JP3969393B2 - Receiving machine - Google Patents

Description

  The present invention relates to a receiver having a function of moving to an alternative frequency station that is broadcasting the same broadcast content when the reception state of a receiving broadcast station is deteriorated.

  For example, in a radio receiver mounted on a vehicle or the like, in particular, an RDS (Radio Data System) receiver, for example, when the reception state deteriorates far away from a currently receiving broadcast station, an AF (Alternative Frequency: alternative frequency) ) According to the list and the AF reception history, it has a function of moving to an AF station (alternative frequency station) with good reception of other frequencies of the same broadcast content. Each broadcasting station transmits RDS data including frequency data of network stations adjacent to the periphery of the service area of the own station as an AF list.

  As shown in FIG. 4, a conventional RDS receiver includes a PLL receiving circuit 2 that receives a broadcast signal input from an antenna 1, a muting circuit 3 connected to the PLL receiving circuit 2, a microcomputer (hereinafter referred to as a microcomputer) 4, and , An RDS data demodulating circuit 5 and a receiving sensitivity detecting circuit 6 for demodulating an RDS data signal including RDS data from a broadcasting station connected to the PLL receiving circuit 2, and a memory 7 for storing the RDS data signal from the RDS data demodulating circuit 5. Etc.

  The RDS receiver first mutes the muting circuit 3 controlled by the microcomputer 4 to select the AF station so that unpleasant noise is not heard when checking the reception state of the AF station. The N value data is transmitted to the PLL circuit in the PLL receiving circuit 2, and after the tuning frequency of the PLL receiving circuit 2 is changed to the receiving frequency of the AF station, the receiving state of the AF station is viewed by looking at the receiving state of the AF station. If the reception level is better, the frequency of the AF station is set to the reception state, and if it is worse, the N value is returned so as to receive the frequency of the current broadcast station that has been received so far, and muting is removed (FIGS. 5 and 5). 6). (For example, refer to Patent Document 1).

As described above, a system for checking a different frequency by performing a short muting while receiving a radio may be other than the RDS receiver.
JP-A-11-97983

  In the RDS receiver, if the muting time applied when checking the reception state of the AF station is long, the sound is interrupted and the listener is uncomfortable. Conventionally, since the N-value data of the AF station is transmitted to the PLL circuit of the PLL receiving circuit 2 after muting is applied, the AF station reception is delayed and the muting time becomes longer, giving the listener unpleasant feeling.

  The present invention has been made in view of the above-described problems of the conventional RDS receiver, and provides a receiver capable of shortening the muting time when checking the reception status of the AF station of the receiver and performing good radio reception. With the goal.

The invention according to claim 1 is an electronic tuning means for changing the tuning frequency by changing the N value of the PLL circuit, and replacing the N value by muting during broadcast reception of a certain broadcasting station. in the receiver having a function to check the reception state of the received frequency station alternate frequency station, and latch means for latching the N-value data for receiving the pre-SL alternative frequency stations, latching means the previous SL N value data N-value data transmitting means for transmitting to, a muting circuit for detecting the zero-crossing of the audio signal after the transmission of the N-value data and applying the muting, and receiving the zero-crossing detection signal and latched by the latch means And a control means for outputting the N value to the frequency divider of the PLL circuit, and the muting time is shortened by N value transmission .

According to a second or third aspect of the present invention, there is provided an electronic tuning means for changing a tuning frequency by changing an N value of a PLL circuit, and obtaining the alternative frequency station data during broadcast reception and muting the data. Te FM receiver or RDS receiver odor and a receiving alternative frequencies station by changing the value function for checking the reception status of alternative frequency stations, latches the N value data for receiving the pre-SL alternative frequency station and latch means, the N value data transmitting means for transmitting a pre-Symbol N value data to the latch means, after the transmission of the N-level data, and the muting circuit for detecting the zero crossing of the audio signal applied to the muting, the zero-crossing and control means for outputting the N value latched in said latch means in response to a signal detecting the frequency divider of the PLL circuit, N value transmitted partial muting time Contraction and, after serial alternative frequency tuning features that you receive the previous frequency receiver or said alternative frequency station by checking the result of the reception status.

  According to the first to third aspects of the present invention, since the latch means is provided and the N-value data transmission for receiving the alternative frequency station is executed by the latch means before the muting is performed, the muting time Can be shortened by N value transmission time.

  According to the present invention, since the alternative frequency station data transmission for changing the N value of the PLL is executed to the latch means before muting is performed, the muting time is reduced by the N value data transmission time. To the extent that the listener cannot discriminate. Therefore, it is possible to listen to the radio broadcast in a good reception state at any time during reception.

