JP2002124875A - Local oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a highly stabilized output frequency even when the output frequencies of a plurality of local oscillators are different and to synchronize the plurality of local oscillators. SOLUTION: A GSP receiver 10 generates a highly stabilized reference signal on the basis of a signal received from a GPS satellite 14, and it outputs the signal to a PLL circuit 11. On the basis of the reference signal, the PLL circuit 11 outputs a signal at a desired frequency on the basis of a frequency division ratio which is set in advance by a frequency division ratio setting circuit 13, and the signal is amplified by an amplifier circuit 12 so as to be output as the output signal of a local oscillator 15. Even when the output frequency of the local oscillator 15 is changed, the output frequency can be changed easily by changing the setting of the frequency division ratio of the setting circuit 13. Even when the output frequency of the local oscillator 15 is changed in this manner, the output frequency of the local oscillator is stable because it depends on the reference signal to be output by the GPS receiver 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a PLL (Phaseed L).
More particularly, the present invention relates to a local oscillator that outputs a highly stable frequency signal and can synchronize among a plurality of local oscillators.

[0002]

2. Description of the Related Art Conventionally, a local oscillator provided on a receiver side is:
The output signal of the local oscillator is generated by using a crystal oscillator as a reference signal source and multiplying the signal of the crystal oscillator. Even when there are a plurality of local oscillators, each of the local oscillators is independently operated by an individual crystal oscillator.

[0003]

However, in the above-mentioned conventional configuration, when the frequency of the output signal of the local oscillator is different, a crystal oscillator having a different oscillation frequency must be prepared. Is required, a highly stable crystal oscillator must be prepared for each output frequency, so that the local oscillator becomes expensive. Further, when there are a plurality of local oscillators, since each of the local oscillators is independently operated by an individual crystal oscillator, the plurality of local oscillators cannot be operated in synchronization.

The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a highly stable output frequency easily even when a plurality of local oscillators have different output frequencies, and to provide a plurality of local oscillators. The purpose is to achieve synchronization between oscillators.

[0005]

In order to solve the above problems, a local oscillator according to the present invention uses a PLL circuit,
A local oscillator that generates an output signal that is phase-synchronized with an input signal and includes a GPS receiver that receives a signal from a GPS (Global Positioning System) satellite, and a reference signal of a PLL circuit is an output signal from the GPS receiver. Is used.

That is, the local oscillator according to the present invention comprises a PLL
By using a GPS receiver as a circuit and a reference signal source of this PLL circuit, the output frequency is made highly stable, and synchronization is achieved between a plurality of local oscillators.

Further, the local oscillator according to the present invention, in the above invention, comprises a frequency division ratio setting circuit which can arbitrarily set a frequency division ratio of an output frequency of the PLL circuit, and a desired frequency is set by setting the frequency division ratio setting circuit. It is characterized by outputting a frequency signal.

That is, according to the local oscillator of the present invention,
Even when the output frequency of the local oscillator is changed, the output frequency of the local oscillator can be easily changed by changing the setting of the division ratio of the division ratio setting circuit. Of course, even when the output frequency of the local oscillator is changed in this way, the output frequency of the local oscillator is always stable because it depends on the reference signal output from the GPS receiver.

Further, the local oscillator of the present invention can be used for a frequency conversion circuit that converts an input frequency to a desired frequency and outputs the converted frequency, and can also be used for a relay broadcaster using this frequency conversion circuit.

Furthermore, the present invention can be used for a relay broadcasting system that uses a plurality of relay broadcasters and performs a synchronous operation between the plurality of relay broadcasters. It can also be used for a wave digital television relay broadcasting system.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The local oscillator according to the present invention is characterized in that a PLL circuit and a GPS receiver are used as a reference signal source of the PLL circuit. According to the local oscillator of the present invention, the PLL circuit and the reference signal source of the PLL circuit have G
By using the PS receiver, the output frequency of the local oscillator becomes highly stable, and it becomes possible to synchronize the plurality of local oscillators.

An embodiment of a local oscillator according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a local oscillator according to an embodiment of the present invention. In the figure, a local oscillator 15 includes a GPS receiver 10 for receiving a reference signal from a GPS satellite 14, a PLL circuit 11 for synchronizing a phase of an input signal and an output signal, and a PLL circuit 1
A frequency division ratio setting circuit 13 for setting a frequency division ratio of a frequency of 1;
An amplification circuit 12 amplifies and outputs an output signal of the PLL circuit 11.

The GPS receiver 10 is a GPS satellite 1
A high-stability reference signal is generated based on the signal received from the control circuit 4 and the reference signal is output to the PLL circuit 11. Then, based on the reference signal, the PLL circuit 11
A signal having a desired frequency is output based on the frequency division ratio set by the frequency division ratio setting circuit 13, amplified by the amplifier circuit 12, and output as an output signal of the local oscillator 15.

