JPH10150380A - Millimeter wave FSK transmission / reception system - Google Patents

Abstract

(57) Abstract: The present invention relates to a millimeter wave FSK transmission / reception system, and an object thereof is to provide a millimeter wave FSK transmission / reception system capable of absorbing frequency fluctuations and performing stable reception. And SOLUTION: An FSK modulation circuit for receiving data input and converting the data into an intermediate frequency, transmission frequency conversion means for mixing an output of the modulation circuit with an output carrier of a local oscillation circuit and converting the output into upper and lower side waves, At least one transmitting antenna for wirelessly transmitting an output of the converting means, at least one receiving antenna for receiving a radio signal from the transmitting antenna, and receiving an output of the receiving antenna to receive a received upper and lower sideband signal Receiving frequency converting means for separating and converting the frequency into an intermediate frequency band corresponding to the above, an IF band demodulating circuit independently provided for receiving the two outputs of the receiving frequency converting means and demodulating it into the original signal; Adding means for adding the output of the IF band demodulation circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a millimeter wave FSK (Fr
More specifically, the present invention relates to a transmission / reception system, and more particularly, to a millimeter-wave FSK transmission / reception in which one master station in a millimeter-wave band and N child stations perform wireless communication in which high-quality communication is required in private communication where multiple reflections occur. About the system.

[0002]

2. Description of the Related Art Conventionally, there is a TDMA system as a system for wirelessly communicating with one master station and N slave stations. The TDMA system controls the transmission timing of a signal transmitted from each terminal so that the signals do not collide when a plurality of wireless stations use the same frequency. Each wireless station transmits a signal only in a specific time slot allocated in time.

In this case, a line (uplink) transmitted from a slave station to a master station is transmitted as a burst signal obtained by temporally compressing a continuous signal sequence. When a frame format with a short burst length is used, it is difficult for the receiving circuit of the master station to adopt the synchronous detection method, and when a local oscillator of a slave station that allows easy frequency stability is adopted, the master station arrives. A frequency deviation of the carrier wave occurs between burst signals from different slave stations, and the normal FSK / frequency discrimination detection method has a problem that the code error rate is greatly deteriorated due to the frequency fluctuation.

Here, the FSK / frequency discrimination detection method is to assign numerical values "0" and "1" to different frequencies f1 and f2, respectively, as shown in FIG. Therefore, in order to recover data from a signal transmitted by such a modulation method, the frequency is demodulated to numerical values “0” and “1” by a frequency discrimination detection method.

In order to eliminate the drawbacks of the conventional FSK / frequency discrimination detection system, a differential FSK partial response detection system (DFSK) is used. This DFSK method is different from a normal FSK / frequency discrimination detection method in that a baseband signal sequence before modulation is subjected to a difference calculation of a baseband signal sequence and a full-wave rectification after a baseband signal sequence in a stage subsequent to the frequency discrimination detection circuit. A receiving circuit for identification is added to improve a code error rate (bit error rate) caused by frequency fluctuation.

FIG. 14 is a diagram showing an example of a transmission / reception circuit of the differential FSK partial response system. The hatched circuit portion in the figure is a conventional component, and a circuit other than the hatched is newly added.

Transmission data enters one input of the exclusive OR circuit 1. Then, the output of the exclusive OR circuit 1 enters the delay flip-flop circuit 2. Part of the output of the delay flip-flop circuit 2 is input to the other input of the exclusive OR circuit 1. Therefore, the exclusive OR circuit 1 takes the exclusive OR of the input data and the input data one clock before.

The exclusive OR circuit 1 and the delay flip-flop circuit 2 constitute a transmission code conversion circuit. After the output of the exclusive OR circuit 1 is delayed by the delay flip-flop circuit 2, the frequency modulation circuit (FM)
MOD) 3, undergoes modulation as shown in FIG. 13 by the frequency modulation circuit 3, and is transmitted as a modulation output (MOD OUT).

