JPH0355923A - Control method for local oscillation circuit of receiver - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of an oscillating frequency due to temperature change by providing a temperature sensor and a memory, comparing the temperature at preceding and this operation for each intermittent operation, and stopping the intermittent operation of a phase locked loop at reception when a prescribed temperature change or over is recognized. CONSTITUTION:When a PLL is locked in intermittently and a voltage controlled oscillator VCO is subject to free run at a point of time of the synchronization is obtained, if a rapid temperature change exists, the oscillating frequency of the VCO not PLL-locked is fluctuated due to temperature. Then intermittent temperature detection is applied in a temperature detection comparison block, the temperature of preceding PLL lock-in and the temperature at present are compared. When there is a prescribed difference or over in the both, the PLL loop is not interrupted but the lock-in state is kept over a period to be received continuously. Thus, the fluctuation in the oscillating frequency due to a temperature change is suppressed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a local oscillation circuit I for a receiver that saves power consumption.
Concerning improvements in control methods. (Prior Art) In recent years, radio devices using synthesizer-type local oscillation circuits have come into widespread use as mobile communication radio devices. Figure 3 is a block diagram showing an example of a receiver using a conventional synthesizer-type local oscillator. The receiver shown in this figure includes a receiving section 102 that reproduces a radio signal received by a receiving antenna 101, and a P L. L, method local oscillation circuit {
It is equipped with 03.

The local oscillator circuit +03 connects the phase comparator 106, the low-pass filter 107% VC0108, and the variable frequency divider lO5 in series in a loop, and also feeds back the output of the reference oscillator 104 to the other input terminal of the phase comparator 106. At least it is an open loop configuration. Then, this receiver amplifies the radio signal received by the receiving antenna 101 with the high frequency amplifier 110, and then converts it into an intermediate frequency signal IF using the local oscillation signal from the local oscillation circuit 103 with the mixing circuit III. Demodulates and reproduces the data in the signal. By the way, ordinary radio equipment used for mobile communication is composed of many logic elements, and these elements,
In particular, the elements constituting the local oscillation circuit 103 are constantly energized to constantly wait for incoming calls from the other party. For this reason, there was a problem in that power was consumed even when there was little transmission or reception. For this reason, there has traditionally been a method of turning off the power to a part of the receiver during reception standby and turning on the power when detecting an incoming signal, but even in this case, the power to the local oscillator must be turned off. possible, and it is necessary to supply power continuously. Therefore, since the synthesizer-based local oscillator described above consumes more power, there is a problem in using it in a small portable device equipped with a small-capacity battery. Furthermore, in the case of small beagers, a framing calling method is adopted to reduce current consumption and increase the selection signal as a result, and each beger is activated for a short period of about 2 seconds at a specific timing, for example every 30 seconds. There is a system in which the beijer is called, and each beijer turns on power to its receiver in synchronization with the timing when its own station is called. However, even in such receivers, operating the PLL during the self-calling period increases current consumption, and there is a strong demand for further extension of battery life.

