JPH08149058A - Diversity controller - Google Patents

Abstract

PURPOSE: To input the signal of the highest level and not to input the signal of a high level and a narrow band by switching the working antenna to another that inputs the signal having the highest receiving level of a correlation signal and also having the lowest level of the signal of a high level and a narrow band. CONSTITUTION: The AGC data stored in a storage part 10 are compared with each antenna number by a comparator 11, and these comparison results are outputted. The levels of the signals sent from a signal distributor 3a are detected at a level detecting part 13 and stored in a level storage part 16. At the same time, the level signals sent from the part 13 are compared with the reference voltage at a level deciding part 15a, and these level decision results are stored in the part 16. A control part 12 controls a switching part 3 to receive through an antenna the signal of the highest receiving level producing a correlation signal and the signal having a low level of a signal of a high level and a narrow band based on the AGC data comparison result of each antenna number stored in the part 10, the presence/absence detection data on the correlation data stored in the part 10, and the level detection data and the level decision result which are stored in the part 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to switched diversity among spatial diversity, and more particularly to AGC.
Spread spectrum communication diversity receiver.

[0002]

2. Description of the Related Art Diversity as a technique for multipath fading is "spatial diversity",
"Frequency diversity", "Time diversity",
"Directional diversity", "Polarization diversity",
"Electromagnetic field diversity" is considered. The "spatial diversity" is classified into the reproduction method of the demodulated signal and is classified into the "switching type" shown in FIG. 4, the "straight line combining type" shown in FIG.
Three types of “square-combination type” shown in FIG. 6 are known as typical ones. Among the above, "switching type diversity" is provided with a changeover switch at the antenna input end as shown in Fig. 4 to switch a plurality of antennas, detect and compare input levels, and select the antenna that gives the best signal. Is the way to do it.

Conventionally, as shown in FIG. 7, a switching type diversity receiver has a plurality of antennas spatially separated from each other, a changeover switch for selecting the antennas by a control signal, and an RF signal from the selected antennas. An RF / IF converter that selectively amplifies and converts the RF frequency band to an intermediate frequency band, and a level detector that detects the level of the signal from the RF / IF converter that is input to the detection circuit, and this level A storage unit that stores signals, a comparison unit that compares the stored level signals, and a control unit that controls the changeover switch based on the comparison result of the comparison unit. It is controlled so that the signal level can be obtained. As one method, the plurality of antennas are sequentially switched, the levels of the intermediate frequency signals from the RF / IF conversion unit are stored and compared, and the antenna having a higher level is selected and switched. As another method, the plurality of antennas are sequentially switched, the levels of the intermediate frequency signals from the RF / IF conversion unit are stored and compared, and a high level signal is left in the storage unit to finally obtain the highest level signal. I try to leave a signal.

However, when the above method is applied to a spread spectrum (direct spread) modulation system, the spread spectrum signal has a much wider band than the general narrow band modulation signal and the signal level is also high. Since the signal level is low, there is a problem in that if a narrow-band signal that is not spectrum-spread exists in the same frequency band, the antenna that inputs the narrow-band signal will be erroneously selected by simply comparing the signal levels. Also, if a signal spread-modulated with another spreading code is input at a higher level than the spread-modulated signal that is originally intended to be received, the antenna to be input at a high level may be erroneously selected. was there. In either case, signals other than the desired signal are input at a higher level, making it difficult to demodulate the signal.
The characteristic of spread spectrum modulation, which is inherently resistant to interference, is lost.

In order to solve these problems, in the case of the spread spectrum communication system, as shown in FIG. 8, detection is performed by using the correlation signal which is the output of the SAW (surface acoustic wave) matched filter used for the demodulation processing. A method is conceivable in which the detected signal to be converted is converted into an absolute value signal, the levels of the absolute value signal are compared, and the antenna is switched. However, this method can be used because the correlation signal has a level proportional to the reception level without the AGC circuit, but when the AGC circuit is added and the correlation signal is automatically controlled to a constant level, the absolute value signal Since there is no level difference, the levels cannot be compared and cannot be used.

