JPH0252465B2 - - Google Patents

Abstract

PURPOSE:To stop the supply for unnecessary circuits such as a voice circuit and to reduce the current consumption of power by stopping a PLL control oscillating circuit requiring comparatively much power supply current comsumption at the standby reception where reception state is continued for a long time. CONSTITUTION:While a PLL oscillating circuit is in operation, an output frequency fO of a VCO11 is frequency-divided by a prescaler 12, variable frequency division is applied further by a programmable frequency divider 13, the phase is compared with a reference frequency fr at a phase comparator 14 and its phase difference output locks the oscillating frequency of the VCO11 as a control DC voltage. The operation of the PLL circuit 1 is stopped at the standby reception state, an output fR of a fixed frequency oscillator 15 exclusive use of standby reception is used directly or used while being multiplied at a multiplier 18, the frequency fR of the oscillator 15 is frequency-divided by a frequency divider 17 at the operation of PLL as the use of the reference frequency fr. The power supply is switched by a PLL power switch S2 in interlocking with fO and fO'.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a multi-purpose receiver for portable, vehicle-mounted, and remote areas where electric light power is not available, and is used for communication, emergency calls, etc. when not in use. The purpose of this invention is to reduce the consumption of the power supply battery by applying it to a receiver that must always maintain a reception standby state for reception and reception.

[Conventional technology and problems]

Receivers for mobile use or for use in remote areas where electric light power is not available often use dry batteries as a power source, and the operating time depends on the battery life, but especially for portable use, it is recommended to use a small size as much as possible in terms of weight and volume. Since the use of batteries is desired, the current consumption (i.e. power consumption) must be designed to be as small as possible, but the current required to maintain the performance of the receiver must be secured, so it is not possible to use batteries for communication or emergency calls. Conventionally, means have been implemented to reduce current consumption by stopping the operation of the audio amplification circuit after the received wave detection stage by using, for example, a squelch control voltage during standby and reception. However, since the audio output stage that consumes the most current is normally in Class B operation, the current consumption is small when there is no input, so the savings effect of stopping the operation of the audio output stage is not necessarily sufficient. Ta.

As a system that improves this, there is a Japanese Patent Application No. 90444 filed in 1982, ``Method for reducing current consumption during standby'', which was previously filed by the present applicant. The outline of the invention is (1)
In a wireless receiver that sets the reception frequency using a phase-locked loop controlled local oscillator,
A method for reducing current consumption during standby, characterized by a configuration in which the operation of the phase-locked loop circuit is stopped during standby for reception of radio waves of a specific frequency, and a fixed frequency oscillator exclusively for standby and reception is used instead. (2) Connect the phase-locked loop control local oscillator output and the crystal-controlled local oscillator output in parallel, turn off the power to the crystal-controlled oscillator during "normal reception", and turn off the phase-locked oscillator during "standby reception". (3) The output of the crystal controlled oscillator that constitutes the local oscillator in the phase-locked loop control local oscillator circuit is configured to turn off the power to the locked loop oscillator. There is a configuration in which the power is switched to the mixer of the receiving circuit, and the power is turned off to the local oscillation circuit under phase-locked loop control except for the crystal-controlled oscillator. However, in (2) above, the crystal control for standby reception is It is necessary to provide a separate oscillator, (3)
In some cases, this may not necessarily be true due to the frequency configuration, so it would be desirable to make further progress.

[Purpose of the invention]

The present invention aims to further expand the effect of reducing current consumption (power consumption) achieved by the prior art during standby reception, and to obtain a power consumption reduction method that does not involve deterioration of reception performance.

[Summary of the invention]

As illustrated in FIG. 1, the present invention is a wireless receiver in which the reception frequency is set by a local oscillator controlled by phase-locked loop (hereinafter abbreviated as PLL), in which the reception and reception of radio waves of a specific frequency is performed. In this state, the operation of the PLL circuit is stopped and a fixed frequency oscillator for standby reception is used directly or multiplied instead, and when the PLL is operating, the frequency of the fixed frequency oscillator is divided and used as the reference frequency. This is a method for reducing power consumption during standby and reception.