[0009] On the other hand, the received data enters a limiter circuit (LIM) 4, is subjected to band limitation, and is frequency-discriminated by a subsequent frequency discrimination circuit (DISC) 5 to be output. The output of the frequency discrimination circuit 5 is
Distributed in the direction. One output of the signal distributor 6 enters a positive input of a differential amplifier (DAMP) 8. The other output of the signal distributor 6 enters the negative input of the differential amplifier circuit 8 after being delayed by the one-bit delay 7.

The differential amplifier 8 amplifies the difference between the output of the signal distributor 6 and the output of the one-bit delay 7. And
After its output is full-wave rectified by the full-wave rectifier circuit 9,
The data modulated by the identification circuit (DEC) 10 is demodulated to the original data, and becomes a data output.

[0011]

In the above-described differential FSK partial response system, since the received signal has a ternary eye pattern, the required Eb / No (bit energy / noise energy ratio) is ,
Compared to the FSK frequency discrimination detection method, the signal is degraded by 1.7 dB, and the modulation index is degraded by 3.8 dB at 0.7. This means that as the frequency fluctuation increases, the bit error rate (BE)
R) deteriorates.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a millimeter-wave FSK transmission / reception system capable of absorbing frequency fluctuations and performing stable reception. The purpose is.

[0013]

[Means for Solving the Problems]

(1) FIG. 1 is a principle block diagram of the present invention. In the figure, the same components as those in FIG. 14 are denoted by the same reference numerals.
In the figure, reference numeral 3 denotes an FSK modulation circuit which receives a data input and converts it to an intermediate frequency; 20 denotes a transmission frequency conversion means for mixing an output of the modulation circuit 3 with an output carrier of a local oscillation circuit to convert the output into upper and lower side waves; Is at least one transmission antenna for transmitting the output of the transmission frequency conversion means 20 wirelessly. These FSK modulation circuit 3 and transmission frequency conversion means 2
0 and the transmitting antenna 11 show the configuration on the slave station side.

Reference numeral 12 denotes at least one receiving antenna for receiving the radio signal from the transmitting antenna 11, and 30 receives the output of the receiving antenna 12 and separates it into an intermediate frequency band corresponding to the received upper and lower sideband signals. Frequency conversion means for frequency conversion.

Reference numerals 41 and 42 denote IF band demodulation circuits independently provided for receiving the two outputs of the reception frequency conversion means 30 and demodulating them into the original intermediate frequency signal. It is an adding means for adding outputs. 4
Reference numeral 4 denotes a code reproducing circuit which receives the output of the adding means 43 and reproduces a code. These receiving antenna 12, receiving frequency converting means 30, IF band demodulating circuits 41 and 42, adding means 4
3 and the code reproducing circuit 44 show the configuration on the master station side.

According to the configuration of the present invention, the FSK modulated wave in the IF band is transmitted in the upper and lower sidebands by the transmission frequency conversion means 20 by utilizing the wideband characteristic in the millimeter waveband, and the sideband is transmitted on the receiving side. Are converted into IF bands (IF1 and IF2) corresponding to both sidebands, and the intermediate frequencies of the respective sidebands are detected by IF band demodulation circuits 41 and 42 and demodulated to basebands BB1 and BB2. Then, the demodulated baseband signal is added by the adding means 43 so that the signal (BB) in which the frequency variation in the upper and lower sidebands is reduced to 0
3) can be obtained, and a stable reception can be performed by absorbing the frequency fluctuation.

(2) In this case, it is assumed that one transmission antenna transmits linearly polarized waves or circularly polarized waves, and that the transmitted linearly or circularly polarized waves are received by one receiving antenna. Features.

According to the configuration of the present invention, with a simple configuration in which one antenna is provided on each of the transmitting side and the receiving side, stable reception can be performed by absorbing the fluctuation even when the frequency fluctuates.

(3) Also, two antennas for transmitting an upper band wave and two antennas for transmitting a lower band wave are used as the transmitting antennas, and these antennas transmit linearly or circularly polarized waves. It is characterized in that a certain linearly or circularly polarized wave is received by one receiving antenna.