  FIG. 1 shows a block diagram of an RDS receiver according to an embodiment of the present invention. 1, a tuner 12 is an electronic tuning tuner, and receives a voltage for controlling a VCO (Voltage Controlled Oscillator) 24 output from an LPF (Low Pass Filter) 23 of the PLL circuit 20 from the antenna 11 as a channel selection voltage. An FM broadcast signal is received from the signal. The RF amplifier 13 amplifies the FM broadcast signal, the mixer circuit 14 converts the FM broadcast signal into an intermediate frequency signal using the oscillation frequency signal of the VCO 24 of the PLL circuit 20 as a local oscillation signal, and the IF amplifier 15 converts the intermediate frequency signal. Amplify.

  The FM detection circuit 16 detects the intermediate frequency signal, and the stereo decoder 17 outputs a stereo audio signal (hereinafter simply referred to as an audio signal) from the detected signal. The muting circuit 18 includes a zero-cross detection circuit. When the muting 0N control signal transmitted from the microcomputer 30 is received, the muting circuit 18 detects the zero-crossing of the audio signal and turns on the mute. Further, when the AF station reception status check result described later is satisfactory, when a mute OFF control signal transmitted from the microcomputer 30 is received, a zero cross is detected and the mute is turned off.

  The PLL circuit 20 has a frequency division ratio N set by the input of N-value data, and a frequency comparison circuit 21 that divides the oscillation frequency of the VCO 22, a phase that compares the phase of the output signal of the oscillator 25 and the output signal of the frequency division circuit 21. The LPF 24 and the VCO 22 whose oscillation frequency is controlled by the output voltage of the LPF 24 are input to outputs of the comparison circuit 23 and the phase comparison circuit 23.

  The latch circuit 26 is connected between the microcomputer 30 and the frequency dividing circuit 21 and receives an AF search bit transmitted from the microcomputer 30 and N value (PLL circuit 20 frequency dividing value) data of the AF station and latches the N value. The muting circuit 18 detects the zero crossing of the audio signal and then outputs the N value latched under the control of the microcomputer 30 to the frequency dividing circuit 21. Reference numeral 27 denotes a reception sensitivity detection circuit, 28 denotes an RDS demodulation circuit, and a memory 29 stores RDS data demodulated by the RDS demodulation circuit 28, an AF station list, and the like.

  The microcomputer 30 controls the AF search operation and the like of the RDS receiver 10 according to a processing routine written in a ROM (not shown).

  Next, the AF search operation of the RDS receiver 10 will be described with reference to the flowchart shown in FIG. 2 and the timing chart shown in FIG. While receiving a broadcast from a certain broadcast station (S11), the microcomputer 30 receives a signal from the reception sensitivity detection circuit 27 and determines whether or not the reception state of the current broadcast station has deteriorated (S12). For example, if the reception state of the receiving broadcast station deteriorates due to the movement of the vehicle on which the RDS receiver 10 is mounted, and the result of the reception state deterioration determination of the current broadcast station becomes YES, the microcomputer 30 stores in the memory 29. An AF search bit of an AF station that is broadcasting the same as a current broadcast station and N-value data of the AF station list (or AF reception history) are transmitted to the latch circuit 26 (S13).

  After that, the microcomputer 30 transmits a mute ON control signal to the muting circuit 18, and the muting circuit 18 that has received the mute ON control signal detects a zero cross of the audio signal output from the stereo decoder 17 and sets the audio signal as mute ON. The mute is turned on (S14). When the zero cross is detected, the latch circuit 26 receives the transmission signal from the microcomputer 30 and outputs the N value of the AF station that has been latched to the PLL circuit 20. The value instantly changes to the N value of AF station selection, and the AF station is received (S15). The microcomputer 30 receives the signal from the reception sensitivity detection circuit 27 and checks the reception status of the AF station. (S16).

  If the result of checking the reception status of the AF station is worse than the reception status of the current broadcast station, the microcomputer 30 returns the N value of the AF station to the N value of the current broadcast station and tunes it to the frequency of the current broadcast station. Is transmitted to the muting circuit 18 to detect the zero cross of the audio signal, and when the zero cross is detected, the muting circuit 18 receives the current broadcast station as mute OFF (S18). In this case, the muting time from mute ON to mute OFF is about 6 ms (FIG. 3A).

  If the check result of the AF station reception status is better than the current broadcast station reception status, the microcomputer 30 transmits to the muting circuit 18, and when the muting circuit 18 detects the zero cross of the audio signal, the AF station is set to mute OFF. Receive (S17). In this case, the muting time from mute ON to mute OFF is about 4.5 ms (FIG. 3B).

  On the other hand, the conventional RDS receiver (FIG. 4) does not include the latch circuit 8 of FIG. Then, since the AF search operation is performed according to the flow shown in FIG. 5, if the determination result of the reception state deterioration of the broadcasting station in S22 (S22) is YES, the muting circuit 18 detects the zero crossing of the audio signal and sets the mute ON. After the audio signal of the broadcasting station is muted, the AF search bit and the AF station N value data are transmitted from the microcomputer 30 to the PLL circuit 20 (S24, S25). Therefore, as shown in FIG. 6, it takes time (N value transmission time) from mute ON to tuning to the AF frequency.