Commonly used as a local oscillator in receivers
PLL circuit uses "mixer method" and "prescaler"
In the case of the above-mentioned patent application No. 90444 of 1982, it was a mixer method. The mixer method has a large degree of freedom in setting the oscillation frequency, so it is often used in general coverage receivers and the like, but it has the problem that complex spurious frequencies are likely to occur. The other prescaler method simply divides the loop frequency using a prescaler and only needs to take high frequencies into consideration.As prescaler ICs have advanced, high operating frequencies have become available at low prices, so step frequencies can be This prescaler method is the mainstream in FM receivers and the like.
As shown in Figure 2, the basic circuit 1 of the prescaler type PLL divides the oscillation frequency ₀ of a VCO (voltage controlled oscillator) 21 with a prescaler (frequency divider) 22, and then performs variable frequency division with a programmable frequency divider 23. do,
The phase comparator 24 compares the phase with the frequency _r of the reference oscillator 25, and the pulse output corresponding to the phase difference is sent to the VCO 2 as a control DC voltage through the LPF 26.
This configuration locks the oscillation frequency of 1. As a result, the oscillation frequency ₀ of VCO21 is the reference frequency _r
However, the frequency interval of communication channels is several 10 kHz to several 100 kHz, which is too low for a crystal oscillator, so in reality it oscillates at a high frequency _R , which is divided appropriately to obtain the required _r . I'm trying to get it.

The present invention focuses on the fact that the output ₀ of the PLL oscillation circuit is a multiple of _r , and divides the output frequency ₀ of the VCO 11 shown in FIG. Phase comparator 14
In the PLL oscillator circuit, which performs a phase comparison with the reference frequency _r and uses the pulse output corresponding to the phase difference as a control DC voltage through the LPF 46 to lock the oscillation frequency of the VCO 11, the operation of the PLL circuit 1 is stopped in the standby state. , instead, the output _R of the fixed frequency oscillator 15 exclusively for standby reception is used directly or multiplied by the multiplier 18, and the PLL
When the oscillator 15 operates, the frequency _R of the oscillator 15 is divided by the frequency divider 1.
The frequency is divided by 7 and used as the reference frequency _r . If the reference frequency _r is multiplied and used for standby reception, standby reception can be performed on any channel of all reception channels, but _R before frequency division is limited to a specific channel. However, since it is desirable that the number of stages of frequency division and multiplication be as small as possible, it is desirable to set _R that does not require frequency division for standby and reception of only a specific frequency.

[Embodiments of the invention]

Next, as a preferred embodiment of the present invention, application to a personal wireless communication device will be described.

Personal radio channel frequency is 903.0125
80 channels are set at 25kHz intervals between ~904.9875MHz, of which 903.0125MHz is the control channel and the other 79 channels are call channels, and calls are always made through the control channel.
Calls are automatically transferred to an empty channel among 79 channels. Therefore, the standby reception frequency′ ₀
needs to be only 903.0125MHz, and if the first intermediate frequency is set to 58.1125MHz considering spurious, the upper local oscillation frequency will be 961.125MHz, so if this is divided by 15, it will be 64.075MHz, and
Dividing the frequency by 2563 gives 25kHz, so in Figure 1, the oscillation frequency _R of the fixed oscillator 15 is set to 64.075MHz, and the multiplier 18 multiplies it by 15 to get ' ₀ = 961.125MHz.
By dividing 64.075MHz by 2563, the PLL reference frequency _r = 25kHz can be obtained.
As a result, the PLL oscillator output frequency ₀ can be obtained in 25kHz steps, so the programmable frequency divider 13
Depending on the settings, it is possible to receive channels at 25 kHz intervals, and when in standby mode, it is possible to switch to '_0' and receive control channels. Furthermore, ₀
The power consumption can be reduced by cutting off the power supply _VB of the PLL circuit 1 by means of the PLL power switch _S2 in conjunction with the switch _S1 (which may be an electronic switch circuit) that switches between the _two states.

〔Effect of the invention〕

As described in detail in the Summary of the Invention and Embodiments, this invention enables the above-mentioned audio circuit, In addition to stopping unnecessary circuits, the power supply current consumption (and therefore power supply power consumption) can be reduced to less than half of normal reception, and is particularly effective when applied to portable receivers that use dry batteries. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention and its embodiments, and FIG. 2 is a basic block diagram of a PLL circuit. 1 , 2 ...PLL circuit, 11, 21...VCO,
12, 22... Prescaler, 13, 23... Programmable frequency divider, 14, 24... Phase comparator, 15, 25... Fixed oscillator, 16, 26...
LPF, 17... Frequency divider, 18... Multiplier, S ₁ ,
S ₂ ...Switch.

Claims (1)

[Claims] 1. In a wireless receiver of the type in which the reception frequency is set by a local oscillator controlled by a phase-locked loop, when in the standby state of radio waves of a specific frequency, the operation of the phase-locked loop circuit is stopped, and instead, the operation of the phase-locked loop circuit is stopped, and instead Reducing power consumption during standby reception, characterized by using a fixed frequency oscillator directly or by multiplying it, and at the same time dividing the frequency of the fixed frequency oscillator and using it as a reference frequency during phase-locked loop operation. method.