JPH0750612A - Synchronizer for receiver for spread spectrum communication - Google Patents

Abstract

PURPOSE:To easily hold synchronization by providing an envelope detector, a peak position detector and a peak position comparator and shifting the phase of sampling clocks in a direction for minimizing the difference of both compared in the comparator. CONSTITUTION:In a normal mode, a time window controller 32 is operated and detection is performed for spectrum inverse spreaded signals passed through a time window in the envelope detector 36. That is, since the time window is applied for the detection of a peak position in the peak position detector 37 as well, the influence of noise is hardly received. At the time, the difference between the output of the detector 37 and the center position of the time window (the storage value of a time window center position memory 40) is obtained in the peak position comparator 43 and the synchronization is held so as to minimize the difference. That is, the phase of the sampling clocks generated by an oscillator 41 and an m-frequency divider 42 is shifted by shift signals supplied from an up-down counter 44 and the synchronization of the time window is held.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for spread spectrum communication in which a time window is provided for a signal subjected to spectrum despreading and demodulation is performed using a signal which has passed through this time window. The present invention relates to a synchronization device for a spread spectrum communication receiver that holds data.

[0002]

2. Description of the Related Art FIG. 3 shows the configuration of a conventional spread spectrum communication receiver. In the figure, the passive correlator 31 is
Input the I and Q signals obtained by quadrature detection of the received signal,
The correlation value with the spread code is output. The time window controller 32 is
The output signal of the passive correlator 31 is input, and the signal passing through the time window is output. The differential detector 33 includes a time window controller 32.
The output signal of is input and delay detection is performed for each cycle of the spread code. The diversity combiner 34 inputs the detection output of the delay detector 33, performs diversity combining, and further, the decoder 3
5 decodes the output of the diversity combiner 34.

Further, the output signal of the passive correlator 31 is branched and input to the envelope detector 36, and the envelope is detected. The peak position detector 37 inputs the output signal of the envelope detector 36 and detects the maximum peak position within one cycle of the spread code. The changeover switch 38 sends the output signal of the peak position detector 37 to the averager 39 in the initial mode. The averaging device 39 averages the peak positions output from the peak position detector 37 over a plurality of cycles of the spread code, and stores them in the time window center position memory 40 as the first center position of the time window. The time window controller 32 sets the time window center position stored in the time window center position memory 40 as an initial value.

The oscillator 41 supplies a signal having a frequency m times (m is an integer of 2 or more) the chip frequency of the spread code to the m divider 42. The m-divider 42 generates a sampling clock by dividing the output signal of the oscillator 41 by m, and the passive correlator 31, the time window controller 32, the delay detector 33, the diversity combiner 34, the envelope detector 36, It is supplied to the peak position detector 37.

On the other hand, the changeover switch 38 sends the output signal of the peak position detector 37 to the peak position comparator 43 in the steady mode. The peak position comparator 43 compares the peak position output from the peak position detector 37 with the time window center position stored in the time window center position memory 40, and up / down counters the value according to the comparison result. 44. The up / down counter 44 adds the output value of the peak position comparator 43, and when the counter value exceeds a threshold value, sends a shift signal instructing the shift of the phase of the sampling clock to the m-frequency divider 42, and the counter Reset the value.

The synchronizer for maintaining the synchronization of the time windows in the time window controller 32 is an envelope detector 36, a peak position detector 37, a changeover switch 38, an averaging device 39,
The time window center position memory 40, the peak position comparator 43, and the up / down counter 44 are included.

As described above, the spread spectrum communication receiver has the initial mode and the steady mode, and each operates differently. That is, in the initial mode, since the time window controller 32 has no time window set, the control using the time window is not performed. At this time, the synchronizer detects the center position of the time window set as the initial value in the time window controller 32 by the envelope detector 36, the peak position detector 37, the averaging device 39, and the time window center position memory 40. , A time window is set in the time window controller 32.

In the steady mode, the time window controller 32
Operates and control using the time window is performed. At this time,
The synchronizer includes an envelope detector 36 and a peak position detector 3
7, time window center position memory 40, peak position comparator 4
3. With the up / down counter 44, the peak position (the output of the peak position detector 37) and the center position of the time window (the value stored in the time window center position memory 40) within one cycle of the spread code.
The synchronization is maintained by controlling so that the difference between the two becomes minimum.

