JPH0744476B2 - Radio receiver time correction method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time correction method for a radio receiver, and more particularly to a method for correcting the current time based on time data sent superposed on a broadcast signal. .

<Prior Art> In a car radio, in addition to being able to easily obtain traffic information, it is required to have an advanced tuning function. Especially in Europe, where FM broadcasting, which has a relatively small service area, is the main body of radio broadcasting services and the ratio of car radio reception is high, this requirement is strong. Therefore, in order to meet this demand, RDS (Radio Data System) has been proposed and put into practical use by the European Broadcasting Union. This RDS is FM
Various digital data (RDS data) for radio broadcast signals
This is a method of superimposing, and the message includes the program identification data (PI) of the currently received FM broadcast, the broadcasting station frequency list (AF) that is broadcasting the same program, etc. A tuning operation can be performed. For example, demodulate the frequency data (AF list) of the same program broadcasting station, check the received electric field strength by sequentially tuning to each AF station on the AF list, and check the received electric field strength of the current receiving station. In the following cases, the reception field strength is tuned to the frequency of the AF station with the maximum intensity (called automatic tracking), and good reception is always possible.

By the way, RDS data includes clock time, which is time information in minutes, in addition to tuning information such as PI code and AF list. This clock time is not always sent (it is sent at 1-minute intervals only in the case of a predetermined group of 16 types of RDS data information groups), but if it is sent, it will be received each time. The current time of the timer is corrected, and it can always be displayed in accordance with the correct time.

<Problems to be Solved by the Invention> However, although it is preferable that the clock time is accurate, the accurate clock time may not be sent due to equipment conditions on the broadcasting station side or a failure of the clock on the broadcasting station side. . In particular, the clock time is disturbed in Sweden at the moment, and the time display is random.

For this reason, a timer correction on / off switch is provided, and when the switch is off, the time is not corrected even if the clock time is received, and the time is corrected based on the clock time only when the switch is on. I have to.

However, in such a method, the area where the switch may be turned on / off is not known, and in many cases, the switch remains turned off. Moreover, the switch operation becomes troublesome, and an extra switch is required, so that the operation or It was inconvenient for the cost.

The object of the present invention is to determine whether or not to correct automatically based on the clock time without providing a switch,
Moreover, it is an object of the present invention to provide a time correction method in an RDS receiver that can always display an accurate time when making a correction and can display the time of a timer of the RDS receiver when making no correction.

<Means for Solving the Problem> According to the present invention, the above-mentioned problem is solved by: means for monitoring the elapsed time after time correction; means for monitoring whether time data is superposed on a broadcast signal and superposed; If
A means for determining the allowable error time based on the elapsed time, a means for determining whether the difference between the current time indicated by the timer and the time indicated by the time data is smaller than the allowable error time, and when it is smaller, the current time of the timer is sent. This is achieved by the correction means that corrects the time data that has been received and does not correct it if it is not small.

<Operation> While monitoring the elapsed time after the time correction, it is also monitored whether the time data is superposed on the broadcast signal and sent, and if superposed, the allowable error time is determined based on the elapsed time, It is judged whether the difference between the current time indicated by the timer and the time indicated by the time data is smaller than the allowable error time. If it is smaller, the current time of the timer is corrected by the sent time data. Do not correct.

<Embodiment> FIG. 1 is a block diagram of an essential part of an RDS radio receiver for realizing a time correction method according to the present invention.

1 is an antenna, 2 is a front end, and PL described later
An intermediate frequency signal is generated by tuning to a predetermined broadcasting station based on the voltage signal output from the L circuit. An intermediate frequency amplifier 3 amplifies the intermediate frequency signal converted by the front end 2. A stereo demodulation circuit (MPX) 4 demodulates the intermediate frequency signal input from the intermediate frequency amplifier 3 into a stereo signal. Reference numeral 5 is a mute circuit, 6 is an amplifier (AMP), and 7 is a speaker, which is driven by the amplifier 6 and outputs sound.

Reference numeral 8 is a 57 KHz band pass filter (BPF) that passes a 57 KHz subcarrier whose amplitude is modulated based on RDS data. An RDS decoder 9 demodulates AF code, PI code, clock time, etc. from the output of the bandpass filter. An error correction circuit 10 is an R code such as an AF code, a PI code and a clock time demodulated by the RDS decoder 9.
The error of the DS data is detected while synchronizing with each group, and the error is corrected.

A signal meter 11 detects and outputs the strength (level) La of the intermediate frequency signal output from the intermediate frequency amplifier 3, that is, the received electric field strength. 12 is a station detector, which is the frequency deviation Δf (bandwidth) of the received signal
When the signal level is within the range and the signal level is equal to or higher than a predetermined level, it is determined that the receiving station exists.

13 is a controller of a microcomputer configuration that performs automatic tracking processing, and tuning data such as AF list included in RDS data,
Performs digital tracking processing along with automatic tracking processing based on signal strength La, station detector output signal SD, etc.

A time correction control unit 14 controls the time correction of the built-in timer based on the clock time Trds sent by being superimposed on the AF broadcast station signal.

15 is a time display / time display section 15a and a time adjustment section 15b.
The adjusting unit 16 is a PLL circuit that inputs a voltage signal corresponding to the reception frequency data FDT input from the controller 13 to the front end 2 and tunes it to a predetermined broadcasting station.

