JP2002368585A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver solving a problem that presence/absence of an SD signal is affected by making a radio wave strength weak or strong after the receiver is turned to a desired broadcasting station. SOLUTION: The receiver is provided with a tuner circuit 5 for being inputted of a signal received by an antenna 6, a PLL circuit 4, which is provided with an IF count circuit 41 for receiving an IF signal from this tuner circuit 5, for supplying a synchronizing signal to the tuner circuit 5 and a microcomputer 1 as a control circuit for being inputted of the SD signal from the tuner circuit 5 and sending a control signal to the PLL circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver, and more particularly, to a receiver such as a radio having an auto-tuning function and a manual tuning function for searching for a broadcast wave and tuning to a desired broadcasting station.

[0002]

2. Description of the Related Art There is provided a channel selecting device for receiving a broadcast wave from a desired broadcasting station by a receiver. This tuning device,
It has an LC tank (resonance) circuit composed of an inductor (L) and a capacitor (C). By varying the capacitor (or inductor), the resonance frequency is varied to tune to the frequency of the desired broadcasting station and select a station. . When selecting a channel 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 or decreasing the capture frequency. The resonance frequency of the tuning device is continuously changed (scanned) by automatic or manual tuning.
Then, after confirming that the tuning display (TUNED) element is lit by the SD signal generated based on the M conversion processing at the time of receiving the desired broadcast station, the frequency scanning (change) is stopped. At this time, the presence / absence of the SD signal is checked, and if “Yes”, the IF count is performed. After confirming the IF frequency, the output mute (silence state) is released and the broadcast is received.

[0003] When the radio wave of the desired broadcast station is weakened due to radio interference or interruption of the broadcast while the desired broadcast station is selected, the SD signal becomes "absent", and then the radio wave becomes stronger and the SD signal becomes "present". There can be. In this case, the IF count is performed, and after confirming the IF frequency, the output mute is released and the broadcast is received.

[0004]

After the receiver selects a desired broadcast station, the radio wave becomes weak and the selected station is displayed (TUNED).
When the lighting level of the element is near the threshold, the IF count is performed when the SD signal changes from “absent” to “present”. Then, after confirming the IF frequency, the tuning display (TUNED) element is turned on. At the same time, the output mute is applied to prevent noise to the output during IF counting, and the output mute is released after the tuning display (TUNED) element is turned on. Also, this SD signal is "Yes"
If the operation is repeated continuously from “No” to “No” and “Yes”, the output mute is applied to prevent the above-mentioned noise, and the output is not output or the output is intermittent. Was not easily released.

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 this integration circuit is increased, the frequency scan time is approached during the auto-tuning operation, so that the tuning operation cannot be performed and the acquisition frequency is skipped.

In the microcomputer program, after the tuning operation,
Even if the SD signal changes from “No” to “Yes” due to the strength of the radio wave, the IF count is not performed, and the SD signal continuously changes from “Yes” to “No” and “No” to “Yes”. Also, the tuning display (TUNED) element is made to follow from turning on to turning off and from turning off to turning on. Also, when the broadcasting station stops transmitting radio waves and turns on the power of the receiver before re-broadcasting, the tuning operation is performed once and the tuning display (TUN) is performed.
After the ED) element is turned off, the tuning display (TUNED) element remains off even if the radio wave becomes stronger.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a receiver for preventing the output mute from being canceled by the chattering of the SD signal and being erroneously recognized as a failure.

[0008]

A receiver according to the present invention has a tuner circuit for selecting a signal received from an antenna, and a PLL (phase locked loop) circuit for supplying a tuning signal to the tuner circuit. An IF count circuit that counts IF frequency data from a tuner circuit in a predetermined tuning state; and a control circuit that determines a tuning state based on the count value from the IF count circuit and controls a tuning operation. And

Further, according to a preferred embodiment of the receiver of the present invention, the predetermined tuning state is a state where the tuner circuit is generating the SD signal. After transmitting the frequency data to the PLL circuit, the frequency scanning operation and the state of the tuner circuit generating the SD signal are processed in parallel. While the tuner circuit continues to monitor according to the state in which the SD signal is being generated, the initial value, the continuous value, and the release value of the SD signal are determined, and the release value is counted for a certain period of time. A monitor circuit that determines a channel selection state based on a count value obtained by counting IF frequency data from
The SD signal repeats the chattering state to stop continuing the IF count operation. The control circuit includes a ROM (read only memory) for storing a control program and an I / O circuit for interfacing with the outside. I / O
The circuit is connected with a key and a display for displaying a tuning state (TUNED).

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and operation of a preferred embodiment of a receiver according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a preferred embodiment of a receiver according to the present invention. The receiver includes a microcomputer 1 serving as a control unit, a key (KEY) 2, a display 3, a PLL (phase locked 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 together with a processor (not shown).
(Input / output interface) The circuit 12 is included. Further, the PLL circuit 4 includes an IF count circuit 41.