That is, the peak position comparator 43 outputs "+1" when the peak position within one cycle of the spread code is larger than the center position of the time window, and outputs "-1" when it is smaller.
Is output, and the up / down counter 44 successively adds.
Here, when the counter value of the up / down counter 44 exceeds the threshold value, the shift signal for instructing the shift of the phase of the sampling clock is sent to the m-frequency divider 42, so that the phase of the sampling clock shifts. Windows are kept synchronized.

[0010]

In the conventional synchronizer for a spread spectrum communication receiver, the peak position detector 37 determines all envelope detection values within one cycle of the spread code in the steady mode. ing. Here, the input waveform of the peak position detector in the conventional configuration is shown in FIG. Thus, there is a noise component in one cycle of the spread code, so an error may occur between the value of the peak position detector 37 and the actual correlation peak position. Since this error becomes a comparison error in the peak position comparator 43 and a phase control error of the sampling clock in the m-frequency divider 42, it may be difficult to maintain synchronization.

An object of the present invention is to provide a synchronization device for a spread spectrum communication receiver which eliminates the above error factors and can easily maintain synchronization in a steady mode.

[0012]

According to a first aspect of the present invention, there is provided a synchronizing device for a spread spectrum communication receiver having a time window controller for providing a time window for a signal despread by a predetermined sampling clock. Then, in a spread spectrum communication receiver that demodulates using a signal that has passed this time window, an envelope detector that performs envelope detection on the signal that has passed the time window, and the output signal of the envelope detector. From the peak position detector that detects the maximum peak position within one cycle of the spread code, the center position of the time window initially set in the time window controller, and the peak position detected by the peak position detector. A peak position comparator for comparison and a sampling clock control means for shifting the phase of the sampling clock in the direction in which the difference between the peak position comparator and the peak position comparator are minimized are provided.

According to a second aspect of the present invention, there is provided a synchronizing device for a spread spectrum communication receiver, which comprises a first time window controller for providing a time window for a signal despread by a predetermined sampling clock. In a spread spectrum communication receiver that demodulates using a signal that has passed through a time window, an envelope detector that performs envelope detection on the signal that has been despread in the spectrum and an output signal of the envelope detector A second time window controller for providing a time window, a peak position detector for detecting a maximum peak position within one cycle of the spread code from a signal passing through the second time window controller, and a first time period The peak position comparator that compares the center position of the time window initially set in the window controller and the second time window controller with the peak position detected by the peak position detector was compared with the peak position comparator. And a sampling clock control means for the difference in person to shift the phase of the sampling clock in a direction to minimize.

[0014]

According to the first aspect of the present invention, in the steady mode, envelope detection is performed on the spectrum despread signal that has passed through the time window, and the peak position detector detects the correlation peak position from the envelope detection signal. Is characterized in that it detects The input waveform of the peak position detector in the present invention is shown in FIG. In this way, since the time window is also used to detect the correlation peak position, it is less affected by noise,
It is possible to easily hold synchronization.

In the second aspect of the invention, in the steady mode, a time window is provided for the envelope detection signal, and the peak position detector detects the correlation peak position from the envelope detection signal that has passed through the time window. It features a configuration. Also in the present invention, the input waveform of the peak position detector is as shown in FIG. In this way, since the time window is also used to detect the correlation peak position, it is difficult to be influenced by noise and it is possible to easily hold synchronization.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the invention described in claim 1. The same components as those in the conventional configuration shown in FIG. 3 are designated by the same reference numerals.

In the figure, the feature of this embodiment is that the signal input to the envelope detector 36 is a time window controller 3
It is configured to capture from the output of 2. Other configurations are the same as the conventional configuration shown in FIG. The passive correlator 31
Can be a matched filter or a convolver. The sampling clock control means according to claim 1 corresponds to the oscillator 41, the m-frequency divider 42, and the up / down counter 44 in this embodiment.

In the initial mode, the time window controller 32 does not control using the time window. Therefore, the signal input to the envelope detector 36 is the same both before and after the time window controller 32, and the time window center position initially set in the time window controller 32 is detected in the same manner as in the conventional case.

In the steady mode, the time window controller 32 operates to perform envelope detection on the spectrum despread signal that has passed through the time window. That is, since the time window is also applied to the detection of the peak position by the peak position detector 37, it is possible to reduce the influence of noise.