In order to solve this problem, the same applicant has already
The LL oscillator is synchronized only for a short period of time during the ringing period of the receiver concerned, and the VCO is activated immediately after the oscillation frequency is synchronized.
An application has been filed for an invention in which all other operations are stopped and thereafter free running is performed asynchronously (Japanese Patent Application No. 1-12474). However, in this method, if there is a large temperature change during the VCo free running, PLL loop out-of-sync may occur. There was a drawback that the oscillation frequency of the VCO fluctuated, causing the receiving frequency to shift, and in severe cases, to make reception impossible. To explain this simply, as shown in Figure 5, 32
In this case, 2 seconds out of every second is set as a calling frame for the own receiver, power is supplied to the receiver only for the 2 seconds, and power is turned off for the remaining 30 seconds. The time to turn on the PLL oscillator within the above 2 seconds is the first 100m of the period.
Let us consider the case where the remaining +900 msl; tVco is received while free running. According to this method, P
Since the time to turn on LL is extremely short (rooms), current consumption can be significantly reduced. However, if there is a sudden temperature change as shown in Figure 6(a) during this free running period of vCO, then
), the oscillation frequency of the vCO fluctuates, and if the fluctuation becomes large, there is a risk that it will deviate from the reception band and become unreceivable. In addition, the figure (c) shows 100 ms when the PLL is turned on.
This shows the period of y. (Object of the Invention) The present invention has been made to eliminate the above-mentioned drawbacks of the conventional technology, and is to prevent frequency fluctuations during free run of the vCO in order to reduce power consumption in the local oscillator circuit. The purpose of this paper is to provide a method for controlling the local oscillator circuit of a receiver. (Summary of the Invention) In order to solve the problems mentioned above, in the local oscillator circuit control method of a receiver according to the present invention, the local oscillator circuit is The circuits other than the VCO among the phase-locked circuits constituting the oscillation circuit are stopped and the VCO is maintained during the period.
A receiver that uses CO in asynchronous free-running oscillation detects a change in environmental temperature, and if the amount of change exceeds a predetermined value, the operation of the phase-locked circuit is not stopped.
It is characterized by operating the entire PLL and preventing fluctuations in the oscillation frequency due to temperature changes. (Example) Hereinafter, the present invention will be explained in detail based on an illustrated example. FIG. 1 is a block diagram showing one embodiment of the present invention. The receiver shown in this figure includes a receiving antenna l, a receiving section 2 that reproduces the received signal, a speaker 3 that outputs the reproduced signal as sound, a local oscillation circuit 4 that generates a local oscillation signal, and a power switch 5. It is equipped with Furthermore, the local oscillation circuit 4 includes a VCO that generates a local oscillation signal.
6 (voltage controlled gJg oscillator) and ;: f) V C
The VCO control unit 7 that controls the oscillation frequency of 06 and this
It includes a switch section 8 inserted between the CO control section 7 and the VCO 6, and an oscillation control section 9 that controls the switch section 8 and the VCO control section 7. The VCO control unit 7 also includes a reference oscillator 10 that generates a reference signal, a reference frequency divider 20 that divides the output of the reference oscillator IO, and a fixed frequency divider that divides the local oscillation signal output from the VCO 6. a frequency divider II; a variable frequency divider 12 for further dividing the frequency signal divided by the frequency divider II; A phase comparator +3 that compares the phase of the output signal of the variable frequency divider l2 and the phase of the reference signal output from the reference frequency divider 20.
and a charge pump circuit l4 that generates a frequency control voltage based on the output of the phase comparator l3 and supplies it to the switch section 8. Further, the switch section 8 has a switch l5 that closes when the output signal is output from the oscillation control section 9, and holds the frequency Ill control voltage supplied via the switch l5 when the switch l5 is closed. Voltage holding circuit that supplies the vCO6! 6. The oscillation control section 9 also includes a switch l7 that turns on and off the power supply to the VCO control section 7, a data generator 18 that generates a set frequency division ratio designation signal and supplies it to the variable frequency divider l2, and the reception It is provided with a data generator 18 and a timing generation circuit 19 that controls the switches 15 and 17 according to the receiving state of the section 2. Furthermore, a temperature detection comparison block 30 is provided, which block includes temperature sensors 31 . A/D (analog digital converter)
32, a CPU 33, and a memory 34. Next, the operation of this embodiment will be explained with reference to FIG.

First, when the power switch 5 is closed, power is supplied to each part of the receiver and the radio starts operating. During reception standby until the receiving unit 2 receives a wireless signal from the other party, that is, while it is in a reception standby state, the timing generation circuit 19 operates at the time IIt as shown in FIG.
．． Close switch +7 only for O and turn on VCOitll @ section 7
At the same time, the data generator 18 is operated and a division ratio designation signal is supplied to the vCO control unit 7. As a result, the VCOflll controller 7 can adjust the phase of the reference signal obtained by the internal reference oscillator 10 and the VCOflll controller 7.
It compares the phase of the local oscillation signal output from CO6 and generates a frequency control voltage corresponding to the comparison result. At the same time, the timing generation circuit 19 closes the switch 15 to connect the vCO control section 7 and the vcoe. As a result, the phase synchronization system loop is closed and the VCO control g
The frequency control voltage obtained by the l section 7 is transferred to the switch section 8.
VCO6 is supplied to the VCO6 through the reference oscillator output, and the reference oscillator output is synchronized with the VCO6, and its frequency becomes the one set in the data generator l8. Once the frequency control operation of the VCO 6 is completed and synchronization is established, the timing generation circuit I9 turns the switch +7 with lm< for a time ts, stops the operation of the data generator l8, and controls the VCO control section 7. Stop the operation completely. However, even if this vCO control unit 7 stops operating, the vCO
6 continues to output the local oscillation signal at the same frequency using the frequency control voltage held in the voltage holding circuit l6 of the switch section 8.

Thereafter, the timing generation circuit 19 repeatedly executes the above-described operation, and closes the phase synchronization system loop by a time to every time js elapses (thereby synchronizing the VCO 6 and the reference oscillator to change the frequency of the local oscillation signal). It is pulled back to the preset value. In this state, the receiving antenna l receives a wireless signal from the other party, and the receiving unit 2 detects the carrier wave (or single tone signal) and outputs a reception detection signal. Then, while this reception detection signal is being output, the timing generation circuit !9
With the switches l5 and l7 closed, the data generator l
Put 8 into operation. As a result, while the reception detection signal is being output,
Closing the loop of the above phase synchronization system and continuing the synchronization state, VC
Increase the stability of the local oscillation signal frequency of O6 and stabilize the reception operation of the receiver 2. After this, if the receiving antenna 1 no longer receives a wireless signal from the other party and the receiving section 2 stops outputting the reception detection signal, the timing generating circuit 19i
Open the back switch 15.17 and open the data generator l.
8 is stopped and the reception waiting operation is resumed.

