JPS5967743A - Circuit eliminating cross polarized wave interference - Google Patents

Abstract

PURPOSE:To eliminate the cross polarized wave interference even if waveform distortion is large, by providing a delay circuit connected at least to an output of the 1st and the 2nd transversal filters, the 3rd transversal filter generating a compensating signal cancelling an interference signal, a signal synthesis circuit and a control signal generating circuit. CONSTITUTION:Delay circuits 8, 9 are inserted between an output of the transversal filters 1, 2 and that of signal synthesizing circuits 5, 6, and give the same delay of the 3rd transversal filters 3, 4. The filters 3, 4 are connected from being branched at the output of the filters 1, 2 and time matching is attained with delay circuits 8 and 9. Thus, the cross polarized wave interference is rejected stably, by eliminating the waveform distortion of the input of the cross polarized wave interference rejecting filters 3, 4, i.e., by branching the filters 3, 4 from the output of the filters 1, 2 equalizing the waveform distortion. Further, outputs 701, 702 of a control signal generating circuit 7 are regenerated base band signals of V and H.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a cross-polarization interference removal circuit, particularly a digital variable f
I was made r! ! Receives signals of two intersecting polarizations. In BAT (A), the orthogonal polarization communication method that effectively uses frequencies by using two polarized waves (vertical and horizontal or left-handed and right-handed circularly polarized waves) of the same frequency is attracting attention. The polarization of this J2 is 1~
Due to the anisotropy of the 1 peak, a difference 11i1i wave is also generated, and +# is fully excited between both polar channels. Therefore °C, intersection intersection J
In addition to improving the polarization characteristics of antennas and power supply devices, the transmission method has been improved to 4:1. Polarization on radio wave propagation due to +4 etc.! Difference polarization to compensate for the deterioration of h-characteristics-1
'The 1ji-1 shot of the interference removal circuit is also an M<%' 4-problem.

Since Tjr, microwave + Ii digital camera N Ni 3
The cross-polarization interference removal circuit in 1) is disclosed in Japanese Patent Application Laid-open No. 55
As proposed in Publication No. 133156, the trans-purple filter is controlled based on the demodulated baseband signal information to eliminate cross (IIIi) interference.However, in this method, tI: J:
As described later, the cross-polarized interference sound 1'J cancels out, 't.
(The s signal is directly branched from the output of each 17M receiver and generated by a transverse filter connected to C. If the waveform distortion due to fading etc. is large, it is crossed (
ii! The drawback is that it cannot sufficiently remove U-shiwata.

The purpose of the present invention is to eliminate the above-mentioned drawbacks in a cross-polarization interference cancellation circuit for digital communication using a transver- lar filter (~, a method that can eliminate cross-polarization interference even when waveform distortion is large). An object of the present invention is to provide a ν polarization interference cancellation circuit.

The cross-polarization interference removal circuit of the present invention is described in Section 11 of Ki 1. A first transversal filter that receives the i-wave reception output and applies waveform equalization, and a second transversal filter that receives the M output and applies waveform equalization. , at least one delay circuit connected to the output of at least one of the first and second transversal filters and providing a constant delay time; at least one third transbar that is branched and connected and generates a compensation signal H that cancels the interference signal 11 of the first or second polarized wave impregnated in the received output of the second or first polarized wave; a transversal filter, at least one synthesis circuit for synthesizing the output of the delay circuit and the output of the third transversal filter;
The outputs of the first and second transversal filters operated by the circuit are received by the circuit boards and open sides of the first, second and third transversal filters. C1I# is achieved by providing a control i:i generation circuit that generates a control signal.

The present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a conventional example of a cross-polarization interference removal circuit using a transverse filter.

In FIG. 1, a transparence filter 1 receives a demodulated V-polarized wave 101 and performs waveform equalization.

Similarly, the transversal filter 2 receives the demodulated H polarized wave 102 and performs waveform equalization. The transversal filter 3 branches the (1) polarized wave 101 and generates a compensation signal 103 that cancels out the interference signal of the V polarized wave impregnated in the H polarized wave 102. Similarly, the transversal filter 4 splits the l-polarized wave 102 and generates a compensation signal 104 that cancels the interference signal of the H-polarized wave included in the V-polarized wave. A signal synthesis circuit 5 synthesizes the outputs of the transversal filters 1 and 4, and a signal synthesis circuit 6 synthesizes the outputs of the transversal filters 2 and 3. Transversal filters 1 and 2 receive the outputs of control 1^ issue generation circuit 7 and signal synthesis circuits 5 and 6.
．． Control signals 710 and 720 controlling 3 and 4 respectively.
．． 730 and 740 are generated.

