JP3806615B2 - Receiving machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiver, and more particularly, to a receiver such as a radio equipped with an auto-tuning and manual tuning function for searching for broadcast radio waves and tuning (tuning) a desired broadcast station.
[0002]
[Prior art]
It has a channel selection device for receiving broadcast radio waves from a desired broadcast station by a receiver. This channel selection apparatus has an LC tank (resonance) circuit including an inductor (L) and a capacitor (C), and by changing the capacitor (or inductor), the resonance frequency is changed to the frequency of the desired broadcasting station. Tune and tune in. When tuning with such a receiver, there are an auto-tuning method for automatically capturing broadcast (frequency) radio waves and a manual tuning method for manually increasing / decreasing the capture frequency. The resonance frequency of the channel selection device is continuously changed (scanned) by auto or manual tuning. Then, after confirming that the channel selection display (TUNED) element is lit by the SD signal generated based on the M conversion process at the time of reception of the desired broadcast station, the frequency scan (change) is stopped. At this time, the presence / absence of the SD signal is confirmed. If “Yes”, the IF count is performed. After confirming the IF frequency, the output mute (silence state) is canceled and the broadcast is received.
[0003]
There is a possibility that the radio wave of the desired broadcast station becomes weak due to radio wave interference or interruption of broadcasting while the desired broadcast station is selected, and the SD signal becomes “None”, then the radio wave becomes strong and the SD signal becomes “Yes”. . In this case, the IF count is performed, and after confirming the IF frequency, the output mute is canceled and the broadcast is received.
[0004]
[Problems to be solved by the invention]
After the receiver selects the desired broadcast station, when the signal becomes weak and the lighting level of the channel selection display (TUNED) element is near the threshold (threshold), the SD signal changes from “none” to “present”. Count. Then, after confirming the IF frequency, the channel selection display (TUNED) element is turned on. At the same time, output mute is applied to prevent output noise during IF counting, and the output mute is released after the channel selection display (TUNED) element is turned on. Further, when this SD signal is repeatedly performed from “present” to “none” and “none” to “present” continuously, the output mute is applied to prevent the noise described above, or the output is not output or There was a problem that the output mute was not released easily.
[0005]
Therefore, in the prior art, an integrating circuit is inserted between the system IC and the microcomputer port in order to delay chattering of the SD signal. However, if the time constant of the integration circuit is increased, the frequency scan time approaches during the auto tuning operation, the channel selection operation cannot be performed, and the capture frequency is skipped.
[0006]
In the microcomputer program, after the channel selection operation, the IF signal is not counted even if the SD signal changes from “No” to “Yes” due to the strength of the radio wave, and the SD signal is changed from “Yes” to “No”, “No” to “No”. Even if continuously changed to “present”, the channel selection display (TUNED) element is made to follow from on to off and from on to off. Also, when the broadcasting station stops sending radio waves and the receiver is turned on before re-broadcasting, the channel selection operation is performed once, and the channel selection display (TUNED) element is turned off. Later, if the radio wave becomes stronger, the channel selection display (TUNED) element remains off.
[0007]
OBJECT OF THE INVENTION
An object of the present invention is to provide a receiver that solves the above-described problems of the prior art and avoids the fact that the output mute is not canceled due to chattering of the SD signal and is mistaken for a failure.
[0008]
[Means for Solving the Problems]
Receiver of the present invention includes a tuner circuit that selects a signal received from the antenna, possess a PLL (phase locked loop) circuit for supplying a tuning signal to said tuner circuit, upon reception of the desired broadcast station from the tuner circuit An SD detection circuit for detecting the generated SD signal, an IF count circuit for receiving IF signals from the tuner circuit and counting IF frequency data, the SD signal from the SD detection circuit, and a count from the IF count circuit With a control circuit that controls the channel selection operation by determining the channel selection state based on the value, in the receiver that performs the auto or manual tuning channel selection operation,
When the tuner circuit performs the auto or manual tuning channel selection operation, detects the SD signal, and receives a broadcast station, it determines the presence or absence of the SD signal supplied via the SD detection circuit, and the SD signal Further determine whether is continuous,
If not continuous, the IF frequency data from the tuner circuit is counted for a predetermined time by the IF count circuit,
If on the basis of the count value of this channel selection state is determined not normal, further counts the IF frequency data from the tuner circuit year on IF counting circuit,
If it is determined that the channel selection state is not normal even after a predetermined number of counts,
The count in the IF count circuit is finished.
