JPH06296144A - Radio receiver - Google Patents

Abstract

PURPOSE:To shorten a tuning time by excluding an excess wait time while keeping the accuracy of sufficient tuning by providing a control means storing a tuning condition including the wait time, selecting and setting the tuning condition and checking the result to the radio receiver making electronic tuning. CONSTITUTION:Since a tuning condition storage means 6 storing a tuning condition including a wait time is provided, the wait time suitable for the destination of the imported radio receiver is stored, Then a tuning condition selection means 7 selects a wait time depending on the selection and setting and when a frequency multiple factor of a frequency multiplier means 2 is changed, after the wait time passes, the communication 5 checks a discrimination result outputted by a broadcast presence discrimination means 4. As a result, an essential wait time depending on the destination is selected, the tuning is made accurate and an excess wait time is excluded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiver (synthesizer receiver) for electronic tuning. The present invention is particularly applicable to, but is not limited to, a radio receiver that performs electronic tuning that can correspond to different radio regulations (inter-station frequency, reception frequency range, etc.).

[0002]

2. Description of the Related Art Electronic tuning in a radio receiver is generally realized by electronically varying the frequency of a signal mixed with a received signal in a mixer (first detector) used in a so-called superheterodyne system. Has been done. An oscillator (local oscillator) serving as a reference and a frequency multiplication circuit are used as means for electronically varying the frequency of the mixed signal, and the frequency multiplication circuit includes a PLL (Phase).
Circuit technology called Locked Loop is applied.

FIG. 4 is a block diagram of a conventional electronic tuner and its control system. The demodulation circuit 21 is configured by a heterodyne system, and as is well known, a high frequency amplification circuit 21a,
The mixing circuit 21b, the intermediate frequency amplifier circuit 21c, the detection circuit 21d, etc. are the main circuits. The reception signal is mixed with the output of the voltage controlled oscillator 22a by the mixing circuit 21b, and the reception frequency is converted to the intermediate frequency (tuning frequency).

The output of the voltage controlled oscillator 22a is the frequency divider 22
It is fed back to the input for controlling the oscillation frequency of the voltage controlled oscillator 22a via b, the phase comparator 22c, and the low-pass filter 22d to form a so-called PLL. In the phase comparator 22c, the reference frequency signal generated by the local oscillator 23 and the output signal of the voltage controlled oscillator 22a divided by the frequency divider 22b are phase-compared, and by the above feedback, the voltage controlled oscillator 22a The output is controlled to be a signal having a frequency that is an integral multiple of the reference frequency signal generated by the local oscillator 23.

In the frequency multiplication circuit 22, the frequency divider 22b
The frequency division ratio is variable, and if the frequency division ratio is changed, the frequency multiplication ratio of the frequency multiplication circuit 22 changes. When receiving a broadcasting station, the control means is arranged so that the broadcasting frequency of the broadcasting station is converted into the tuning frequency in the mixing circuit 21b.
25 sets the frequency multiplication rate of the frequency multiplication circuit 22. In this way, electronic tuning is performed and the target broadcasting station is received.

When broadcasting is not performed at the tuned frequency, the frequency multiplication circuit is controlled by the control means 25.
The frequency multiplication factor of 22 is reset to the value of another broadcasting station. The presence / absence of broadcasting is selected by the demodulation circuit 21 from the signals generated in the process of demodulation, and is determined by the broadcasting presence / absence determination circuit 24 based on the signal. Broadcast presence / absence determination circuit 24
A so-called squelch circuit is used in the. The determination result is fed back to the control means 25, and the tuning control is repeated until the broadcast can be received.

In the operation for judging the presence or absence of the broadcast,
Before the broadcast presence / absence determination circuit 24 outputs an accurate determination,
Further time is required after the frequency multiplication operation of the frequency multiplication circuit 22 becomes stable. Such time is uniformly secured by the control means 25. That is, the time (wait time) from when the frequency multiplication rate of the frequency multiplication circuit 22 is set by the control means 25 until the determination result of the broadcast presence / absence determination circuit 24 is checked is fixed in advance.

[0008]

In the electronic tuner, it is important to shorten the time for searching the broadcast by the above tuning control. If the time for searching the broadcast is long, the user feels uncomfortable between the time when the sweep search key is operated and the time when the broadcast is received until the broadcast search is instructed.

Of course, tuning accuracy is also important. In terms of tuning accuracy, not only the accuracy of the tuning frequency is important, but it is also extremely important that broadcasts that can be received are not skipped.

Conventionally, the key point for shortening the tuning time has been the rise time of the PLL (time for reaching the target value). And P
In order to shorten the rising time of LL, it is necessary to relax the high frequency suppression characteristic and the delay characteristic of the loop transfer function of PLL.

