JPH03162018A - frequency stabilizer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a car telephone device, a local cordless telephone device,
Frequency correction devices used in MCA radio equipment, etc., and radio equipment such as MCA radio equipment are equipped with a synthesizer that outputs a signal at a local oscillation frequency in order to transmit and receive a radio signal at a desired frequency. A high frequency signal and a local oscillation frequency signal are mixed and converted into first and second intermediate frequency signals and a low frequency signal, and in the case of transmission, a low frequency signal and a second intermediate frequency signal are mixed.
, is configured to convert the first intermediate frequency signal and the local oscillation frequency signal into a high frequency signal of a desired frequency.

A synthesizer uses a temperature controlled crystal oscillator (TCXO) that generates a reference frequency signal, and locks the reference frequency signal from this temperature controlled crystal oscillator to generate a high frequency band (RF) signal.
The PLL circuit is generally composed of a PLL circuit that outputs a signal at a local oscillation frequency, and a voltage controlled oscillator (VCO) that outputs a signal at a local oscillation frequency, and a
It consists of a phase comparator that outputs a signal according to the phase difference between the signals from the O and the temperature-controlled crystal oscillator, and a loop filter that converts the signal according to this phase difference into a voltage and outputs it as a control signal for the VCO. Ru.

Here, the frequencies generated by the temperature controlled crystal oscillator (TCX○) and voltage controlled oscillator (VCO) fluctuate due to temperature changes and changes over time, so by switching hardware such as RC circuits, the temperature controlled crystal oscillator (TCX ) and voltage controlled oscillators (VCOs).

Problems to be Solved by the Invention However, in the above conventional frequency stabilizing device, the RC
Since hardware such as circuits is switched, for example, the control voltage is controlled in a stepwise manner, and therefore, there is a problem that the frequency cannot be optimally stabilized.

The present invention solves the above conventional problems, and aims to provide a frequency stabilizing device that can optimally stabilize a transmission frequency.

Means for Solving the Problems In order to achieve the above object, the present invention includes an oscillator that generates a reference frequency of a transmitted wave according to a control voltage, and means for measuring the frequency of a received wave, so that a CPU can measure the frequency of the received wave. The reference frequency of the oscillator is calculated based on the frequency of , and a control voltage corresponding to the reference frequency is applied to the oscillator.

According to the above structure, the frequency of the received wave and the transmitted wave have a certain relationship, and since the frequency of the received wave is transmitted based on the accurate reference frequency of the base station, the frequency of the received wave is transmitted based on the accurate reference frequency of the base station. Frequency can be calculated.

Also, does the CPU control the oscillator? Since the n voltage is controlled, the transmission frequency can be controlled in real time, and therefore the transmission frequency can be optimally stabilized. Furthermore, even if the control voltage characteristics of the oscillator change, the CPU counts the reference frequency of the oscillator, so that the transmission frequency can be optimally stabilized.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
FIG. 2 is a block diagram showing an embodiment of the frequency stabilizing device according to the present invention, and FIG. 2 is a flowchart for explaining the operation of the CPU shown in FIG. 1.

In FIG. 1, reference numeral 1 indicates a second intermediate frequency (
The counter 2 that counts IP) is a counter that counts the second local oscillation frequency (Local) for converting the first intermediate frequency to the second intermediate frequency. Therefore, since counter 1 counts the second intermediate frequency proportional to the received wave, it can detect the frequency of the received wave, and counters l and 2 each count the second intermediate frequency proportional to the received wave. Since the frequency and the second local oscillation frequency are counted, an inexpensive configuration is sufficient.

3 is a temperature controlled crystal oscillator (TCXO) that generates a reference frequency for a synthesizer (not shown) according to a control voltage.
This reference frequency is output to a phase comparator (not shown) of the synthesizer. The synthesizer is the first
, generates a signal at the second local oscillation frequency, and the receiving section mixes the high frequency signal and the signal at the local oscillation frequency to convert it into first and second intermediate frequency signals and a low frequency signal, and the transmitting section (not shown) converts the low frequency signal, the second and first intermediate frequency signals, and the local oscillation frequency signal into a high frequency signal of a desired frequency.

4 is a timer that resets counters 1 and 2 at predetermined time intervals using the output signal of temperature-controlled crystal oscillator 3 as a clock, and 5 is a temperature-controlled crystal oscillator according to the count values of counters 1 and 2, as described later. The CPU 5 is a central processing unit (cpU) that controls the control voltage of the counter 1.
, 2, and a memory having an area for storing count values of 2 and other work areas. 6 is CPU! This is a D/A converter for converting the voltage controlled by 5 into an analog value and applying it to the temperature controlled crystal oscillator 3.

Next, referring to FIG. 2, we will explain the operation of the above embodiment, especially the CPU.
The operation of step 5 will be explained.

In FIG. 2, counters 1 and 2 start counting the second intermediate frequency and second local oscillation frequency (step 11), and when they finish counting (step 12), counters 1 and 2 start counting the second intermediate frequency and second local oscillation frequency, respectively. The values of the second intermediate frequency and the second local oscillation frequency are read and stored in the memory area ASB (steps 13 and 14).

Next, for example, the frequency X is calculated using the following formula: ), a control voltage Y such that the frequency X becomes "O" is applied to the temperature controlled crystal oscillator 3 via the D/''A converter 6.

Therefore, according to the above embodiment, the CPU 5 calculates the frequency Since the control voltage Y of the temperature controlled crystal oscillator 3 is calculated according to X, the reference frequency of the temperature controlled crystal oscillator 3 is controlled in real time, and therefore the transmission frequency can be optimally stabilized.

Effects of the Invention As explained above, the present invention includes an oscillator that generates a reference frequency of a transmitted wave according to a control voltage, and a means for measuring the frequency of a received wave, and a CPU controls the frequency of the oscillator based on the frequency of the received wave. Since the reference frequency is calculated and a control voltage corresponding to the reference frequency is applied to the oscillator, the transmission frequency can be controlled in real time, and therefore the transmission frequency can be optimally stabilized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a frequency stabilizing device according to the present invention, and FIG. 2 is a flowchart for explaining the operation of the CPU shown in FIG. 1.2... Counter, 3... Temperature controlled crystal oscillator (
TCXO), 5... central processing unit (CPtJ), 6.
・D,/A converter. Sui 1 Figure A- 2nd intermediate lIl Qing number B-121! The voltage between the i and jk systems is

Claims (3)

[Claims] (1) an oscillator that generates a reference frequency of a transmitted wave according to a control voltage; a means for measuring the frequency of a received wave; and a reference frequency of the oscillator calculated from the frequency of the received wave measured by the measuring means; A frequency stabilizing device comprising: a CPU that applies a control voltage according to a reference frequency to the oscillator. (2) The frequency stabilizing device according to claim 1, wherein the measuring means measures the second intermediate frequency of the received signal. (3) The measuring means measures a second intermediate frequency and a second local oscillation frequency of the received signal.
1) The frequency stabilizing device described above.