[0009]
According to a preferred embodiment of the receiver of the present invention, the control circuit includes a ROM (Read Only Memory) for storing a control program and an I / O circuit for interfacing with the outside. The I / O circuit, a display device for displaying keys and tuning state (TUNED) is connected.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration and operation of a preferred embodiment of a receiver according to the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 is a block diagram showing the configuration of a preferred embodiment of a receiver according to the present invention. This receiver includes a microcomputer 1 serving as a control unit, a key (KEY) 2, a display 3, a PLL (phase lock loop) circuit 4, a tuner circuit 5, an antenna 6, and an SD detection circuit 7. Here, the microcomputer 1 includes a ROM (read only memory) 11 and an I / O (input / output interface) circuit 12 together with a processor (not shown). The PLL circuit 4 includes an IF count circuit 41.
[0012]
Instruction information from the key 2 is input to the microcomputer 1, and the channel selection state by the tuner circuit 5 is displayed on the display 3 via the microcomputer 1. The microcomputer 1 has a configuration well known to those skilled in the art, and stores a program for instructing predetermined operation processing in the ROM 11. The I / O circuit 12 exchanges signals between the microcomputer 1, the key 2, and the display 3. The PLL circuit 4 receives a data signal (capture frequency), a clock signal, a latch signal, and the like from the microcomputer 1, performs a predetermined PLL operation, and sends a tuning signal (voltage) Vt and the like to the tuner circuit 5.
[0013]
On the other hand, an IF (intermediate frequency) signal is supplied from the tuner circuit 5 to the PLL circuit 4, and an SD signal is supplied to the microcomputer 1 via the SD detection circuit 7. Upon receiving this SD signal, the microcomputer 1 sends IF count start data to the IF count circuit 41 of the PLL circuit 4. When the counting operation for the IF frequency data is completed from the IF count circuit 41 provided in the PLL circuit 4, the microcomputer 1 receives the count value signal. The count signal and count end signal from the IF count circuit 41 are supplied to the I / O circuit 12 of the microcomputer 1, and a clock is sent to the PLL circuit 4 via the I / O circuit 12. The PLL circuit 4 sends IF frequency data to the microcomputer 1.
[0014]
In the configuration described above, the tuner circuit 5 determines the presence or absence of an SD signal by the SD detection circuit 7 after a certain scan time has elapsed. In the case of “present”, the SD signal is sent to the microcomputer 1 and the IF frequency signal is sent to the IF count circuit 41 of the PLL circuit 4 to start the count operation of the IF count circuit 41. This counting operation is performed for a predetermined time, and the microcomputer 1 receives the count value from the IF count circuit 41 and determines whether or not it is in a normal channel selection state. If the count data from the IF count circuit 41 has a specified frequency, it is considered that the broadcast station has been received, and the channel selection display (TUNED) element is turned on.
[0015]
Next, the “auto-tuning” operation of the receiver shown in FIG. 1 will be described with reference to the flowchart of FIG. The tuner circuit 5 sends the frequency data to the IF count circuit 41 of the PLL circuit 4 (step S11). Next, the presence / absence of an SD signal is determined when a certain time (for example, 125 mS) has elapsed (step S12). If the SD signal is “present”, IF count start data is sent to the PLL circuit 4 (step S13). The IF count value data counted by the IF count circuit 41 within a predetermined IF count time is sent to the microcomputer 1. The microcomputer 1 determines whether or not channel selection has been performed normally based on the received IF count value (step S14). When it is determined that the channel is normally selected (OK), the auto-tuning operation is terminated, and the display unit 3 is displayed that the tuning state (TUNED) is set (step S15).