Specifically, it has been necessary to mitigate the high frequency suppression characteristic and the delay characteristic of the low pass filter which constitutes the PLL. However, if the high frequency suppression characteristic and the delay characteristic of the low pass filter are alleviated, a high frequency signal that is not removed is transmitted in the loop, and the phenomenon that the PLL fluctuates (vibrates) with respect to the target value is likely to occur. Further, the PLL may be out of synchronization due to a disturbance such as temperature.

This fluctuation appears as a deterioration in tuning frequency accuracy, and as a result, it lengthens the convergence time of the PLL. If the tuning control is performed due to the delay in the convergence time and the squelch circuit does not have sufficient time to determine the presence / absence of broadcasting, there is broadcasting at the frequency being tuned. However, there is a problem that the broadcast is skipped without being received.

As described above, since the PLL has the property that the tuning speed and the tuning accuracy are contradictory to each other,
It is necessary to set a good compromise between the proper rise time of the PLL and the proper convergence accuracy. However, it is not easy to accurately predict the PLL characteristics, it is necessary to study the stability of the PLL operation, and it is a fact that a lot of design man-hours are required to set a compromise point.

In particular, in a radio receiver which can be shipped to a plurality of countries and which is capable of complying with different radio regulations, the tuning conditions may differ depending on the radio regulations of the destination, and the analysis of the PLL characteristics can be further performed. Since it is not easy, it is unclear whether the length of the wait time uniformly set as described above is essential.

The technical problem of the present invention is to pay attention to such a problem, and in a radio receiver for electronic tuning, tune by eliminating an extra wait time while maintaining sufficient tuning accuracy. To save time.

[0016]

FIG. 1 is a block diagram showing the principle of a radio receiver according to the present invention. The radio receiver according to the present invention also includes the reference frequency oscillating means 3 for generating the reference frequency signal, the frequency multiplying means 2 for controlling the frequency multiplication rate and for multiplying the frequency of the reference frequency signal generated by the reference frequency oscillating means 3. A demodulation means 1 for demodulating a baseband signal by receiving a radio signal, mixing the reference frequency signal multiplied by the frequency multiplication means 2 with the reception signal, and converting the reception frequency into a tuning frequency to perform tuning to demodulate a baseband signal; , And a broadcast presence / absence determining means 4 for determining presence / absence of broadcast based on a signal output in the process of demodulating the baseband signal.

In such a configuration, the radio receiver of the present invention sets the frequency multiplication rate of the frequency multiplication means 2 according to the broadcasting frequency of the broadcasting station, and selectively selects the baseband signals of different broadcasting stations. Control means 5 for demodulation by the demodulation means 1, tuning condition storage means 6 for storing tuning conditions including at least wait time,
A tuning condition selecting means 7 for selectively setting a tuning condition, and the control means 5 selects a wait time stored in the tuning condition storing means 6 according to the selection setting of the tuning condition selecting means 7, When the frequency multiplication rate of the frequency multiplication means 2 is changed,
After the wait time has elapsed, there is a procedure for checking the determination result output by the broadcast presence / absence determining means 4.

[0018]

[Operation] It was found that the determination time of presence or absence of broadcasting is correlated with the frequency between stations. The relationship is that if the inter-station frequency is relatively small, the determination time needs to be relatively long, while if the inter-station frequency is relatively large, the determination time may be relatively short. Then, it has been found that, in the radio receivers exported to a plurality of countries, the length of the wait time, which has been uniformly set in the past, is not essential depending on the destination because of this relationship.

Since the radio receiver of the present invention has the tuning condition storage means 6 for storing the tuning condition including at least the wait time, the essential wait time according to the destination such as the above relationship is stored. can do.

In the radio receiver of the present invention, the tuning condition selecting means 7 for selecting and setting the tuning condition and the wait time is selected in accordance with the selection setting, and the frequency multiplying factor of the frequency multiplying means 2 is changed. When the wait time has elapsed, the control means 5 for checking the determination result output by the broadcast presence / absence determination means 4 when the wait time has elapsed
have. As a result, by setting the above selection settings according to the destination, the required wait time according to the destination is selected, and since the necessary and sufficient wait time is secured in such a way, tuning is accurate, and Unlike the prior art, the extra wait time is eliminated according to the destination, so the tuning time is shortened.

[0021]

EXAMPLES Next, examples of how the radio receiver according to the present invention is actually embodied will be described. Figure 2
FIG. 3 is a block diagram illustrating an embodiment of the present invention. High-frequency receiver circuit 11a, mixing circuit 11b, intermediate amplifier circuit 11c, detector circuit 11d, squelch circuit 11f, oscillator 12c, phase comparator 12b, low-pass filter 13, voltage-controlled oscillator 11e, frequency divider 12a constituting a synthesizer receiver circuit. For, the same circuit as the conventional one may be used.