  Therefore, the muting time when the reception status check result of the AF station in S26 is worse than the reception status of the current broadcasting station is about 7 ms (FIG. 6A), and the reception status check of the AF station is now The muting time when it is better than the reception situation of the broadcasting station is about 5.5 ms (FIG. 6B).

  According to the present invention, the time corresponding to the N value transmission time (time of S24) required from the mute ON of FIG. 6 to the tuning to the AF frequency can be eliminated, so that the muting time is about 1 ms. It was shortened. As a result, an RDS receiver that can be brought closer to a muting time of about 3 ms that cannot be discriminated by human ears, and that does not feel the sound cut off due to muting during the AF search operation is obtained.

  In FIG. 1, the muting circuit 18 is provided in the audio circuit unit, but may be provided in the tuner unit. Further, the stereo decoder 17 can be a monaural decoder. The latch circuit 26 only needs to have an equivalent function.

  Although the RDS receiver has been described above, the present invention can be applied to an electronic tuning receiver in which the tuner changes the N value of the PLL circuit and performs tuning even without the RDS function. For example, by storing the AF station N value list in the memory 29 in advance, it is possible to execute the AF search operation as in FIG. In the case of FM multiplex broadcasting, alternative frequency station data can be obtained by receiving FM multiplex broadcasting. The present invention is not limited to an RDS receiver, and can be applied to an electronic tuning receiver that performs tuning by changing the N value of a PLL circuit.

The block diagram of the RDS receiver which concerns on embodiment. The flowchart of AF search operation | movement which concerns on embodiment. 6 is a timing chart of an AF search operation according to the embodiment. The block diagram of the RDS receiver which concerns on a prior art example. 10 is a flowchart of an AF search operation according to a conventional example. 10 is a timing chart of an AF search operation according to a conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... RDS receiver, 12 ... Tuner, 14 ... Mixer, 16 ... FM detection circuit, 17 ... Stereo decoder, 18 ... Muting circuit, 20 ... PLL circuit, 26 ... Latch circuit, 27 ... Reception sensitivity detection circuit, 28 ... RDS data demodulating circuit, 29 ... memory, 30 ... microcomputer.

Claims (3)

Electronic tuning means for changing the N value of the PLL circuit to change the tuning frequency, and muting during the broadcast reception of a certain broadcast station, changing the N value to receive the alternative frequency station and receiving the alternative frequency station In a receiver having a function of checking reception status,
And latch means for latching the N-value data for receiving the pre-SL alternative frequency stations,
And N value data transmitting means for transmitting a pre-Symbol N value data to the latch means,
A muting circuit for detecting a zero crossing of an audio signal and applying the muting after transmitting the N-value data;
Control means for receiving the zero-cross detection signal and outputting the N value latched by the latch means to the frequency divider of the PLL circuit;
The receiver is characterized in that the muting time is shortened by N value transmissions . Electronic tuning means for changing the N frequency of the PLL circuit to change the tuning frequency, and obtaining the alternative frequency station data during FM multiplex broadcast reception, muting and changing the N value to receive the alternative frequency station In an FM receiver having a function of checking the reception status of an alternative frequency station,
And latch means for latching the N-value data for receiving the pre-SL alternative frequency stations,
And N value data transmitting means for transmitting a pre-Symbol N value data to the latch means,
A muting circuit for detecting the zero crossing of an audio signal and applying the muting after transmitting the N-value data;
Control means for receiving the zero-cross detection signal and outputting the N value latched by the latch means to the frequency divider of the PLL circuit;
The FM receiver is characterized in that the muting time is shortened by N value transmissions, and after receiving the alternative frequency tuning, the previous frequency reception or the alternative frequency station is received according to the reception status check result. Tuning means for changing the N frequency of the PLL circuit to change the tuning frequency, and obtaining the alternative frequency station data during the broadcast reception of the broadcasting station transmitting the RDS data and muting it to change the N value In the RDS receiver having the function of receiving the alternative frequency station and checking the reception status of the alternative frequency station,
And latch means for latching the N-value data for receiving the pre-SL alternative frequency stations,
And N value data transmitting means for transmitting a pre-Symbol N value data to the latch means,
A muting circuit for detecting a zero crossing of an audio signal and applying the muting after transmitting the N-value data;
Control means for receiving the zero-cross detection signal and outputting the N value latched by the latch means to the frequency divider of the PLL circuit;
An RDS receiver comprising : reducing the muting time by N value transmission, and receiving the previous frequency reception or the alternative frequency station according to the reception status check result after the alternative frequency tuning .

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