The operation of this cross-polarization interference cancellation circuit is an extension of an adaptive waveform equalizer using a known transversal filter.
Each of the transversal filters 3 for removing cross-polarization interference of 14 polarized waves = r variable xr - circuit 3],
32.33.34 and 35 are the difference between the demodulated Base Pantoy No. 8 of the H polarization and its estimated value, and the error signal of the V polarization that causes interference. fr
- It is controlled to find the correlation with the baseband signal and generate a compensation signal that cancels out the signal difference polarizer 71' (c of 11 polarizations. Reception output 10 of V polarization and H polarization
1 and 102 as ``+01 and)-1, o2, i is 0.±1.±2... and VIOI −-VO+ Σ ”i”i +Σ *H
V4 ・=-=(1) 1±O II+oz = If. −1−,4゜riHi+Σδi
vi ”'”' (2). Here, V, , , IIofYZ (Ft ?? is the reception signal of each polarization equal to No. 1, and the second term &=1. Leading (+ < 0 ) and trailing detention (i > O)
The third term is the interference component from the synchronization code (i=o) of the intersection (f'+ wave component), the preceding device and the subsequent code.The human power signal 105 of the control issue generation circuit 7
+ 1.06 is the name - Waveform distortion and cross-polarization interference are reduced by the action of the transversal filter, but it can be displayed in the same format as vtos ``VO + Σα'fvi + Σβi Hi
...(3) Hloa =Ho+Σγ'1Hi-1
It is expressed as 4δ-Vi − (4) 1Φ0. When the control signal generation circuit 7 determines that 1 (estimated polarization value Hk) IO has been correctly determined, the error signal I is obtained from equation (4) as E=Σγ/1l−1i+Σδ/, Vi
...15), and when we calculate the correlation between this and V 105 in equation (3), we find that V polarization and l (polarization have completely uncorrelated data being transmitted, and each data series also has 11 Since it is sequentially uncorrelated, if we ignore the higher-order minute terms, we get (5
) Only δ'OVO in the second term of the equation can be detected. In order to reduce this value, the variable M1 interest of the intermediate tap of the transformer 9 filter 3 is controlled by the circuit 3, and the synchronization code component of the cross-polarization interference of the 11 polarized reception output of equation (2) is controlled. Sode Yui No. 8 δ erases δ OVO. vo is obtained. That is, δ0−δo”δ1o10 1.(
6) The compensation coefficient δ0 is controlled to be as follows. Similarly, for the interference components from the preceding code and the following code, (
3) A signal obtained by shifting v tos in the equation by 1 bit and (5
) By determining the correlation with the error signal of the equation, each compensation signal δ1vi(i';0) is obtained.

The transversal filter 4 that removes cross-polarization interference of V-polarized waves is similarly controlled.

In the circuit shown in FIG. 1, the transversal filter 3d and the reception output 101 are branched and connected, so the compensation signal of the intermediate tap of the transversal filter is calculated from equation (1) as δOVIOL ””δ□o Vo ＋δo (Σ” iv
i+Σβi'i)-1-0...(7) It is expressed as follows. Variable weighting of the leading and trailing taps of the transversal filter is also provided by circuits 31, 32 and 34.
Each compensation point controlled by 35 is vl. Signal ■, which is 1 with i bits. 1 (g) by setting each compensation coefficient ii.・・・・・・
・(8) In both cases, when the waveform φ is small, cross polarization compensation 1
The A component is only the first term, and the synchronization, preceding, and subsequent valley interference components are independently controlled, and good compensation is performed with A'Abi.However, when waveform distortion becomes large, each interference component must be controlled. Since the loops influence each other, convergence becomes slow and the loop becomes unstable, the removal of opposite polarization interference becomes insufficient, and there is also a disadvantage that instability causes F1 error. .

One way to eliminate the above drawback is to eliminate the waveform distortion of the inputs of the transversal filters 3 and 4 for removing cross-polarization interference, as is clear from the detailed explanation. The transformer filters 3 and 4 are branched from the output side of the transformer filters 1 and 2 for equalizing waveform distortion. With this kind of connection, cross-polarization interference can be stably removed even when waveform distortion is large.
This has the effect of suppressing the occurrence of No. 71 error.

FIG. 2 is a block diagram of the first embodiment of the present invention, and has the same transversal structure as FIG. 1.