Instruction information from the key 2 is input to the microcomputer 1, and the tuning state of the tuner circuit 5 is determined by the microcomputer 1.
Is displayed on the display unit 3 via. The microcomputer 1 has a configuration known to those skilled in the art, and stores a program for instructing a predetermined operation process in the ROM 11. The I / O circuit 12 sends and receives signals between the microcomputer 1 and the keys 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 to the tuner circuit 5.

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. Microcomputer 1
Upon receiving this SD signal, sends the IF count start data to the IF count circuit 41 of the PLL circuit 4. P
The IF count circuit 41 provided in the LL circuit 4
When the count operation for the frequency data is completed, the microcomputer 1 receives the count value signal. The count signal and the count end signal from the IF count circuit 41 are supplied to the I / O circuit 12 of the microcomputer 1,
The clock is sent to the PLL circuit 4 via the / O circuit 12. The PLL circuit 4 sends the IF frequency data to the microcomputer 1.

In the configuration described above, after the tuner circuit 5 has passed a predetermined scan time, the SD detection circuit 7
The presence or absence of the D signal is determined. If “Yes”, the SD signal is sent to the microcomputer 1 and the IF frequency signal is
The signal is sent to the IF count circuit 41 of the L circuit 4 and the count operation of the IF count circuit 41 is started. 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 the channel is in a normal tuning state. If the count data from the IF count circuit 41 is a prescribed frequency, it is regarded that a broadcast station has been received, and a tuning display (TUNED) element is lit and displayed.

Next, referring to the flowchart of FIG.
The "auto tuning" operation of the receiver shown in FIG. 1 will be described. The tuner circuit 5 sends out frequency data to the IF count circuit 41 of the PLL circuit 4 (step S1).
1). Next, when a certain time (for example, 125 mS) has elapsed,
It is determined whether or not there is an SD signal (step S12). If the SD signal is “present”, the control unit sends IF count start data to the PLL circuit 4 (step S13). 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 the channel selection has been normally performed based on the received IF count value (step S1).
4). When it is determined that the channel has been tuned normally (OK)
The auto-tuning operation is terminated and the tuning state (T
(UNED) is displayed on the display 3 (step S15).

On the other hand, if it is determined in step S12 that the SD signal is "absent", the frequency for the next scanning operation is UP / DOWN (increase / decrease) (step S17). Thereafter, step S1 described above is performed.
It returns to the process of 1. If it is determined in step S14 that the channel selection is normally completed (NG), it is determined whether or not this determination is the second determination (step S16). 2
If it is determined that the current time has been reached (step S16:
Y) The process proceeds to step S17 to perform the next scanning operation. On the other hand, in step S16, instead of the second time, 1
If it is determined that this is the second determination (step S1
6: N), the process returns to step S13, and the IF counting operation is performed again.

Next, referring to the flowchart of FIG.
The "manual tuning" operation of the receiver shown in FIG. 1 will be described. The tuner circuit 5 sends out frequency data to the IF count circuit 41 of the PLL circuit 4 (Step S2)
1). Thereafter, it is determined whether the UP / DOWN key 2 for increasing or decreasing the acquisition 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. In step S22, when the button is kept pressed, the presence or absence of an SD signal is determined by parallel processing (step S27).
When the SD signal is “present”, the tuning display (T
(UNED) is turned on (step S28). If the SD signal is "absent", the tuning display 3 is turned off and the process proceeds to the above-described step S22 (step 27).

On the other hand, in step S22 described above, UP /
If the DOWN key 2 is not pressed and the SD signal is generated for several milliseconds, the IF count start data is sent to the IF count circuit 41 of the PLL circuit 4 (step S23). After the start of the IF counting operation, the microcomputer 1 receives the counted IF count value and determines whether or not the channel is in a normal channel selection state based on the IF count value (step S24). If it is determined in this step S24 that the channel is in the normal tuning state (step S24: O
K), the tuning is displayed on the display 3 (TUNED), and the manual tuning operation ends (step S25).
If it is determined that the channel is not in a normal tuning state (step S24: NG), the manual tuning operation ends without performing tuning display on the display 3 (step S2).
6).

With the above processing, automatic and manual channel selection operations are performed. After the channel selection operation is completed, monitoring must be continued at regular time intervals in consideration of the case where the SD signal changes due to radio wave interference. This "SD signal monitor" operation will be described with reference to the flowchart of FIG. The SD signal data of the tuner circuit 5 is transferred to the I
Input from the / O circuit 12, for example, after several tens of milliseconds (step S31). Then, the presence or absence of the SD signal is determined (step S32). If the SD signal is "Yes",
It is determined whether “Yes” is continuous (step S33). SD
The signal judgment is “Yes” and this “Yes” is not continuous (first time)
At this time (step S33: N), 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 the channel is in a normal channel selection state based on the count value (step S35). This step S3
If it is determined in step 5 that the channel selection state is normal (step S35: OK), the display 3 is tuned (TUNED) (step S36), and the monitoring of the SD signal is terminated. If it is determined in step S35 that the operation is not a normal tuning operation (step S35: NG), tuning display is not performed on the display 3 (step S37), the monitoring of the SD signal ends, and the process proceeds to step S31. I do. And the number 10
After mS, the process returns to step S32.