It is preferable to use the CPU 12e as the tuning control means. ROM12f has CPU12e
The program to be executed by and the tuning conditions including the wait time are written in advance. The tuning conditions include the inter-station frequency, the reception frequency range, and the like in addition to the wait time.

Output of squelch circuit 11f and I / O port 12d
By connecting with, the CPU 12e can read the output of the squelch circuit 11f, that is, the presence or absence of broadcasting.
Input line and I / O port that control the division ratio of divider 12a
By connecting 12d, the oscillation frequency of the voltage controlled oscillator 11e can be controlled by the CPU 12e.

The tuning condition selection circuit 18 is constructed by using a land to which a jumper wire can be attached, a key matrix, a DIP switch, etc., and the circuit is an I / O port.
Connect to 17 to allow CPU 12e to read its settings.

FIG. 3 is an example of a flow chart for explaining the tuning control procedure by the CPU 12e, which is an embodiment of control for sweeping the reception frequency from the lower frequency to the higher frequency to search the broadcast. In step H11, the setting of the tuning condition is read and the wait time T _WT is selected according to the setting.

The frequency division ratio corresponding to the sweeping reception frequency is
The minimum value is set by step H12, and step H18
It increases with each inter-station frequency. Then, the reception range is checked in step H19. If the reception range is exceeded, the process returns to step H12 and the reception frequency is set to the minimum value. If you support multiple destinations,
Minimum value of received frequency in step H12, step H
The inter-station frequency in 18 and the reception range in step H19 may be set as tuning conditions, that is, the destination setting may be read and selected as a value according to the setting.

In step H13, the frequency division ratio of the PLL is set. After setting the division ratio, step H
The wait time T _WT selected in 11 is secured in step H14. When the wait time T _WT has elapsed after setting the frequency division ratio, the output of the squelch circuit is checked as in step H15.

If there is no broadcast, steps H18, H
Repeat the sweep as in 19. If there is a broadcast, stop the sweep there and wait until the next sweep operation, as in step H20. In order to prevent the sweep from being stopped because all broadcasts have ended, it is preferable that the sweep can be forcibly stopped by a switch operation or the like, as in step H17.

[0029]

As described above, since the radio receiver according to the present invention is constructed so as to select the necessary and sufficient wait time in accordance with the destination in tuning control, the tuning becomes accurate and the conventional method. Unlike the above, the extra wait time is eliminated, so the tuning time is also shortened.

Therefore, according to the present invention, in a radio receiver for electronic tuning, it is possible to eliminate the extra wait time and shorten the tuning time while maintaining sufficient tuning accuracy. became.

In the conventional case, as described above,
Although the contradictory characteristics of tuning speed and tuning accuracy have been set to appropriate compromises by changing the transfer function characteristics of the PLL, a lot of design man-hours have been spent, but it has been sufficiently tested and adjusted. There is also a method in which the above-mentioned compromise is set by repeatedly utilizing a PLL circuit whose characteristics have become known and adjusting the wait time instead of changing the characteristics of the PLL.

On the other hand, according to the present invention, since the wait time can be selectively set as described above, the wait time can be adjusted very easily. It has become possible to reduce the design man-hours by applying it.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram illustrating an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a tuning control procedure in the embodiment.

FIG. 4 is a block diagram of a conventional radio receiver.

[Explanation of symbols]

 1 demodulation means 2 frequency multiplication means 3 local oscillation means 4 broadcast presence / absence determination means 5 control means 6 tuning condition storage means 7 tuning condition selection means

Claims (1)

[Claims] 1. A reference frequency oscillating means (3) for generating a reference frequency signal, and a frequency multiplying means capable of controlling a frequency multiplication rate and multiplying the frequency of the reference frequency signal generated by the reference frequency oscillating means (3). (2) and a radio signal is received, and tuning is performed by mixing the reference frequency signal multiplied by the frequency multiplication means (2) with the reception signal and converting the reception frequency into a tuning frequency. Radio reception having demodulation means (1) for demodulating the signal and broadcast presence / absence determination means (4) for determining presence / absence of broadcasting based on a signal output in the process of demodulating the baseband signal by the demodulation means (1). In this system, the frequency multiplication rate of the frequency multiplication means (2) is set according to the broadcasting frequency of the broadcasting station, and the baseband signals of different broadcasting stations are selectively demodulated by the demodulation means (1). Means (5), tuning condition storage means (6) for storing tuning conditions including at least wait time, and tuning condition selection means (7) for selectively setting tuning conditions, wherein the control means (5) is , The tuning condition selecting means
Tuning condition storage means according to the selection setting of (7)
When the wait time stored in (6) is selected and the frequency multiplication rate of the frequency multiplication means (2) is changed, the broadcast presence / absence determination means (4) outputs after the wait time has elapsed. A radio receiver having means for checking a judgment result.