2.3 and 4, the signal synthesis circuits 5 and 6, the control signal generation circuit 7, and the third transversal filter 3 inserted between the outputs of the transversal filters 1 and 2 and the signal synthesis circuits 5 and 6. and delay circuits 8 and 9 that give the same slow crawling time as 4, and the main difference from FIG. Is the connection broken and the time alignment performed by delay circuits 8 and 9? ]
Because of this, C1 can be crossed without being influenced by waveform distortion. e (JI+J-wave interference IIl
′+ leaving is present. Note that the outputs of the control signal generation circuit 7 are baseband signals 701 and 702 obtained by multiplying V and H by (1).

Figure 31. Using a transversal filter in the intermediate frequency band /ξ In the block diagram of the second example of the present invention, V
(I + ii wave O, 1: (j l l (lit wave (7J out of 11J) JrtJ wave reception, 1 connected to outputs 111 and 112, and transversal filters 11 and 12 in the 7°C intermediate frequency band, FIG. Intermediate frequency band transversal filter 13 introduced in the same manner as
l 4, delay circuit 18.19, signal synthesis circuit 15.16
2, the turning control No. 8 generation circuit 7, the signal synthesis circuit 15, 16, and the control I No. 1 generation circuit 17, 17' inserted between the signal synthesis circuit 15, 16 and the control No. 1 generation circuit 7. It is °C. ? According to an old report from a baseband expert, the technique of controlling a transversal filter in the intermediate frequency band to perform waveform equalization is based on the fact that the carrier frequency of the input modulated signal, that is, the intermediate frequency (f It is thought that this is limited to cases where N is an integer multiple of 1l-7 of the variable frequency (f8) of the signal, and is always 1. Also f. = N f5 (N is a positive integer) It was not used in general microwave band wireless communication where it is not possible to select an intermediate frequency. however,%
f in Japanese Patent No. 56-215271. ”, a method that can be applied to the case of 6Nf8 was proposed, and with this technology, a cross-polarization interference removal circuit using a transversal filter at the C1 intermediate frequency (;) can also be used for general use. , the circuit of this embodiment has the same effect as that shown in FIG. 2.

FIG. 4 is a block diagram of the third embodiment of the present invention.
) This is an example using a Haasband transversal filter. Transversal filters 21 and 22
receives the baseband signals of two lines of in-phase and 1-cross, respectively, performs wave pre-9fL and 1-signal interference sleeve Ilk, and passes the in-phase and j0 father outputs; 2
9.29' and transversal filter 23.23'
, 24. Send at 24'. The transversal filter is configured to generate two sets of compensation signals that are separately controlled by two control signals, and the outputs thereof are passed through a signal synthesis circuit 2 with orthogonal and four-phase outputs of opposite polarization, respectively.
5.25', 26°26'. The control signal generation circuit 27 generates in-phase/varus signals 105 and 10 of each polarized wave.
5', 106.

106' and each error signal to generate respective control signals. Transversal filter 2], 22 jti control (N4271.

272 contains the in-phase and il'1 father waveform distortions and the 41t and II fli control signals for eliminating intersymbol interference, respectively. With the above configuration, the differential polarization interference between the two polarized waves each subjected to uncle modulation can be removed even when the 77U distortion is large.

FIG. 5(a) id: A block diagram of an embodiment of the transversal filters 23, 23', 24, 24' in FIG. 4 delay circuits 4o, and two sets of variable circuits (single-digit circuits 41 to f5 and 41' to 45') that are branched from before and after each delay circuit 40 and controlled by 11 separate control signals. A 5-tap transformer consisting of two force generators 46 and 46' generating two sets of compensation force numbers 401 and 4 (12), each variable This is a versatile filter.This is a set of delay circuits that performs the functions of 302 transversal filters shown in Figure 1, and 23 and 23 in Figure 4.
', 24, 24' can each be replaced with two transversal filters Z). Conversely, among the two outputs of the transverse filters 23 and 23' (24 and 24'), the same signal combining circuit 26 or 2
The signals supplied to 6' (25 or 25') are synthesized in advance, and this synthesis circuit and the transversal filter 23123'Th shown in FIG. It has 4 inputs and outputs.
The group! It can also be configured as one transversal filter that receives the fi control signal.

