when receiving the adjacent interference signal
When confirming the radio data system data at the geo data system receiver , the output audio signal
After the signal mute, the IF filter section
To confirm the radio data system data
After the output radio data system receiver with IF band switching, characterized in that to release the muting of the audio signal.