[0016]
On the other hand, if it is determined in step S12 that the SD signal is “none”, the frequency for the next scan operation is UP / DOWN (increase / decrease) (step S17). Thereafter, the process returns to step S11 described above. If it is determined in step S14 that the normal channel selection is complete (NG), it is determined whether or not this determination is the second determination (step S16). If it is determined that it is the second time (step S16: Y), the process proceeds to step S17 described above, and the next scan operation is performed. On the other hand, when it is determined in step S16 that the determination is not the second time but the first time (step S16: N), the process returns to the above-described step S13, and the IF count operation is performed again.
[0017]
Next, the “manual tuning” operation of the receiver shown in FIG. 1 will be described with reference to the flowchart of FIG. The tuner circuit 5 sends frequency data to the IF count circuit 41 of the PLL circuit 4 (step S21). Thereafter, it is determined whether or not the UP / DOWN key 2 for increasing / decreasing the capture frequency for manual tuning is kept pressed (step S22). If the button is kept pressed, the process returns to step S21. If it is determined that the button has not been pressed, the process proceeds to the next processing step S23. When the button is kept pressed in step S22, the presence / absence of an SD signal is determined by parallel processing (step S27). If the SD signal is “present”, the tuning display (TUNED) is turned on on the display 3 (step S28). If the SD signal is “none”, the tuning display 3 is turned off and the process proceeds to step S22 described above (step 27).
[0018]
On the other hand, if the SD signal is generated for several milliseconds when the UP / DOWN key 2 is not kept pressed in step S22 described above, IF count start data is sent to the IF count circuit 41 of the PLL circuit 4 (step S22). S23). After the IF count operation is started, the microcomputer 1 receives the counted IF count value, and determines whether or not it is in a normal channel selection state based on the IF count value (step S24). If it is determined in step S24 that the channel is in a normal channel selection state (step S24: OK), the tuning display is made on the display 3 (TUNED), and the manual tuning operation is terminated (step S25). If it is determined that the channel selection state is not normal (step S24: NG), the manual tuning operation is terminated without performing tuning display on the display 3 (step S26).
[0019]
Auto and manual tuning operations are performed by the above processing. In consideration of the case where the SD signal changes due to radio interference after the channel selection operation ends, monitoring must be continued at regular time intervals. This “SD signal monitoring” operation will be described with reference to the flowchart of FIG. The SD signal data of the tuner circuit 5 is input from the I / O circuit 12 of the microcomputer 1 every several tens of milliseconds, for example (step S31). Then, the presence / absence of an SD signal is determined (step S32). If the SD signal is “present”, it is determined whether “present” is continuous (step S33). When the SD signal determination is “present” and this “present” is not continuous (first time) (step S33: N), the count start data is sent to the IF count circuit 41 of the PLL circuit 4 (step S34). After the IF count operation (for example, 80 mS), the microcomputer 1 receives the counted IF count value, and determines whether or not it is in a normal channel selection state based on this count value (step S35). If it is determined in this step S35 that the channel is in a normal channel selection state (step S35: OK), the display 3 is tuned and displayed (TUNED) (step S36), and the SD signal monitoring is terminated. If it is determined in step S35 that the channel selection operation is not normal (step S35: NG), the display 3 is not tuned and displayed (step S37), the SD signal monitoring is terminated, and the process proceeds to step S31. To do. Then, after several tens of milliseconds, the process returns to step S32.
[0020]
Next, when the SD signal is “present” (step S32: present) and continuous (step S33: Y), it is determined whether or not there is further interrupt processing (step S41). If there is no interrupt process (step S41: N), the process proceeds to the process of step S31 as it is, and the display 3 continues to maintain the tuning display (TUNED). At this time, if there is an interrupt process (step S41: Y), the interrupt process is terminated (step S42), and then the process returns to step S31.
[0021]
If the SD signal is “none” (step S32: none), as described above, the display 3 does not perform the tuning display (step S37), and proceeds to step S31. However, the interrupt process is performed when a key such as auto / manual tuning switching, preset calling, band switching or the like is pressed. However, if the SD signal of the tuner circuit 5 causes chattering due to the state of radio waves and data that repeats the presence / absence is input to the I / O circuit 12 of the microcomputer 1, the above-described IF count operation state is continued. Since the output mute continues during the IF count operation, the output mute continues and no output is produced.
