JPS61274439A - Resetting system for eliminating device of cross polarized wave interference - Google Patents

Abstract

PURPOSE:To eliminate an interruption in a transmission by providing and constituting the first means which detects the carrier step out of the first demodulator, the second means which detects the abnormality of a code error rate at the first polarized wave side and the third means which sets the output of a variable coupler at a prescribed value set in advance by the outputs of the first and the second means. CONSTITUTION:The first means 5 which detects the carrier step out of the first demodulator 2 and the second means 6 which detects the abnormality of the code error rate at the first polarized wave side and the third means 7 and 4 which set the output of a variable coupler 1' at the prescribed value set in advance by the outputs of the first and the second means 5 and 6. For example, a step out detector 5 sets step out signals 107 and 107' as '0' when digital demodulators 2 and 2' are carrier-synchronized and sets them as '1' when a carrier is out of step. A code error detector 6 detects the error of a code already known that is transmitted periodically from a transmission side from an output signal 105 and when the code error rate is normal, it sets a code error signal 108 as '0' and sets it as '1' when it is deteriorated abnormally over a regulated value. A reset signal generator 7 generates a reset signal 109 from the step out signals 107 and 107' and the code error signal 108.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reset method for a cross-polarization interference removal device.
In particular, the present invention relates to a reset method for a cross-polarization interference canceling device used in a digital wireless communication system that uses two orthogonal polarized waves.

[Conventional technology]

In wireless communication systems, two orthogonal polarized waves (vertical and horizontal, or left-handed and right-handed circularly polarized waves) of the same frequency are sometimes used in order to utilize frequencies effectively. Orthogonal polarized waves generate cross-polarized waves due to anisotropy of the medium quality due to rain, etc., and cross-polarized waves interference occurs between the two polarized waves. As a crossed single-wave interference canceling device suitable for digital wireless communications, it controls a transversal filter based on the information of the demodulated baseband signals of both the main polarization receiving interference and the different polarization giving. Devices for removing chemical polarization have been proposed (for example, Japanese Patent Laid-Open Nos. 55-133156 and 59-77734). In such equipment, if an abnormality occurs in the demodulated output due to an extreme drop in the level of the different polarized waves due to fading or an increase in noise, the cross-polarization interference canceling device will not operate normally. Otherwise, interference will be injected into the main polarized wave, so it is necessary to reset it at this time. JP-A-59-77734 discloses that a cross-polarization interference canceling device is reset when carrier synchronization loss of a demodulator on a different polarization side is detected or when the code error rate on a different polarization side is abnormally degraded. A method has been proposed. However, in the previous method, since the reset is performed after detecting the loss of synchronization, interference is injected into the main polarization immediately before the reset, and there is a possibility that the main polarization demodulator may also become out of carrier synchronization at this time.

In the latter method, although the cross-polarization demodulator synchronizes with the carrier and has the effect of an eight-cross polarization interference canceling device, it may remain reset.

As explained above, with the reset method of the conventional cross-polarization interference cancellation device, the carrier synchronization of the main polarization side demodulator is lost just before resetting, or the reset remains in place even though there is a cancellation effect. The disadvantage is that there is a risk.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention, or in other words, the purpose of the present invention is to solve the above-mentioned drawbacks and prevent the carrier synchronization of the main polarization side demodulator from being lost at the time of reset (in addition, the carrier wave synchronization of the main polarization side demodulator will not be lost). An object of the present invention is to provide a reset method for a cross-polarization interference canceling device that does not perform resetting to the maximum extent possible while carrier synchronization is achieved.

[Means for solving problems]

The reset method of the cross-polarized interference canceling device of the present invention includes digitally modulating the first polarized wave and digitally modulating the first received signal with the second polarized wave orthogonal to the first polarized wave. a variable coupler that can couple the signal received by the receiver and control the coupler by a control signal, and a first demodulator that demodulates the first received signal and outputs a first baseband signal. a second demodulator that demodulates the second received signal to which the first received signal is combined by the variable coupler and outputs a second baseband signal; a control signal generator that generates the control signal based on a baseband signal, and a cross-polarization interference that removes interference caused by the first polarization leaking into the second polarization. In the reset method of the removal device, a first means for detecting carrier synchronization loss of the first demodulator, a second means for detecting an abnormality in the bit error rate on the side of the first polarization;
and third means for setting the output of the variable coupler to a predetermined value based on the outputs of the first and second means.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments.