Therefore, it is conceivable to use the AGC signal for controlling the AGC amplifier as the comparison signal. In this case, however, the AGC signal becomes maximum when an incorrect signal having no correlation signal is received. There is a problem that the correct antenna cannot be selected, and in order to solve this problem, as shown in FIG. 9, the level of the AGC signal corresponding to each antenna and the presence or absence of the correlation signal are stored in the storage unit,
It is considered that the levels of AGC signals having a correlation signal are compared with each other and the antenna is controlled to be selected based on the comparison result.

By the way, in the theory of spread spectrum modulation of the direct spread system, since the signal is spread over a wide area,
It is said that it is strong against interference by "high level narrow band signal", but it does not mean that there is no influence at all, and better quality communication is possible without such "high level narrow band signal". become. However, the above-mentioned diversity control device controls regardless of the presence or absence of the "high level narrow band signal", so there is a possibility that the "high level narrow band signal" may be received. .

[0008]

SUMMARY OF THE INVENTION The present invention solves the problems described above, inputs a correct spread spectrum signal of the highest level, and has a high input level of a "high level narrow band signal". An object of the present invention is to provide a diversity control device with AGC for spread spectrum communication that selects an antenna that does not input a signal.

[0009]

In order to solve the above problems, the present invention provides a plurality of antennas spatially separated from each other,
A changeover switch that selects the antenna by a control signal, a signal distributor that distributes the signal that is selected by the changeover switch, and a spread spectrum modulation signal from the signal distributor is selectively amplified to change from an RF frequency band to an intermediate frequency band. An RF / IF conversion unit for conversion, a detection circuit for inputting the intermediate frequency signal and outputting a detection signal, and an absolute value circuit unit for converting the detection signal from the detection circuit into an absolute value signal and outputting the absolute value signal, The RF from the absolute value signal from the absolute value circuit section
AGC circuit for generating an AGC signal for controlling the / IF converter, a first A / D converter for converting the AGC signal from the AGC circuit into a digital signal, and an absolute value signal from the absolute value circuit for correlation. A correlation signal detection circuit for detecting a signal, a storage unit for temporarily storing the detection data from the correlation signal detection circuit and the AGC data from the first A / D conversion unit, and the plurality of storage units stored in the storage unit. A comparator for comparing the AGC data corresponding to the antenna, a level detector for detecting the signal level from the signal distributor, and a second A / D converter for converting the detected level signal into a digital signal,
A level judgment unit for judging that the detection level signal is larger than a predetermined level; a level storage unit for storing level data from the second A / D conversion unit and a judgment result from the level judgment unit; A level comparison unit that compares the level data stored in the storage unit, a comparison result from the comparator and correlation data corresponding to a plurality of antennas stored in the storage unit, a comparison result and a level determination result of the level comparison unit And a control unit that outputs a control signal for controlling the changeover switch based on the above, sequentially switching the antennas by the control signal from the control unit, receiving the signal with the highest reception level with correlation signal detection data, and,
The antenna which does not receive the high level signal of the high level narrow band signal is selected.

[0010]

According to the diversity receiving apparatus of the present invention, the signals from a plurality of antennas are distributed by the distributor, and the spread spectrum modulated signal is converted from the distributed signals by the RF / IF converter. Selective amplification and gain control with, convert to an intermediate frequency band, delay detection of the correlation signal obtained by passing the signal in the intermediate frequency band through a SAW matched filter, convert this into an absolute value signal with an absolute value circuit, The AGC signal created from the absolute value signal is used as the RF signal.
/ IF conversion section, and a digital signal is converted into a digital signal, the converted AGC data is compared for each antenna, correlation signal detection data for detecting a correlation signal from the absolute value signal, and the distributor. Signal level is compared with a predetermined level to detect the presence / absence of a high-level narrow band signal, and based on the result of comparing the levels of the high-level narrow band signal, the control unit receives a signal with a correlation signal. The antenna is switched to the one that inputs the signal having the highest level and the lowest high level narrow band signal level.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A diversity receiver according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a diversity control device according to the present invention. In the figure, 1 is a first antenna and 2 is a second antenna. Reference numeral 3 denotes a changeover switch, which switches the antenna 1 and the antenna 2 by a control signal from the control unit 13. A signal distributor 3a distributes and outputs the RF signal from the changeover switch 3. 4 is R
In the F / IF converter, the spread band modulated RF band signal selected and input by the changeover switch is selected by the band pass filter (BPF) 41, and the linear amplifier 4
The signal is amplified by 2, further, the AGC amplifier 43 makes the level constant by the AGC signal, and the down converter 44 converts the signal into an intermediate frequency band signal. Reference numeral 5 denotes a detection circuit section, which includes a SAW matched filter 51 that receives a signal modulated by a spreading code to be received and obtains a correlation signal, and a delay circuit 52 that delays the correlation signal by one spreading period. , A multiplier 53 that outputs the delayed detection signal by multiplying the correlation signal before the delay and the correlation signal after the delay, and the LPF that outputs the detection signal by cutting the high frequency component of the delayed detection signal. (Low-pass filter) 54. An absolute value circuit unit 6 converts the detection signal into an absolute value signal.

