JPH05191216A - Sweep range control system - Google Patents

Abstract

PURPOSE:To reduce the time till a synchronizing signal is again detected when an asynchronous detection state is reached from a synchronous detection state. CONSTITUTION:The system is provided with a frequency variable oscillator 1 outputting an oscillated frequency depending on an inputted frequency control signal, a demodulator 2 demodulating a reception intermediate frequency signal with an output from the frequency variable oscillator 1, a synchronizing signal detector 3 detecting the synchronizing signal in the reception signal from the demodulation output of the demodulator 2 to output a detection signal representing whether the state is in the detection state of the synchronizing signal or in the non-detection state, a sweep range controller 4 receiving a detection output of the synchronizing signal detector 3 and outputting the control information to change a sweep range in response to the time length of the non-detection state by using a point of time when the synchronizing signal detection state is transited to the non-detection state as a trigger, and a frequency controller 5 outputting a frequency control signal corresponding to the sweep range depending on the control information from the sweep range controller 4 to the frequency variable oscillator 1 to control the oscillating frequency of the frequency variable oscillator 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sweep range control method used to control a frequency sweep range for synchronizing with a reception intermediate frequency in a receiver of a radio communication device for receiving a continuous signal, and more particularly, to a sweep range control method. The present invention relates to a sweep range control method that controls a sweep range until reception synchronization is obtained again when a state in which reception synchronization is established can be lost.

[0002]

2. Description of the Related Art FIG. 3 shows a block diagram of a conventional sweep range control system. In this figure, this sweep range control system includes a frequency variable oscillator 11, a demodulator 12 that demodulates a reception intermediate frequency signal (reception IF signal) input from a terminal IN by an oscillation output from the frequency variable oscillator 11, and A sync signal detector 13 that detects a sync signal in the received signal from the output of the demodulator 12, and a frequency controller 15 that receives the detection output from the sync signal detector 13 and controls the oscillation frequency of the frequency variable oscillator 11. Is equipped with. In the conventional sweep range control system configured in this way, the sweep range of the receiving system is calculated by adding the maximum frequency deviations of all devices, such as the maximum frequency deviation of the transmitter and the maximum frequency deviation of the repeater, which are determined during system design. As a frequency controller 5
Always sweeps the entire sweep range.

[0003]

Since the conventional sweep range control system described above always sweeps the entire range, even if there is a momentary interruption such as switching from the active system to the standby system on the transmitting side, the receiving side does not operate. However, there is a problem in that the synchronization signal cannot be detected until the oscillation frequency of the variable frequency oscillator 11 reaches the original frequency after the sweep makes one round, and it takes time to resynchronize.

The present invention has been proposed in order to solve the problems of the prior art as described above, and until the sync signal is detected again when the sync signal detection state changes to the non-detection state. It is an object of the present invention to provide a sweep range control method that can shorten the time.

[0005]

In order to achieve this object, the present invention provides a method for performing frequency sweep for synchronizing with a received intermediate frequency signal in a receiver in wireless communication for transmitting a continuous signal including a synchronous signal. In the control method for controlling the sweep range, a variable frequency oscillator that outputs the oscillation frequency determined by the input frequency control signal, a demodulator that demodulates the received intermediate frequency signal by the output from this variable frequency oscillator, and A synchronization signal detector that detects the synchronization signal in the received signal from the demodulation output of the demodulator and outputs a detection signal indicating whether the synchronization signal is in the detection state or the non-detection state, and the synchronization signal detector To change the sweep range according to the time length of this non-detection state, triggered by the time when the detection state of the sync signal changes to the non-detection state in response to the detection output. A sweep range controller that outputs control information and a frequency control signal that outputs a frequency control signal corresponding to the sweep range determined by the control information from this sweep range controller to the variable frequency oscillator, and controls the oscillation frequency of this variable frequency oscillator. The sweep range controller is preferably configured to have a controller, and the sweep range controller is triggered by the time when the detection state of the synchronization signal is changed to the non-detection state, and the time length of the non-detection state is a synchronization detection state until a certain time. The control information for changing the sweep range is output so that only the vicinity of the frequency of time is set as the sweep range, and after a certain time elapses, the entire range is set as the sweep range.

[0006]

When the synchronizing signal detector detects the synchronizing signal from the output of the demodulator, the frequency controller performs the automatic frequency control (AFC) in the synchronizing state. The reason why the sync signal detector is in an asynchronous state where it cannot detect the sync signal may be because the frequency of the target reception intermediate frequency signal has changed.
It is necessary to perform the sweep operation by changing the oscillation frequency of the variable frequency oscillator. However, the cause of the change from the synchronous state to the asynchronous state is that the frequency of the target received intermediate frequency signal changes, and there is a momentary interruption of the continuous signal due to switching from the active system to the standby system on the transmission side, or temporary interruption. There may be cases where the received intermediate frequency signal is buried in noise due to heavy rain and large rain attenuation. In the latter case, the frequency of the received signal does not change significantly even in the asynchronous state, and it is sufficient to sweep only the vicinity of the received frequency in the synchronized state. In the sweep range control method according to the present invention, only the vicinity of the frequency of the received signal is swept until a certain time elapses from the synchronous state to the asynchronous state, and after the certain time elapses, the entire sweep range is swept. Since the control is performed, the synchronization signal can be detected again in a shorter time when the asynchronous state occurs for a short time due to a momentary interruption or the like.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the sweep range control system according to the present invention will be described in detail below with reference to the drawings. The block diagram of FIG. 1 shows the configuration of a control system based on this sweep range control method. In this figure, the demodulator 2 receives the output of the variable frequency oscillator 1 and demodulates the reception intermediate frequency signal (reception IF signal) which is a continuous reception signal. This demodulator 2
The sync signal detector 3 to which the output of 1 is supplied detects the sync signal from the received signal, and the detected output is supplied to the sweep range controller 4. The soup range controller 4 creates information for determining the sweep range by using this detection output as a trigger, and supplies this information to the frequency controller 5. The frequency controller 5 controls the oscillation frequency of the variable frequency oscillator 1 based on the input sweep range information.