Next, when the SD signal is "present" (step S3).
2: Yes), if continuous (step S33: Y), it is determined whether or not there is further interrupt processing (step S4).
1). If there is no interrupt processing (step S41:
N), the process directly proceeds to the process of step S31, and the display 3 keeps the tuning display (TUNED). At this time, if there is an interruption process (step S41: Y), the interruption process ends (step S42), and then the process returns to the step S31.

If the SD signal is "absent" (step S32: absent), as described above, the display 3 does not perform tuning display (step S37), and proceeds to step S31. However, the interrupt processing is performed when a key such as auto / manual tuning switching, preset calling, band switching, or the like is pressed. However, when the SD signal of the tuner circuit 5 causes chattering due to the state of the radio wave and data that repeats presence / absence is input to the I / O circuit 12 of the microcomputer 1, the above-described IF count operation state is continued. During the IF count operation, the output mute is continuous, so that the output mute continues and no output is output.

If the repetition time is long, the output mute is turned on / off, and the output is stopped or output. When the SD signal becomes "Nothing" due to chattering,
Step S31 (SD signal input) → Step S32 (S
D signal “Yes”) → Step S33 (not continuous) → Step S34 (IF count start) → Step S35 (I
F data determination NG) → Step S37 (no tuning display)
→ Step S31 (SD signal input) is performed. The operation for interrupting this cycle will be described with reference to the flowchart of FIG.

In step S35, the IF count data is read, and if the determination is NG, the flow shifts to step S38 to count the number of NG. If the number of NGs is less than 6, the IF count data is continuously read at regular time intervals. If the number of NGs exceeds six, the flow shifts to step S39 to determine the SD signal.
Then, since it is already determined in step S35 that the channel is not in a normal tuning state, the tuning display is not performed on the display 3 (step S37), and the monitoring of the SD signal is terminated.

In the case where such an operation is performed, FIG.
3 and after the manual tuning operation shown in FIG. 3. In the present invention, the latter operation is selected. That is, when the IF count is not performed, when the SD signal is “present” and there is no interrupt processing, and when the SD signal is “absent”. On the other hand, when performing IF counting, SD
When the signal is “present” for the first time and when the SD signal is “present” and I
This is when the F count data determination NG is counted. At the time of the last processing procedure, since the previous processing data is held, it does not operate until the execution is completed. However, since the chattering of the SD signal often occurs continuously, it does not operate after a considerable time has elapsed, but is executed in a short time and the processing ends.

The configuration and operation of the preferred embodiment of the receiver according to the present invention have been described above in detail. However, such an embodiment is merely an example of the present invention and does not limit the present invention in any way. It will be readily apparent to those skilled in the art that various modifications and changes can be made in accordance with the particular application without departing from the spirit of the invention.

[0026]

As will be understood from the above description, according to the receiver of the present invention, the following remarkable practical effects can be obtained. That is, when the desired radio station is selected, the radio wave becomes weak, the IF counting operation continues for chattering of the SD signal, and the output mute is not released (silent state continues). After a certain time, the output mute is released and the broadcast can be received. Since the SD signal can be used for the tuner circuit of the receiver even with the system IC without the hysteresis characteristic,
There are no restrictions on circuit design, and circuit design becomes easier.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the 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.

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]

 Reference Signs List 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 (6)

[Claims] 1. A tuner circuit for selecting a signal received from an antenna, and a PL for supplying a tuning signal to the tuner circuit.
An IF count circuit for counting IF frequency data from the tuner circuit in a predetermined channel selection state;
A receiver for determining a tuning state based on a count value from a count circuit and controlling a tuning operation. 2. The receiver according to claim 1, wherein the predetermined channel selection state is a state in which the tuner circuit is generating an SD signal. 3. The receiver according to claim 1, wherein after transmitting the frequency data to the PLL circuit, a frequency scan operation and a state of the tuner circuit generating the SD signal are processed in parallel. 4. While the tuner circuit continues to monitor according to the state in which the tuner circuit is generating the SD signal, the tuner circuit determines an initial value, a continuous value, and a release value of the SD signal, and determines a predetermined time. The release value is counted, and IF from the tuner circuit is counted.
A monitor circuit for judging a channel selection state based on a count value obtained by counting frequency data, wherein the SD signal repeats a chattering state to stop continuing the IF count operation. 1,
4. The receiver according to 2 or 3. 5. The control circuit 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 an external device. Receiver. 6. The receiver according to claim 5, wherein a key and a display for displaying a tuning state (TUNED) are connected to the I / O circuit.