At this time, the synchronizer minimizes the difference between the peak position (output of the peak position detector 37) and the center position of the time window (stored value in the time window center position memory 40) within one cycle of the spread code. Control is performed to maintain synchronization. That is, the sampling clock generated by the oscillator 41 and the m-frequency divider 42 shifts the phase by the shift signal given from the up / down counter 44 to hold the time windows in synchronism.

FIG. 2 shows the configuration of an embodiment of the invention described in claim 2. The same components as those in the conventional configuration shown in FIG. 3 are designated by the same reference numerals. In the figure, the feature of this embodiment is that the time window controller 11 is arranged between the envelope detector 36 and the peak position detector 37, and the time window center position memory 4 is provided.
In the configuration, 0 sets the center position of the time window. Other configurations are the same as the conventional configuration shown in FIG. In addition,
A matched filter or a convolver can be used for the passive correlator 31. Further, the sampling clock control means according to claim 2 is the oscillator 41,
It corresponds to the m frequency divider 42 and the up / down counter 44.

In the initial mode, the time window controllers 32, 11
The control using the time window is not performed. Therefore, the configuration is the same as the conventional configuration without the time window controller 11, and the detection of the time window center position initially set in the time window controller 32 is performed in the same manner as in the conventional case. The time window center position detected here is also initialized in the time window controller 11.

In the steady mode, the time window controllers 32, 11
Operates, and a time window is provided for the output signal of the envelope detector 36, and the peak position detector 37 detects the correlation peak position from the envelope detection signal passing through the time window. That is, since the time window is also applied to the detection of the peak position by the peak position detector 37, it is possible to reduce the influence of noise. Note that the operation as the synchronizer is the same in this embodiment as well, and the sampling clock generated by the oscillator 41 and the m-frequency divider 42 is phase-shifted by the shift signal provided from the up / down counter 44 to generate a time window. To keep synchronization.

[0024]

As described above, according to the present invention, a signal passing through a time window is subjected to envelope detection, or a time window is provided to the signal subjected to envelope detection to detect the detected peak position as an actual correlation peak. Can be brought closer to the position. That is, the synchronization can be easily maintained even in the presence of noise.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the invention described in claim 1.

FIG. 2 is a block diagram showing the configuration of an embodiment of the invention described in claim 2.

FIG. 3 is a block diagram showing a configuration of a conventional spread spectrum communication receiver.

FIG. 4 is a diagram showing an input waveform of a peak position detector in a conventional configuration.

FIG. 5 is a diagram showing an input waveform of a peak position detector according to the present invention.

[Explanation of symbols]

 11 Time window controller 31 Passive correlator 32 Time window controller 33 Delay detector 34 Diversity combiner 35 Decoder 36 Envelope detector 37 Peak position detector 38 Changeover switch 39 Averager 40 Time window center position memory 41 Oscillator 42 m Frequency divider 43 Peak position comparator 44 Up-down counter

Claims (2)

[Claims] 1. A spread spectrum communication receiver having a time window controller for providing a time window for a signal subjected to spread spectrum despreading with a predetermined sampling clock, and performing demodulation using a signal passing through this time window. In the above, an envelope detector that performs envelope detection on a signal that has passed through the time window, and a peak position detection that detects a maximum peak position within one cycle of a spread code from an output signal of the envelope detector. And a peak position comparator that compares the center position of the time window initially set in the time window controller with the peak position detected by the peak position detector, and both compared by the peak position comparator. And a sampling clock control means for shifting the phase of the sampling clock in a direction in which the difference between Period equipment. 2. A spread spectrum communication having a first time window controller for providing a time window for a signal that has been spread-spread by a predetermined sampling clock, and performing demodulation using a signal that has passed through this time window. In the receiver, an envelope detector that performs envelope detection on the spectrum despread signal, a second time window controller that provides a time window for the output signal of the envelope detector, A peak position detector that detects a maximum peak position within one cycle of a spread code from a signal that has passed through the second time window controller; the first time window controller and the second time window control The center position of the time window initially set in the detector and the peak position comparator that compares the peak position detected by the peak position detector, and the direction in which the difference between the two when compared by the peak position comparator is minimized. Synchronizer of the spread spectrum communication receiver, characterized in that a sampling clock control means for shift a phase of the sampling clock.