FIG. 5(b) is a block diagram of an embodiment of an intermediate frequency band Lancer filter used in the case of f-autonomous modulation. delay 11j [route 50. 101 paths 51 to 55 and 51' to 55', Kason device 56.56', and adder 56
900) which combines the output of ゜56' with a phase difference of 90'
The interference between the two components can be easily removed with a set of incoming forces. Therefore, 161 intersections? Whether processing JAl at f-.1tj-J or baseband processing, it is possible to deal with the problem using almost the same circuit configuration as shown in FIG. /r (-1, jj in Figure 3
< l, demodulators 17 and 1.7' each generate a baseband output of the iM father two rows and a demodulator for cross-sectional modulation.
In R class::-7, it is necessary to change the sentence control signal generation circuit 1 to the control signal generation circuit 27 shown in FIG. 4, which inputs 4 demodulated outputs.

A configuration in which one of the circuits 5:+ and s3' is omitted can also be used as shown in FIG. 5 (1).
Corresponding to this, 12'Cilt control (can be used by changing the entire M number generation circuit.The explanation so far has been about four delay circuits/f: there is no need) - wasteful transversal fi/
It goes without saying that transversal filters with taps other than 5 taps can be used in the present invention.

In the above explanation, as is clear from Figures 1 to 4, the control No. 6 generation circuit applies interference on the output side of the transversal filter and receives interference from the demodulated baseband signal on the output side of the transversal filter. The ZF (zero-7 orsing) method equalization algorithm is used, which generates a control signal by calculating the correlation between the error signals on the side where the Both the I and 1 methods are known as the signal and error on the input side of the lance bar seal filter (correlation with the M-number):
It is also possible to apply the 1y method (root mean square equalization method) algorithm. Actual circuit V
Is it a signal? +- Digitalization L compared to a certain threshold candy
'A simplified algorithm with C1lit control is used. In the above 7't method, °C is also 1b1'' Gogogo is generated - to be sure, the demodulated baseband signal of both GII waves is essential, but it does not cause interference. Demodulation No. 18 on the side 1) Fl using a perturbation signal that does not require ζ information
j! A method for controlling f was devised in 1986-055530, and it is also possible to apply this control force 2 to the present invention. 14i
This is a block diagram of a real Mu example of the l control Ii-i generation circuit, and the in-phase ridge of the polarized wave whose interference is to be removed is t:
The difference detector 60 which generates an error signal from the demodulated Isho signal of the output of '-, 1l-l cross, and iJ' change f4''+mi is 11 tat to the fli control function of the circuit. An oscillator 71 generates a perturbation signal, a correlator 72 calculates the correlation between the error signal and the perturbation signal.
an integrator 73 that inverts the output of the integrator 73 and sends out a 7-point control signal. A filter 75 for superimposing the control signal and the perturbation signal;
'In average value? Attenuator 77 (attenuator 77)
It consists of a controller 70 and a transversal filter;
ili control controller 70.70rJ7011.70C
, 70(l) so that the frequencies of the j1 signals intersect with each other by 161, for example:, ωo, 2ωn+3ω0...
・Selected as In this method, interference is removed by determining the perturbation frequency component of the error signal using a positive/zero correlator 72, determining the direction in which the control signal is to be changed, and performing C control through a divider 13 and an inverter 74. The details of Ijj i'-1, (,!lj are '1.
' + Application No. 5.6-055530, so please refer to it if necessary.

I"!I bj8 tfj,
It is possible to receive both polarized signals on the i4 side. However, with the satellite communication method, Qj
, not necessarily one Jl! j, It is expected that both polarizations will not be used when disembarking, and only the bIi wave will be used at night. The interference signal that occurs can be complemented (there is no need to do R-=, and the circuit where -i<14 is omitted in the 111 examples of Figs. 2 to 4).For example, d: In FIG. 2, when only V polarization is used, the transversal filter 3 and the signal synthesis circuits 6k and 1 become unstable, and the delay circuit 9d and the control signal generator 1 are It is also possible to mix them, and the k composition can be simplified.

In detail above #ii', Ming 17 Lord 17, Father of the present invention 7'
(The JiIi wave interference cancellation circuit can stably eliminate cross-polarization interference even when there is a lot of waveform distortion, and it can suppress the occurrence of equipment errors and provide good communication even when there is a large amount of waveform distortion. (It has the effect of maintaining rh).

4. Drawing f7i'i Jl Una Akira Disciple 1shii Fj
, (A block diagram of a cross-polarized wave interference removal circuit from 1971, Fig. 2 is a block diagram of the first embodiment of the present invention, and Fig. 3 is a block diagram of the present invention using a transbar "Lill filter" in the intermediate frequency band. Block diagram of the second real MIJ example, FIG. 4 1r-l-I
(Applied to -19 modulation, 5 loaves 9 P'hook diagram of the third fhfp example of the present invention, Figure 5 (2! Block diagram of one saw embodiment of the Toraso 7 Virgino 1 filter used in the old Figure 3) , 51st n1(b) l/:!: Intermediate frequency -nzt-Lance Barzl filter σ) - da (block diagram of biit fl, h'56 shows JI, jli++ signal method, L
i+fli', ltribute 11 (1) in a block diagram of 0 examples of ``j bow launch and 11 times doh''.