At this time, even if the output frequency of the local oscillator 15 is changed, the output frequency of the local oscillator 15 can be easily changed by changing the setting of the dividing ratio of the dividing ratio setting circuit 13. Can be. Even when the output frequency of the local oscillator 15 is changed as described above, the output frequency of the local oscillator is set to
Since it depends on the reference signal output from the PS receiver 10, it is always stable.

That is, according to the local oscillator 15 of the present invention, the signal from the GPS satellite 14 having high frequency stability can be obtained without preparing a crystal oscillator having a different oscillation frequency every time the frequency of the output signal is different. By setting the frequency division ratio of the frequency division ratio setting circuit 13 as a reference signal, the local oscillator 15 can output a signal of a desired frequency.

FIG. 2 is an example of a system diagram showing a relay broadcast system using the local oscillator of FIG. In the figure, two relay broadcasters 19a and 19b respectively incorporate local oscillators 15a and 15b and
The signal from the satellite 14 is received.

That is, the relay broadcaster 19a includes a local oscillator 15a having a configuration shown in FIG. 1, a receiving circuit 16a for receiving a broadcast wave, and a frequency for converting a frequency of the broadcast wave received by the receiving circuit 16a into a desired frequency. A conversion circuit 17a and a power amplifying unit 18 for amplifying and outputting a broadcast wave of a desired frequency
a.

Similarly, the relay broadcaster 19b also includes a local oscillator 15b having the configuration shown in FIG. 1, a receiving circuit 16b for receiving a broadcast wave, and converting the frequency of the broadcast wave received by the receiving circuit 16b to a desired frequency. A frequency conversion circuit 17b,
Power amplifier 1 for amplifying and outputting a broadcast wave of a desired frequency
8b. Note that a plurality of frequency conversion circuits 17a and 17b may be provided.

The relay broadcasters 19a and 19 having such a configuration are described.
b, there are two local oscillators 15a, 15
Since the reference signal b is dependent on the signal received from the GPS satellite 14, the relay broadcasters 19a and 19b
Output frequency (that is, each power amplifying unit 18a, 18
b output frequency).

The embodiment described above is an example for describing the present invention, and the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention. is there. For example, the number of relay broadcasters shown in FIG. 2 is not limited to two, and a plurality of relay broadcasters
Synchronization can also be performed by a received signal from a PS satellite. Furthermore, a relay broadcast system using a plurality of relay broadcasters can be constructed as a terrestrial digital television relay broadcast system. Even in such a terrestrial digital television relay broadcasting system, SFN (Singing
le Frequency Network: single frequency network) can be easily realized.

[0021]

As described above, according to the local oscillator of the present invention, the PL is controlled based on the reference signal from the GPS satellite.
Since the output signal is generated by the L circuit, the output frequency can be made highly stable, and synchronization among a plurality of local oscillators can be easily obtained. That is, even if the output frequency of the local oscillator is changed, it is possible to easily and stably output at a desired output frequency, and even when there are a plurality of local oscillators, each local oscillator can be easily output. Can be synchronized. Moreover, since it is not necessary to use an expensive crystal oscillator having a different oscillation frequency for each output frequency of the local oscillator, an inexpensive local oscillator can be provided. Therefore, if the local oscillator of the present invention is used, it can be widely applied to various circuits that handle stable frequencies, for example, AFC circuits, AM / FM demodulation circuits, and transceivers of synthesizers and television receivers.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a local oscillator according to an embodiment of the present invention.

FIG. 2 is an example of a system diagram showing a relay broadcast system using the local oscillator of FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 GPS receiver 11 PLL circuit 12 Amplification circuit 13 Division ratio setting circuit 14 GPS satellite 15, 15a, 15b Local oscillator 16a, 16b Receiving circuit 17a, 17b Frequency conversion circuit 18a, 18b Power amplification section 19a, 19b Relay broadcaster

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Makoto Nishio 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 5J106 KK05 PP03 QQ12 RR01 5K072 AA21 BB01 BB27 BB25 BB27 CC06 CC31 FF20

Claims (6)

[Claims] 1. A local oscillator for generating an output signal in phase with an input signal using a PLL circuit, comprising: a GPS receiver for receiving a signal from a GPS satellite, wherein a reference signal of the PLL circuit is A local oscillator using an output signal from the GPS receiver. 2. A frequency division ratio setting circuit that can arbitrarily set a frequency division ratio of an output frequency of the PLL circuit, and outputs a signal of a desired frequency by setting the frequency division ratio setting circuit. The local oscillator according to claim 1, wherein 3. The local oscillator according to claim 1, wherein the local oscillator is used for a frequency conversion circuit that converts an input frequency into a desired frequency and outputs the converted frequency. 4. The local oscillator according to claim 3, wherein the local oscillator is used in a relay broadcaster using the frequency conversion circuit. 5. The local oscillator according to claim 4, wherein the local oscillator is used in a relay broadcast system that uses a plurality of the relay broadcasters and performs a synchronous operation among the plurality of relay broadcasters. 6. The local oscillator according to claim 5, wherein the local oscillator is used in a terrestrial digital television relay broadcasting system constructed using the relay broadcasting system.