In this way, in this embodiment, the operation of the CO control section 7 is periodically stopped by the timing generation circuit 9 when waiting for reception, so that the power consumption in the local oscillation circuit can be reduced. This allows the power consumption of the entire wireless device to be reduced.

Next, the operation when the environmental temperature suddenly changes in this state will be explained.

That is, when the PLI is intermittently locked in and the vCO is allowed to free run when synchronization is achieved, if there is a sudden temperature change, the oscillation frequency of the vCO whose PLL is not locked will fluctuate depending on the temperature.

Therefore, in the present invention, temperature is detected intermittently in the temperature detection comparison block shown in FIG. are compared, and if there is a difference of more than a predetermined value between the two, P L L. To operate so as to maintain a lock-in state over a period during which continuous reception is required without interrupting the loop.

As a result, even if there is a sudden temperature change, the oscillation frequency is accurately temperature-compensated due to the PLL lock effect.
Oscillator (oscillator part including crystal 10 and basic frequency divider 20)
Temperature changes are compensated for by following . Note that even during continuous PLL lock-in, performing the temperature comparison intermittently and starting the intermittent PLL lock operation as soon as no change in temperature is recognized will reduce consumption. It is effective in reducing current. Further, in the above-mentioned embodiment, when the receiving unit 2 receives the radio number 13 from the other party, the timing generating circuit l9 closes the switches 15 and 17 and operates the data generator l8. If the receiver is a breathtalk transceiver or the like operated together with the transmitter, switches l5 and l7 are closed during the entire communication period, and the data generator l8 is turned on and off.
It is also possible to improve the transmission and reception quality by causing the communication time to increase, and then periodically stop the operation of the CO control unit 7 again after the communication time has ended. Although the above embodiments have been explained in the case of a general communication device, the same idea is also effective in a bejar that employs a frame synchronous calling method.

As shown in FIG. 5, for example, in a Bejar receiver that repeats the receiving operation for only a certain period of 2 seconds out of 32 seconds, the above-mentioned PLL rotor state is established only for the first 100 msec of the receiving operation period, and synchronization is performed. After that, when the present invention is adopted in a device that stops the PLL lube,
Repeat PLI every 32 seconds, perform the above temperature detection and comparison during lock-in, and if a large change is found between the previous and current temperatures, PLL lock will be stopped for 2 seconds during which reception operation should be performed. All you have to do is operate it so that it continuously maintains a synchronized state without any problems. In addition, also in this case, the temperature detection comparison may be performed intermittently every 2 seconds as described above, and the PLL rule may be canceled when there is no longer a temperature change.

Further, even during vCO free running, temperature comparison may be performed intermittently or continuously, and the PLL may be locked in when a predetermined change is observed.

Furthermore, it is obvious that the present invention is not limited to the configuration of the above-mentioned embodiments, and that various modifications can be made in carrying out the present invention. (Effects of the Invention) As explained above, according to the present invention, it is possible to suppress fluctuations in the oscillation frequency caused by temperature changes when reducing power consumption in the local oscillator circuit, and thereby the entire radio device can reduce power consumption.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the receiver local oscillator circuit control method according to the present invention, FIG. 2 is a timing diagram showing an example of the operation of the same embodiment, and FIG. 3 explains the operation of the present invention. Time chart, Figure 4 is a block diagram showing an example of a conventional radio device, Figure 5 is a time chart diagram explaining the already applied invention, Figure 6 (a) (bl (c) is a time chart showing its defects) It is a diagram. 4. Local oscillation circuit, e-vco, 7. Circuits other than VCO (VCO I1 control section). 9. Oscillation control section. 30. Temperature detection comparison block 3l.. Temperature sensor 34...Memory

Claims (1)

[Scope of Claims] A receiver using a phase-locked circuit in which a phase comparator, a low-pass filter, and a voltage-controlled oscillator are connected in a loop as a local oscillator, and a reference oscillator is connected to the phase comparator, the receiver comprising at least During reception standby, a local oscillation circuit that operates all or part of the other blocks except for the voltage controlled oscillator intermittently at a required cycle is equipped with a temperature sensor and a memory device, and each time it operates intermittently, it detects the previous operation. A local oscillation circuit of a receiver, characterized in that the local oscillation circuit of the receiver is configured to compare the current temperature with that of the present time, and to stop the intermittent operation of the phase-locked circuit loop during reception if a temperature change of more than a predetermined value is observed. Control method.