JPH0645877A - Automatic tuning receiver - Google Patents

Abstract

PURPOSE:To provide an automatic tuning receiver free from the trouble of tuning operation by controlling continuation/stop of scanning by a threshold for stop stored in a ROM at the time of the occurrence of abnormality in an E<2>PROM where a threshold for frequency scanning stop is stored. CONSTITUTION:The threshold for backup, for example, data for check as 8-bit data is preliminarily written in a ROM 172. When it is regarded that error occurs in an E<2>PROM 173, the threshold for backup is used to stop the tuning scanning. The tuning control routine executed by a CPU 171 reads out data for check from the ROM 172 and the E<2>PROM 173 and discriminates whether they coincide with each other or not. If they do not coincide with each other, the threshold for backup stored in the ROM 172 is used and is compared with a field intensity signal. The scanning frequency is incremented when the field intensity signal is smaller, and scanning is stopped or terminated when it is larger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tuning receiver equipped with an electronic tuning tuner, and more particularly to an automatic tuning receiver having a backup reception sensitivity setting value.

[0002]

2. Description of the Related Art Most of recent broadcast wave receivers are equipped with an electronic tuning tuner using a so-called phase locked loop (hereinafter referred to as PLL). In the receiver of this type, the scanning is stopped automatically when the reception frequency band is automatically scanned and the reception wave which gives the reception sensitivity equal to or higher than a predetermined threshold value is received.

Generally, as the reception sensitivity, a so-called signal meter voltage value output from the detection circuit is used, and this voltage value is compared with a threshold value obtained by dividing the reference voltage with a variable resistor. is there. However, adjustment of this variable resistor not only requires work time, but also cannot avoid variations among products.

In order to solve this problem, the present applicant has
By inputting a radio wave with a predetermined electric field strength to the receiver in the adjustment process and storing the signal meter voltage value for this as a threshold value, automatic tuning that can eliminate variations between products and shorten the working time A receiver has already been proposed (JP-A-3-182113).

[0005]

However, a so-called E ² PROM is applied as a memory for storing the threshold value, and the error occurrence probability of this type of memory is such that data is erased like a fuse burn-out type ROM. , Higher than ROM that cannot be rewritten. Therefore, once an error occurs in the set threshold value, the scanning does not stop even if the synchronous scanning is performed, or the scanning frequently stops.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an automatic tuning receiver in which no trouble occurs in the tuning operation even when it is considered that an error has occurred in the E ² PROM. To aim.

[0007]

SUMMARY OF THE INVENTION An automatic tuning receiver according to the present invention automatically scans a reception frequency, and when a broadcast wave having a predetermined electric field strength is received, the scanning is stopped to enter a receiving state. A receiver, which is an electric field strength detecting means for outputting a voltage proportional to the electric field strength of a received broadcast wave, and an electric field strength detection as a threshold value for tuning scanning stop when an adjusting broadcast wave having a known electric field strength is received The voltage detected by the means is stored in the first storage means for storing a predetermined bit pattern as the first inspection data, the predetermined backup threshold value, and the first storage means. Second storage means for storing data having the same bit pattern as the inspection data and second inspection data; and a bit pattern of the inspection data stored in the first storage means during broadcast wave scanning If the bit patterns of the inspection data stored in the second storage means are compared and coincident with each other, the synchronous scanning stop threshold value stored in the first storage means is used to stop the synchronous scanning, and if they do not coincide with each other. Control means for stopping the tuning scan using the backup threshold stored in the second storage means.

[0008]

In the automatic tuning receiver according to the present invention, a standard backup threshold value is set in advance in the ROM in which data cannot be erased and rewritten, and E ² PRO is set.
This backup threshold is used to stop the tuning scan if M is considered to have failed.

[0009]

1 is a block diagram of an embodiment of an automatic tuning receiver according to the present invention, which is a receiver using a tuning method by a PLL. That is, the broadcast wave received by the antenna 11 is sent to the front end 12, and the received wave desired to be received is selected and converted into an intermediate frequency of a predetermined frequency.

The intermediate frequency is amplified by the intermediate frequency amplifier 13 and then converted into an audible signal by the detector 14. The detector 14 outputs an audible signal and an electric field strength signal proportional to the electric field strength of the received broadcast wave. The audible signal is amplified by the low frequency amplifier 15 and output from the speaker 16 as an acoustic signal.