FIG. 1 is a block diagram showing an embodiment of a reset method of a cross-polarization interference canceling apparatus according to the present invention.

The embodiment shown in FIG.
and the control signal 102 or 102 are input, and the combined signal 10
3 or 103', and the received signal 101 or 101' and the combined signal 103 or 1.
03 and baseband signal 104 or 104'
Digital demodulators 2 and 2' that output
' and a control signal generator 3 which outputs a correction signal 106, 106', and a reset circuit 4 which receives a correction signal 106 or 106' and a reset signal °1o9 or 109' and outputs a control signal 102 or 102'. 4' and an out-of-sync signal 10 connected to the digital demodulator 2 or 2'.
Out-of-synchronization detectors 5 and 5' output signals 7 or 107', and code error detectors 6 and 6 input the output signal 105 or 105' and output a code error signal 108 or 108'.
', the out-of-synchronization signals 107, 107', and the code error signal 108 or 108' are input to the reset signal generators 7, 7', which output the reset signal 109 or 109'.
It is composed of:

The received signals 101-101 are signals obtained by frequency-converting two mutually orthogonal polarized waves into an intermediate frequency band.

The embodiment shown in FIG. 1 removes cross-polarization interference caused by polarization of the received signal 101 leaking into the polarization of the received signal 101', and removes cross-polarization interference in the opposite direction. Since these two movements are symmetrical to each other, only the previous tightening movement will be explained below.

A variable coupler 1 consisting of an intermediate frequency band transversal filter is controlled by a control signal 102 and receives a received signal 101.
A combined signal 103' is generated from.

The combined signal 103' is combined with the received signal 101' and input to the digital demodulator 2'. The digital demodulator 2' regenerates the carrier wave in phase synchronization with the carrier wave component of the input signal,
The input signal is synchronously detected using this carrier wave and a baseband signal 104' is output. Digital demodulator 2 similarly outputs baseband signal 104. The control signal generator 3 is
The baseband signals 104 and 104' are identified and transmitted, and the transmitted output signals 105 and 105' are outputted, and the difference between the baseband signal 104' or 104 and the output Kimigo 105' or 105 is determined. The correlation between the generated error signal and the baseband signal 104 or 104' is determined, and the control signals 102 and 102' are output as modified signals 106 and 106' that are successively modified. The reset circuit 4 integrates the correction signal 106 to generate the control signal 102, and sets the control signal 102 to a predetermined initial value when the reset signal 109 is "0" (reset). The combined signal 103' controlled by the control signal 102 cancels the cross-polarization interference received by the received signal 101' except when reset, and when reset, the combined signal 103' is controlled by the control signal 102.
02 stops the variable coupler 1' from outputting the combined signal 103'. The above-mentioned operations performed by the control signal generator 3, reset circuit 4, and variable coupler 1' are not directly related to the present invention, so further explanation will be omitted, but details thereof can be found in JP-A-59-77734. is explained.

Next, the operation of generating the reset signal 109 will be explained.

The out-of-sync detectors 5 and 5' are connected to the digital demodulators 2 and 2'.
If the carrier is synchronized, out-of-synchronization signals 107 and 107'
It has a function to set the signal to 10'' and to set it to 1 when carrier synchronization is lost, and the circuits described in Japanese Patent Publication No. 55-34619 can be used for this purpose. The code error detector 6 is
Errors in known codes that are sent periodically are detected from the output signal 105, and if the code error rate is normal, the code error signal 108 is set to "0", and if it exceeds a certain value and deteriorates abnormally, the code error signal 108 is set to "0". 11''.The reset signal generator 7 generates out-of-synchronization signals 107 and 107' and a code error signal 10.
8 generates a reset signal 109.

FIG. 2 is a block diagram showing details of the reset signal generating section 7. As shown in FIG.