Reference numeral 7 denotes an AGC circuit, which receives the absolute value signal and performs peak detection, a peak detection circuit 71, a loop filter 72 for converting the peak detection signal into a smooth signal, and a reference for comparing the signal with a reference signal. It is composed of a comparison circuit 73 and a DC offset circuit 74 for offsetting a DC component,
The AGC signal is generated. 8 is an A / D converter,
The AGC signal is converted into a digital signal to obtain AGC data. A correlation signal detection circuit 9 detects the presence or absence of a correlation signal from the absolute value signal and outputs the detection signal as correlation detection data. A storage unit 10 stores the AGC data and the detection data corresponding to the plurality of antenna numbers. A comparator 11 compares the AGC data stored in the storage unit and inputs the comparison result to the control unit 12. Reference numeral 12 denotes the control unit based on the input comparison result, the correlation detection data stored in the storage unit 10, the level comparison result from the level comparison unit 17, and the level determination result stored in the level storage unit 16. The changeover switch 3 is controlled to be changed over.

Reference numeral 13 is a level detector, which is the signal distributor 3
The signal level from a is detected. 14 is the second A /
The D converter converts the signal level from the level detector into a digital signal. Reference numeral 15 is a level determination unit, and whether the signal level from the reference voltage unit 15b that generates a predetermined reference voltage and the level detection unit 13 is higher than the reference voltage,
It is configured with a level determination unit 15a that determines whether the level is small, and determines whether or not there is a high level narrow band signal. The level storage unit 16 stores the level data from the A / D conversion unit 14 and the determination result from the level determination unit 15. Reference numeral 17 denotes the level comparison unit, which compares the signal levels corresponding to the plurality of antennas stored in the level storage unit.

FIG. 2 is a block diagram showing another embodiment of the diversity control device according to the present invention. In the figure,
Those having the same functions as those in FIG. 1 use the same symbols. 12
Reference numeral a denotes the control unit, the input comparison result, the correlation detection data stored in the storage unit 10, and the level storage unit 16
The changeover switch 3 is controlled to be switched based on the level detection results corresponding to the plurality of antennas stored in a.