FIG. 2 is a block diagram of the time correction control unit 14, where 14a is R
A clock time identification / extraction unit that determines whether or not the DS data includes the clock time Trds and extracts the time data Trds, and 14b is a timer unit,
It has a first timer TM1 for measuring the current time Ta and a second timer TM2 for measuring the corrected elapsed time Tc.

14c is a permissible error time calculation unit. When the RDS data includes the clock time Trds, the elapsed time Tc input from the timer unit is multiplied by a predetermined error rate ε to determine the permissible error time. Emax is calculated and output. Note that the error rate ε is, for example, the time error rate of the quartz timepiece, and the allowable error time Emax is determined by rounding up the fractional seconds.

Reference numeral 14d is a comparison calculation unit that compares the current time Ta indicated by the timer TR1.
It is determined whether the difference between the clock times Trds included in the RDS data is smaller than the allowable error time Emax, that is, | Ta−Trds | ≦ Emax (1) holds.

14e is a time correction unit, and the current time and clock time Trds
If the difference is smaller than the allowable error time Emax (when the formula (1) is satisfied), the timer TM1 is used at the clock time Trds.
The current time is corrected (Trds → Ta), and the elapsed time is counted by the timer TM2 from the time, and when the expression (1) is not satisfied, the clock time Trds is not corrected. Further, the time correction unit 14e corrects the current time based on the time correction data input from the time adjustment unit 15b (see FIG. 1), and causes the timer TM2 to measure the elapsed time from the time.

The time correction process of the present invention will be described below with reference to FIGS. 1 and 2. The timer TM1 indicates the current time Ta,
It is assumed that the timer TM2 indicates the elapsed time Tc after correction.

While receiving the broadcast program from the predetermined broadcasting station, the clock time identification / extraction unit 14a checks whether the RDS data includes the clock time Trds, and if it does, the high-level signal ST And the clock time Trds is extracted and input to the comparison operation unit 14d and the time adjustment unit 14e in the subsequent stage.

When the high-level signal ST is input, the allowable error time calculating unit 14c multiplies the elapsed time Tc after time correction input from the timer unit 14b by a predetermined error rate ε to obtain the allowable error time Emax. It is calculated and output to the comparison calculation unit 14d.

The comparison calculation unit 14d calculates the absolute error | Ta−Trds | of the current time Ta and the clock time Trds indicated by the timer TM1, compares the absolute error and the maximum error Emax, and when the absolute error is smaller, Outputs the correction enable signal TCE (when the expression (1) is satisfied).

When the correction enable signal TCE is input, the time correction unit 14e corrects the current time of the timer TM1 at the clock time Trds and also causes the timer TM2 to measure the elapsed time Tc thereafter.

When the clock time is superimposed and sent, the time correction process is performed at 1-minute intervals, and the allowable error time Emax becomes 1 second. If the clock time is within 1 second, the clock time Is corrected and the correction is performed, the minute unit of the current time Ta is set as the instructed clock time, and the second unit or less of the current time Ta is corrected to 0.

When the correction enable signal TCE is not input (when the expression (1) is not satisfied), the time correction unit 14e does not correct the current time with the clock time Trds.

The above is the case where the clock time is superimposed on the FM broadcast, but the current time can be corrected using a correction knob or the like. That is, the time correction unit 14e is the time adjustment unit 15b.
When the time correction data is input from (see FIG. 1), the current time Ta of the timer TR1 is corrected based on the time correction data, and thereafter the elapsed time Tc is counted by the timer TR2.

Note that the clock time Trds is not superimposed on the FM broadcast RD
At the time when the vehicle enters the overlapping area from the S area, the normal elapsed time Tc is large and the allowable error range is large.

<Effects of the Invention> As described above, according to the present invention, the elapsed time after time correction is monitored, and whether or not time data is superposed on a broadcast signal and sent is monitored. The allowable error time is determined based on, and it is determined whether the difference between the current time indicated by the timer and the time indicated by the time data is smaller than the allowable error time. If it is smaller, the current time of the timer is sent. Since it is configured so that it is not corrected when it is not small, it can automatically determine whether to correct it based on the clock time without providing a switch, and when correcting it, always display the accurate time. If not corrected, the time of a timer having a radio receiver can be displayed.

[Brief description of drawings]

FIG. 1 is a block diagram of an RDS radio receiver according to the present invention, and FIG. 2 is a block diagram of a time correction control unit. 14 …… Time correction control unit 14a …… Clock time identification / extraction unit 14b …… Timer unit 14c …… Allowable error time calculation unit 14d …… Comparison calculation unit 14e …… Time correction unit 15 …… Time display / adjustment unit

Claims (1)

[Claims] 1. A time correction method for a radio receiver for correcting the current time of a timer based on time data sent by being superimposed on a broadcast signal, and monitoring the elapsed time after the time correction and at the same time the broadcast signal. It is monitored whether the time data is superposed and sent, and if superposed, the allowable error time is set based on the elapsed time, and the difference between the current time indicated by the timer and the time indicated by the time data is set. Is smaller than the allowable error time, and if it is smaller, the current time of the timer is corrected by the sent time data, and if it is not smaller, it is not corrected.