The variable frequency oscillator 1 is composed of a voltage controlled oscillator (VCO) or the like, and can change the oscillation frequency in a range wider than the required total sweep frequency range. The demodulator 2 multiplies the received intermediate frequency signal input from the terminal IN by the oscillation output of the variable frequency oscillator 1,
A baseband continuous signal S1 is output through an internal low-pass filter (LPF). The continuous signal S1 has a frame structure as shown in FIG. 2, and one frame is composed of the synchronization signal Do and the data D1. The synchronization signal detector 3 detects the synchronization signal Do in the continuous signal S1, outputs the detection signal S2 indicating the synchronization state when the synchronization signal Do is detected, and outputs the detection signal S2 when the synchronization signal cannot be detected. The detection signal S2 indicating the asynchronous state is output.

In the sweep range controller 4, when the detection signal S2 from the sync signal detector 3 changes from the synchronous state to the asynchronous state, the internal timer is started at the timing of this change, and based on this timer output. Until a certain time elapses, control information S3 that commands a narrow band sweep that sweeps only the vicinity of the reception frequency in the synchronized state is output to the frequency controller 5, and after a certain time, a wide band sweep that sweeps the entire range is commanded. The information S3 is output to the frequency controller 5. As a result, the frequency controller 5 receives the control information S3 from the sweep range controller 4, outputs a frequency control signal corresponding to the sweep range determined by the control information S3 to the frequency variable oscillator 1, and the frequency variable oscillator 1 Control the oscillation frequency of.

With the sweep range control method that operates in this way, the sweep range can be controlled so as not to sweep the wasteful frequency range. Therefore, when the synchronous state is changed to the asynchronous state due to a momentary interruption or the like, the synchronous state is restored again. It is possible to shorten the time until.

The present invention is not limited to the above-described embodiments, but various modifications can be made within the scope of the invention.

[0012]

As described above, according to the present invention, a narrow sweep which sweeps the vicinity of the reception frequency in the synchronous state according to the duration of the asynchronous state from the time when the synchronous state changes to the asynchronous state as a starting point. Or a wide sweep that sweeps the entire range is switched, so when the transmitter side switches from the active system to the standby system due to a momentary interruption, etc. The advantage is that resynchronization can be achieved immediately. As a result, it is possible to always maintain a good communication state in a wireless communication system that transmits continuous signals.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a sweep range control method according to the present invention.

FIG. 2 is a diagram showing a frame structure of a continuous reception signal.

FIG. 3 is a block diagram showing a configuration of a conventional sweep method.

[Explanation of symbols]

 1 Frequency variable oscillator 2 Demodulator 3 Synchronization signal detector 4 Sweep range controller 5 Frequency controller

Claims (2)

[Claims] 1. A control method for controlling a sweep range when performing a frequency sweep for synchronizing with a received intermediate frequency signal in a receiver in a wireless communication for transmitting a continuous signal including a synchronization signal, which is input. A variable frequency oscillator that outputs the oscillation frequency determined by the frequency control signal, a demodulator that demodulates the received intermediate frequency signal by the output from this variable frequency oscillator, and a synchronization signal in the received signal that is detected from the demodulated output of this demodulator. The sync signal detector that outputs a detection signal indicating whether the sync signal is in the detection state or the non-detection state, and the detection output of the sync signal detector to change the sync signal detection state to the non-detection state. As a trigger at the time of transition to
The sweep range controller that outputs control information for changing the sweep range according to the time length of this non-detection state, and the frequency control signal corresponding to the sweep range determined by the control information from this sweep range controller A sweep range control method, comprising: a frequency controller that outputs to a frequency variable oscillator and controls an oscillation frequency of the frequency variable oscillator. 2. A control method for controlling a sweep range when performing a frequency sweep for synchronizing with a received intermediate frequency signal in a receiver in a wireless communication for transmitting a continuous signal including a synchronization signal, which is input. A variable frequency oscillator that outputs the oscillation frequency determined by the frequency control signal, a demodulator that demodulates the received intermediate frequency signal by the output from this variable frequency oscillator, and a synchronization signal in the received signal that is detected from the demodulated output of this demodulator. The sync signal detector that outputs a detection signal indicating whether the sync signal is in the detection state or the non-detection state, and the detection output of the sync signal detector to change the sync signal detection state to the non-detection state. As a trigger at the time of transition to
Outputs control information for changing the sweep range so that only the vicinity of the frequency in the synchronous detection state becomes the sweep range until a certain time, and the entire range becomes the sweep range until a certain time. And a frequency controller that outputs a frequency control signal corresponding to the sweep range determined by the control information from the sweep range controller to the variable frequency oscillator, and controls the oscillation frequency of this variable frequency oscillator. A sweep range control method characterized by having.