This receiver is controlled by a control unit 17 composed of a microcomputer. That is, the control unit 17
Centering on the bus 170, CPU 171, ROM 17
2, E ² PROM 173, Man-machine interface 174, A / D converter 175, frequency divider 176,
Reference frequency transmission unit 177, phase comparison unit 178 and D /
It is composed of an A converter 179.

The front end 12, the frequency dividing unit 176, the reference frequency transmitting unit 177, the phase comparing unit 178 and the D / A converter 179 constitute a PLL and selects a tuning frequency. The Man-Machine interface 174 includes a display for displaying the reception frequency f _R and a setting button.

Further, in the ROM 172, the backup threshold value VB and the inspection data CHECK which is, for example, 8-bit data are written in advance. Figure 2 is CP
A threshold setting routine executed in U171,
It is executed in the adjustment process at the manufacturer. A radio wave whose electric field strength is known in advance is input to the antenna 11, and the electric field strength signal VT output from the detection unit 14 is read in step 201.

In step 202, the inspection data CHECK written in the ROM 172 is read. Man-machine interface 174 at step 203
Press the setting button included in. And step 2
04 E ² PROM173 write field strength signal VT to write the test data CHECK to E ² PROM173 at step 205.

FIG. 3 is a flowchart of the tuning control routine executed by the CPU 171, which is executed when the setting button included in the Man-Machine interface 174 is pressed to change the reception frequency. In step 301, the scanning frequency f is initialized. In step 302, the inspection data CH is read from the ROM 172.
ECK is read, and in step 303 E ² PRO
The inspection data CHECK 'is read from M173.

If the E ² PROM 173 is normal, CHE
Since CK and CHECK 'should match, CH
It is possible to determine whether the E ² PROM 173 is normal by determining whether ECK and CHECK 'match. In step 304, it is determined whether CHECK and CHECK 'match, and if an affirmative determination is made, the process proceeds to step 305.

In step 305, the scanning stop threshold value VS is set.
To the electric field strength signal V stored in the E ² PROM 173.
As T, the process proceeds to step 307. If a negative determination is made in step 304, the process proceeds to step 306, the scanning stop threshold value VS is set to the backup threshold value VB stored in the ROM 172, and the process proceeds to step 307.

In step 307, the electric field intensity signal V is read, and in step 308, it is determined whether or not it is larger than the scanning stop threshold value VS. If a negative determination is made in step 308, the process proceeds to step 309 and the scanning frequency f is incremented by Δf to continue scanning, and then step 302 is performed.
Return to. If a positive determination is made in step 308, step 3
Proceeding to step 10, the scanning is stopped, and the execution of this routine ends.

[0019]

In the automatic tuning receiver according to the present invention, the E ² P storing the threshold value for stopping the frequency scanning is stored.
Even when an abnormality occurs in the ROM, the continuous stop of scanning is controlled by the backup threshold value stored in the ROM, and it is prevented that the scanning does not stop or the frequent stop is repeated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an automatic tuning receiver according to the present invention.

FIG. 2 is a flowchart of a threshold value setting routine.

FIG. 3 is a flowchart of a tuning control routine.

[Explanation of symbols]

 11 ... Antenna 12 ... Front end 13 ... Intermediate frequency amplification part 14 ... Detection part 15 ... Low frequency amplification part 16 ... Speaker 17 ... Control part

Claims (1)

[Claims] 1. Automatically scanning a reception frequency, and when a broadcast wave having a predetermined electric field strength is received, the scanning is stopped,
In the automatic tuning receiver that is in the receiving state, the electric field strength detection means that outputs a voltage proportional to the electric field strength of the received broadcast wave, and the tuning scan stop threshold when the adjustment broadcast wave whose electric field strength is known are received. First storage means for storing the voltage detected by the electric field strength detection means as a value, and a predetermined bit pattern as the first inspection data; a predetermined backup threshold value and the first backup threshold value; A second storage unit for storing the second inspection data having the same bit pattern as the inspection data stored in the first storage unit; and a second storage unit stored in the first storage unit during broadcast wave scanning. The bit pattern of the first inspection data and the bit pattern of the second inspection data stored in the second storage means are compared, and if they match, the tuning scan stored in the first storage means For stop Control means for stopping the tuning scan using the threshold value, and stopping the tuning scan using the backup threshold value stored in the second storage means in case of disagreement;
An autotuned receiver characterized by having.