The reset signal generator shown in FIG.
A monostable multivibrator (hereinafter abbreviated as monostable multi) 71 which inputs signal 8 and outputs signal 701, and signal 70
10 inverted signal, inverted up, out-of-synchronization signal 107 is input, signal 7
Input ND circuit 72 that outputs 02 and signals 701-702
an OR circuit 73 which inputs the signal 703 and outputs the signal 703;
03 and a NOR circuit 74 which inputs the out-of-synchronization signal 107' and outputs the reset signal 109.

When the level of the received signal 1010 decreases to the extent that the carrier synchronization of the digital demodulator 2 is lost due to a level fluctuation within a certain width, such as fading, the bit error rate of the output signal 105 decreases before the carrier synchronization is lost. First, the code error signal 108 deteriorates abnormally.
Changes from "to 11". The monostable multi 71 normally keeps the output at "O" and changes the output to 11' for a certain period of time from the time when the input power rises from 0 to 11', so the code error signal 108 becomes @1'. The signal 701 is set to ``1'' for a certain period of time from the time when the reset signal 109 is set to ``1'' during this period. The time during which the monostable multi 71 remains at 11" is selected to be longer than the time from when the code error detector 6 detects an abnormality in the code error rate until the carrier synchronization of the digital demodulator 2 is lost. The signal 701 becomes 11 m at the time when the carrier synchronization is lost and the out-of-synchronization signal 107 becomes 1''. While the signal 701 is 11", the out-of-synchronization signal 107 is blocked by the human ND circuit 72, and when the out-of-synchronization signal 107 is "1" at the time when the signal 701 returns to "O", the signal 702 becomes 11". '', and the reset signal 109 continues to be in the state of ``0''. In this way, the received signal 101 due to fading etc.
When the carrier synchronization of the digital demodulator 2 is lost due to a drop in the 0 level, the reset signal 109 becomes 10'' immediately before that, and the variable coupler 1 is reset.

In the conventional reset method in which the reset signal 109 is generated only from the out-of-synchronization signal 107, the variable coupler 1' is reset after the carrier synchronization of the digital demodulator 2 is lost. Variable coupler 1
The variable coupler 1' continues to output the combined signal 103 until ' is reset. During this time, baseband signal 10
4 does not include the baseband signal information transmitted by the polarization on the side of the received signal 101, and therefore the modified signal 106 becomes unstable and fluctuates due to meaningless disturbances.
The combined signal 103', which is the output of
There is a possibility that the carrier synchronization of the received signal 101' is lost and the transmission of the received signal 101' is interrupted.

In the embodiment shown in FIG. 1, the variable coupler 1' is reset and the output of the combined signal 103' is stopped before the carrier synchronization of the digital demodulator 2 is lost and the corrected signal 106 becomes unstable. There is no fear that the carrier synchronization of the digital demodulator 2' will also be lost due to the carrier synchronization of the demodulator 2 being lost.

When the fading is recovered and the level of the received signal 1010 rises, first the carrier synchronization of the digital demodulator 2 is recovered and the out-of-synchronization signal 107 changes from 11"m to @O", and after a while the bit error rate of the output signal 105 decreases. It becomes normal and the code error signal 108 changes from @1'' to @O''. During this time, the signal 701 remains at °0'', so the out-of-sync signal 10
As soon as 7 becomes ``0'', the reset signal 109 becomes @0.
" changes from "1" to "1", the reset of the variable coupler 1' is released, and the cross-polarization interference removal effect by the combined signal 10B is restored (however, the digital demodulator 2' synchronizes with the carrier and loses synchronization with the signal 107'). (if the height is 0”). In this way, in the embodiment shown in FIG.
Since the cross-polarization interference removal effect by the combined signal 103' is recovered immediately without waiting for the bit error rate of 05 to recover normally, this is more effective than the conventional reset method in which the reset signal 109 is generated only from the bit error signal 108. The cross-polarization interference removal effect recovers quickly.

Also, the received signal 1010 level decreases, and the output signal 1
If the code error rate of 05 becomes abnormal but the carrier synchronization of the digital demodulator 2 remains at a level that does not lose the carrier synchronization, the code error signal 108 changes from ``O'' to @1, but the out-of-synchronization signal 107 changes to @0''. Therefore, the signal 701 which is the output of the monostable multi 71 changes from @0'' to @12 and the variable coupler 1' is reset once, but the signal 701 returns to 10'' after a certain period of time, so at this time The reset of the variable coupling 1 is released and the cross-polarization interference removal effect is restored.