The operation of the above arrangement will be described below. First, FIG. 1 will be described. A spread-spectrum-modulated RF signal input from the first antenna 1 is selected by the changeover switch 3 according to a control signal from the control unit 12, and is input to the RF / IF conversion unit 4 via the signal distributor 3a. After selective amplification and leveling, the IF signal S1 in the intermediate frequency band shown in FIG. The IF signal S1 is the SAW matched filter 5
1 to obtain the correlation signal S2 shown in FIG. 3-b, perform delay detection through the delay circuit 52 and the multiplier 53, and cut the high frequency component through the LPF 54 to obtain the detection signal S3 shown in FIG. . The detected signal S3 is converted into an absolute value signal S4 shown in FIG.
And to the correlation signal detection circuit 9. The absolute value signal S4 is peak-detected by the AGC circuit 7, converted into a DC signal through a loop filter, and compared with a reference signal, and then the DC component is offset to obtain an AGC signal. This AGC signal controls the AGC amplifier 43 and also
It is converted into a digital signal by the D converter 8 and stored in the storage unit 10 as AGC data corresponding to the antenna number. For the absolute value signal S4, the presence or absence of a correlation signal is detected by the correlation signal detection circuit 9, and this detection data is stored in the storage unit 10 in correspondence with the antenna number. The stored AGC data is compared by the comparator 11 for each antenna number, and the comparison result is output. Also, the signal distributor 3
The signal from a has its level detected by the level detection unit 13,
The detection signal is converted into a digital signal by the A / D conversion unit 14 and stored in the level storage unit 16. Further, the level signal from the level detection unit 13 is compared with a predetermined reference voltage from the reference voltage unit 15a in the level determination unit 15a to determine whether it is larger or smaller, and the level determination result is stored in the level storage unit. I remember. The control unit 12 stores the AGC data comparison result for each antenna number stored in the storage unit 10, the presence / absence detection data of the correlation data stored in the storage unit 10, the level detection data and the level determination result stored in the level storage unit 16. On the basis of the above, a signal with the highest reception level for generating a correlation signal, and to receive a low level signal of the high level narrow band signal from the antenna,
The switching unit 3 is controlled.

In the case of FIG. 2, for the signal from the signal distributor 3a, the level of the signal detected by the level detector 13 is compared with the reference voltage, and the determination result is stored in the level memory 16 as the level determination result. To be done. The control unit 12 a, based on the AGC data comparison result for each antenna number stored in the storage unit 10, the presence / absence detection data of the correlation data stored in the storage unit 10, and the level determination result stored in the level storage unit 16, The switching unit 3 is controlled so that a signal having the highest reception level for generating a correlation signal and having no high-level narrow band signal is received from the antenna.

[0017]

As described above, according to the diversity receiver of the present invention, the signals from the plurality of antennas are distributed by the distributor, and the spread spectrum modulated signal is converted from the distributed signals into the RF / IF converter. Selective amplification with
Gain control is performed, the signal is converted to an intermediate frequency band, the correlation signal obtained by passing the signal in the intermediate frequency band through a SAW matched filter is differentially detected, and this is converted to an absolute value signal by an absolute value circuit, The AGC signal is fed back to the RF / IF converter, converted into a digital signal, and the converted AGC data is compared for each antenna, and correlation signal detection data for detecting a correlation signal from the absolute value signal. Further, by comparing the signal level from the distributor with a predetermined level to detect the presence or absence of a high level narrow band signal, and based on the result of comparing the levels of the high level narrow band signal, the control unit , The reception level of the correlation signal is the highest, and since the signal is switched to the antenna that inputs the lowest level of the high level narrow band signal level, Provides a diversity control device with AGC for spread spectrum communication that selects the antenna that receives the highest level of the spread spectrum signal and does not input the high level narrow band signal can do.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a diversity control device according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the diversity control device according to the present invention.

FIG. 3 shows a signal waveform of a main part of a diversity control device for spread spectrum communication with AGC according to the present invention.

FIG. 4 is a block diagram showing a conventional diversity receiver.

FIG. 5 is a block diagram showing a conventional diversity receiver.

FIG. 6 is a block diagram showing a conventional diversity receiver.

FIG. 7 is a block diagram showing a conventional switched diversity receiver.

FIG. 8 is a block diagram showing a conventional diversity control device for spread spectrum communication.

FIG. 9 is a block diagram showing a conventional diversity controller for spread spectrum communication with AGC.

[Explanation of symbols]

 1 1st antenna 2 2nd antenna 3 Changeover switch 4 RF / IF conversion part 5 Detection circuit part 6 Absolute value circuit 7 AGC circuit 8 A / D conversion part 9 Correlation signal detection circuit 10 Storage part 11 Comparator 12 Control part 12a control unit 13 level detection unit 14 second A / D conversion unit 15 level determination unit 15a level determination unit 15b reference voltage unit 16 level storage unit 17 level comparison unit 41 band pass filter 42 linear amplifier 43 AGC amplifier 44 down converter 51 SAW matched filter 52 Delay circuit 53 Multiplier 54 Low-pass filter 71 Peak detection circuit 72 Loop filter 73 Reference comparison circuit 74 DC offset circuit