], 2.3, 4.21. 22.23.23'.

24.24'... Transbar reel filter (baseband band), L], ], 2, l3
, 1・1-・To16... Signal synthesis circuit (intermediate frequency band), 8,9°28128', 29.29', 4
(1...Delay circuit (baseband band), 18 +
19 +50...Delay circuit (intermediate frequency A1)
), 7, 27... system (1i11 (s x generation circuit, 1
7.1.7'・Pa... Demodulator, 31~35.41~4
5.4]'~45', 51~55+51'~55'
....

Variable weight A; J circuit, 46.46'+56.56',
75... Addition, device, 6o... Error 4 output device, 7 (, 1, 70a.

701), 70C, 701J...Controller, 71
...Oscillator, 72 ...Correlator, 73...°
...Integrator, 74 pin inverter, 76...Low pass filter, 77...Attenuator.

Agent Kuroshi Uchihara 1 reed

Claims (1)

[Claims] (1) A first transversal filter that receives the received output of the polarized wave of Kl and performs waveform equalization; at least one delay circuit connected to the output of at least one of the first and second transversal filters and capable of changing a certain delay time;
2. Interfering the tA1 or the second polarized wave branched to the output of at least one of the first and second transversal filters and included in the received output of the second or first polarized wave +3 (at least one third transversal filter that generates a signal, and at least one that combines the output of the delay circuit and the output of the transversal filter of t1λ3). One No. 18 synthesis circuit, and each variable type of the first, second, and third transversal filters receives the output signals of the first and vJ2 transversal filters including at least the output of this signal synthesis circuit. Mitsuke is a cross-polarization interference removal circuit characterized by comprising a control signal generation circuit that generates a control signal for controlling the circuit. 2) The delay circuit, the No. 18 synthesis circuit, and the third transformer. and a bar filter provided symmetrically with respect to both the first and second polarized waves, respectively.
+Claim 1: A cross-polarization interference removal circuit according to claim 1. (3) The received outputs of the first and second polarized waves are demodulated baseband signals, and the first and second polarized waves are demodulated. Scope of Patent No. 11 ATT Requested Item 1-i/ ζ is the differential polarization elimination circuit described in Section 2. (4) The received outputs of the first and second polarized waves are i
The first and second transversal filters have in-phase and autogonal inputs and outputs, respectively, with the baseband signals of two rows of cross-modulated waves that have been subjected to ffl F, lrt, and the third transversal filter are respectively the first
and the in-phase and quadrature outputs of the second transversal filter, and are connected to the in-phase and quadrature outputs of the first and second transversal filters, respectively. The output of the delay circuit and the in-phase of the second and first transversal filters and the output of the third transversal filter of h'+1 which is branched and connected to the 4-channel output are combined. It has been done / ζ front A [: % Ff'
1. The cross-polarization interference removal circuit according to item 3. (5) The received outputs of the polarized waves of the IIF system 1 and SOS 2 are intermediate frequency signals, and the received outputs of the IIF system polarized waves are intermediate frequency signals. The second and third transversal filters, the delay circuit, and the signal synthesis circuit are composed of intermediate frequency band circuits, and niJ f
tt, the cross-polarized wave according to claim 1 or 2, wherein a demodulator is inserted between the signal synthesis circuit or the first or second transversal filter and the control signal generation circuit, respectively. Interference cancellation circuit. (6) The control signal generation circuit converts the control signal of the third transversal filter into an originally independent demodulated pacepantoy signal of the polarized wave whose interference is to be removed and its estimated value. Claim 1.2.3 wherein the error signal is generated by determining the correlation between the error signal determined from the difference and the essentially independent demodulated baseband signal of the interfering polarization. .4 or 5. The cross-polarization interference removal circuit. (7) The control signal generation circuit superimposes perturbation signals of orthogonal frequencies on the control signals that control each variable ratio equalization circuit of the third transversal filter, and interference is removed. The above-mentioned claim is configured to generate "C" by determining the correlation between the error signal obtained from the difference between the demodulated baseband signal, which is essentially independent of the power polarization, and its estimated angle, and the perturbation signal. Range 1.
2. The cross-polarization interference removal circuit according to item 2, 3.4 or 5.