[0022]
If the repetition time is long, the output mute is turned on / off, and the output may or may not be output. When the SD signal becomes “none” due to chattering, step S31 (SD signal input) → step S32 (SD signal “present”) → step S33 (not continuous) → step S34 (IF count start) → step S35 (IF data determination) NG) → step S37 (no tuning display) → step S31 (SD signal input). The operation for cutting off this cycle will be described with reference to the flowchart of FIG.
[0023]
If the IF count data is read in step S35 and the determination is NG, the process proceeds to step S38, and the number of NG is counted. If the number of NG is less than 6, the IF count data is continuously read at a constant time interval. If the number of NGs exceeds 6, the process proceeds to step S39 to determine the SD signal. Since it is already determined in step S35 that the channel is not in a normal channel selection state, the tuning display on the display 3 is not performed (step S37), and the SD signal monitoring is terminated.
[0024]
When such an operation is performed, it may be executed after the processing procedure of the auto tuning operation shown in FIG. 2 and after the processing procedure of the manual tuning operation shown in FIG . Immediate Chi, if not the IF count time SD signal and the SD signal when there is no interrupt processing in the "Yes" is set to "no". On the other hand, the IF count is performed when the SD signal is “present” for the first time and when the SD signal is “present” and the IF count data determination NG is counted. In the last processing procedure, since the previous processing data is held, it does not operate until the execution is completed. However, since it is more likely that chattering of the SD signal occurs continuously, it does not operate after a considerable amount of time, but is executed within a short time and the processing ends.
[0025]
The configuration and operation of the preferred embodiment of the receiver according to the present invention have been described in detail above. However, such an embodiment is merely an example of the present invention and does not limit the present invention. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.
[0026]
【The invention's effect】
As can be understood from the above description, according to the receiver of the present invention, the following remarkable practical effects can be obtained. That is, after selecting the desired broadcast station, the radio wave becomes weak, the IF count operation continues due to the chattering of the SD signal, the output mute is not released (the silence state continues), and it is misunderstood as a failure. It is possible to release the output mute after a period of time so that the broadcast can be received. Since it is possible to use a system IC in which the SD signal does not have hysteresis characteristics in the tuner circuit of the receiver, there is no restriction on circuit design, and circuit design is facilitated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a preferred embodiment of a receiver according to the present invention.
FIG. 2 is a flowchart showing an auto-tuning operation of the receiver shown in FIG.
FIG. 3 is a flowchart showing a manual tuning operation of the receiver shown in FIG. 1;
4 is a flowchart showing an SD signal monitoring operation of the receiver shown in FIG.
5 is a flowchart showing an SD signal monitoring operation for cutting off the influence of chattering in the receiver shown in FIG. 1;
[Explanation of symbols]
1 Microcomputer 11 ROM
12 I / O circuit 2 Key 3 Display 4 PLL circuit 41 IF count circuit 5 Tuner circuit 6 Antenna

Claims (3)

A tuner circuit that selects a signal received from the antenna, possess a PLL (phase locked loop) circuit for supplying a tuning signal to said tuner circuit, detecting an SD signal generated during reception of the desired broadcast station from the tuner circuit A channel selection state based on the SD signal received from the tuner circuit, the IF count circuit receiving the IF signal from the tuner circuit and counting IF frequency data, the SD signal from the SD detection circuit and the count value from the IF count circuit And a control circuit that controls the channel selection operation, and in a receiver that performs auto or manual tuning channel selection operation,
The tuner circuit performs the automatic or manual tuning tuning operation, said when receiving the detected broadcasting station SD signal, said determining whether the SD signal supplied via the SD detecting circuit SD It is further determined whether or not the signal is continuous. If the signal is not continuous, the IF frequency data from the tuner circuit is counted for a predetermined time by the IF count circuit,
If on the basis of the count value of this channel selection state is determined not normal, further counts the IF frequency data from the tuner circuit by the IF count circuit,
A receiver characterized in that if it is determined that the channel selection state is not normal even after a predetermined number of counts, the counting in the IF count circuit is terminated . The receiver according to claim 1 , wherein the control circuit is a microcomputer including a ROM (Read Only Memory) for storing a control program and an I / O circuit for interfacing with the outside. The receiver according to claim 2 , wherein the I / O circuit is connected to a display for displaying a key and a tuning state (TUNED).

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