In this way, the embodiment shown in FIG.
is carrier-synchronized and a cross-polarization interference cancellation effect can be expected, the bit error rate of the output signal 105 becomes abnormal and even if the variable coupler 1' is reset once, this reset is canceled after a certain period of time and the cross-polarization interference cancellation effect is expected. Since the polarization removal effect is recovered, the code error rate of the output signal 105 is abnormal even though the cross-polarization interference removal effect can be expected as in the conventional reset method in which the reset signal 109 is generated only from the code error signal 10B. There is no need to keep resetting the variable coupler 1' for a certain period of time.

When the digital demodulator 2' is out of carrier synchronization, the out-of-synchronization detector 5' sets the out-of-synchronization signal 107' to @1". At this time, the NOR circuit 74 of the reset signal generator 7 changes the reset signal 109 to @O ', the variable coupler 1 is reset and the combined signal 103' is not outputted.As a result of this reset, when the carrier synchronization of the digital demodulator 2' is restored, the combined signal 103' becomes unstable and this causes interference. This avoids the situation of delaying the recovery of carrier synchronization.However, since this effect is not a direct objective of the present invention, the out-of-synchronization signal 107' is replaced by the reset signal 109.
It is not an essential requirement of this Prophecy that it be used to generate When the out-of-synchronization signal 107' is not used, the NOR circuit 74 of the reset signal generating section 7 is unnecessary, and the inverted signal of the signal 703 may be used as the reset signal 109.

〔Effect of the invention〕

As explained in detail above, the reset method of the cross-polarization interference canceling device of the present invention prevents the loss of carrier synchronization of the demodulator on the polarization side that causes cross-polarization interference and the bit error rate of the output signal on this side. Since this method detects abnormalities and resets the variable coupler using these detection outputs, the variable coupler can be reset before the carrier synchronization of the demodulator on the polarization side that causes cross-polarization interference due to fading etc. is lost. This loss of carrier synchronization has the effect that the carrier synchronization of the demodulator on the polarization side that eliminates cross-polarization interference will not be interrupted, and transmission will not be interrupted. Since the reset of the variable coupler is released immediately when the carrier synchronization of the demodulator is recovered, the cross-polarization cancellation effect is quickly recovered, and even though the cross-polarization interference cancellation effect can be expected, This has the advantage that the variable coupler does not need to be reset continuously while the bit error rate of the output signal on the polarization side that causes polarization interference is abnormal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the reset method of the cross-polarization interference canceling apparatus of the present invention, and FIG. 2 is a block diagram showing details of the reset signal generating section 7 in FIG. 1. 5... Out-of-synchronization detector, 6... Code error detector, 7... Reset signal generator. Agent: Susumu Uchihara, patent attorney 1.・105・1
05': Figure 1

Claims (2)

[Claims] (1) A first reception signal that is digitally modulated with a first polarization is coupled to a second reception signal that is digitally modulated with a second polarization that is orthogonal to the first polarization, and the amount of coupling is calculated. The first received signal is combined by a variable coupler that can be controlled by a control signal, a first demodulator that demodulates the first received signal and outputs a first baseband signal, and the variable coupler. a second demodulator that demodulates the second received signal and outputs a second baseband signal; and a control signal that generates the control signal based on the first and second baseband signals. In a reset method of a cross-polarization interference canceling device that removes interference caused by the first polarized wave leaking into the second polarized wave, the reset method includes: detecting carrier synchronization loss of the first demodulator; a first means, a second means for detecting an abnormality in the code error rate on the side of the first polarization, and an output of the variable coupler is predetermined based on the outputs of the first and second means. and third means for setting the value to a value. (2) The third means includes a fourth means for outputting a predetermined time signal from the time when the second means detects the abnormality, and a logic between the output thereof and the output of the first means. A reset method for a cross-polarization interference canceling device according to claim 1, further comprising a fifth means for outputting the sum.