Claims (6)

[Claims] 1. A plurality of antennas spatially separated from each other, a changeover switch for selecting the antennas by a control signal, a signal distributor for distributing a signal selected by the changeover switch, and a spectrum from the signal distributor. An RF / IF converter that selectively amplifies the spread modulation signal and converts it from an RF frequency band to an intermediate frequency band, a detection circuit that inputs the intermediate frequency signal and outputs a detection signal, and a detection signal from the detection circuit To an absolute value signal, and an AG for generating an AGC signal for controlling the RF / IF converter from the absolute value signal from the absolute value circuit.
A C circuit, an A / D converter for converting an AGC signal from the AGC circuit into a digital signal, and a correlation signal detection circuit for detecting a correlation signal from the absolute value signal from the absolute value circuit,
A storage unit that temporarily stores the detection data from the correlation signal detection circuit and the AGC data from the A / D conversion unit; and a comparator that compares the AGC data corresponding to the plurality of antennas stored in the storage unit, A level detection unit that detects a signal level from the signal distributor, a level determination unit that determines the detection level, a level storage unit that stores level determination results corresponding to the plurality of antennas, and a comparator A control unit that outputs a control signal for controlling the changeover switch based on the comparison result, the correlation data corresponding to the plurality of antennas stored in the storage unit, and the level determination result corresponding to the plurality of antennas stored in the level storage unit. And the antenna is sequentially switched by the control signal from the control unit, and the signal with the highest received level with correlation signal detection data is received. And, diversity control unit, characterized in that so as to select an antenna that does not receive a high-level narrow-帶域 signal. 2. A plurality of antennas spatially separated from each other, a changeover switch for selecting the antennas by a control signal, a signal distributor for distributing a signal selected by the changeover switch, and a spectrum from the signal distributor. An RF / IF converter that selectively amplifies the spread modulation signal and converts it from an RF frequency band to an intermediate frequency band, a detection circuit that inputs the intermediate frequency signal and outputs a detection signal, and a detection signal from the detection circuit To an absolute value signal, and an AG for generating an AGC signal for controlling the RF / IF converter from the absolute value signal from the absolute value circuit.
A C circuit, a first A / D converter for converting an AGC signal from the AGC circuit into a digital signal, a correlation signal detection circuit for detecting a correlation signal from the absolute value signal from the absolute value circuit, and the correlation A storage unit that temporarily stores the detection data from the signal detection circuit and the AGC data from the first A / D conversion unit, and a comparator that compares the AGC data corresponding to the plurality of antennas stored in the storage unit. A level detector for detecting a signal level from the signal distributor, a second A / D converter for converting the detected level signal into a digital signal, and determining that the detected level signal is higher than a predetermined level For comparing the level data stored in the level storage unit, the level data stored in the level storage unit for storing the level data from the second A / D conversion unit and the determination result from the level determination unit. Control unit for controlling the changeover switch based on a comparison result from the comparator, correlation data corresponding to a plurality of antennas stored in the storage unit, a comparison result from the level comparison unit and a level determination result. It is composed of a control unit that outputs a signal, the antenna is sequentially switched by the control signal from the control unit, the signal with the correlation signal detection data and the highest reception level is received, and the high level narrow band signal is high. A diversity control device characterized in that an antenna that does not receive a level signal is selected. 3. The diversity control device according to claim 1, wherein the storage unit includes a plurality of registers. 4. The control unit is configured to sequentially switch the plurality of antennas when the power is turned on and when a reception channel in the RF / IF conversion unit is switched. The diversity control device according to claim 2. 5. The level determination unit includes a reference voltage unit that generates a predetermined reference voltage, and a level determination unit that compares the signal level from the level detection unit with the reference voltage and sends the magnitude result. The diversity control device according to claim 1 or 2, characterized in that 6. The level determination section includes a detection section for detecting the level of a signal, and an A for converting the detected signal into a digital signal.
A / D converter, a table storing a predetermined threshold value,
The diversity control device according to claim 1 or 2, wherein the diversity control device comprises a level comparison data obtained by the A / D conversion and a data comparison unit for comparing threshold values from a table.