According to the configuration of the present invention, the number of antennas on the transmitting side is set to two, and transmission is performed by different antennas for each of the upper and lower sidebands, so that interference on the transmitting side can be reduced.

(4) In addition, one transmitting antenna transmits linearly polarized light or circularly polarized wave, and the linearly polarized wave or circularly polarized wave which is the transmission wave is transmitted to an antenna for transmitting an upper band and a lower band for an antenna. It is characterized in that reception is performed by two receiving antennas for transmitting.

According to the configuration of the present invention, the number of reception-side antennas is two, and reception is performed by different antennas for each of the upper and lower sidebands, so that interference on the reception side can be reduced.

(5) Further, as a transmission code format from the transmission frequency conversion means, a zero continuous suppression code is used in addition to a bipolar code, a Manchester code, or a CMI code.

According to the configuration of the present invention, by using a code having a small DC component such as a bipolar code, a Manchester code, or a CMI code as a code format, it is possible to reduce an error when a code is level-identified by a comparator. it can.

(6) Further, 2 corresponding to the upper and lower sidebands
The combined signal of the baseband signals is added by the adding means, and when the result of the addition is identified by a code reproducing circuit that identifies the reference level, and the input level of the code reproducing circuit corrects the identification level. And a comparison reference signal correcting means for providing the same.

According to the configuration of the present invention, the discrimination level is adjusted by the comparison reference signal correcting means, so that the discrimination level can be brought to the middle point of the composite waveform. Can be correctly encoded.

FIG. 2 is a block diagram showing a first embodiment of the present invention. In this embodiment, one antenna is provided on each of the transmitting side and the receiving side. FIG.
The same components are denoted by the same reference numerals. On the transmitting side, 21 receives the output IF of the FSK modulation circuit 3 and mixes it with the output carrier of the local oscillation circuit to form upper and lower sidebands (USB
And LSB), and a transmission local oscillation circuit 22 that provides the transmission frequency conversion circuit 21 with the output carrier ftlo.

These transmission frequency conversion circuit 21 and transmission local oscillation circuit 22 constitute transmission frequency conversion means 20 of FIG. Two outputs U of the transmission frequency conversion circuit 21
The SB and LSB are transmitted from a transmitting antenna (T ANT) 11.

On the receiving side, 31 is a receiving antenna (R
ANT) 12 receives a signal received, separates the signal into intermediate frequency bands IF1 and IF2 corresponding to the received upper and lower sideband signals, and converts the frequency. This is a receiving local oscillation circuit that provides frlo. These receiving frequency conversion circuits 3
1 and the reception local oscillation circuit 32 constitute the reception frequency conversion means 30 of FIG.

Reference numeral 41 denotes a first IF band demodulation circuit for receiving the output intermediate frequency band IF1 of the reception frequency conversion circuit 31 and demodulating it to the original baseband. Reference numeral 42 denotes a reception frequency conversion circuit 31.
Is a second IF band demodulation circuit that receives the output intermediate frequency band IF2 and demodulates it to the original baseband. The baseband signal BB1 is output from the first IF band demodulation circuit 41, and the baseband signal BB2 is output from the second IF band demodulation circuit.

Reference numeral 43 denotes the baseband signals BB1 and BB
2 is an operational amplifier circuit as an adding means for receiving and adding 2. A code reproducing circuit 44 receives the output BB3 of the operational amplifier circuit 43 and reproduces the original code data. The operation of the circuit thus configured will be described as follows.

FSK modulation circuit 3 for performing FSK modulation of input data (DATA IN) in an intermediate frequency (IF) band
, And the modulated output signal IF is input to a transmission frequency conversion circuit (up-converter) 21.

The transmission frequency conversion circuit 21 mixes with the frequency ftlo given from the transmission local oscillation circuit 22 to generate an upper sideband signal USB (frequency f = ftlo + IFt);
The lower sideband signal LSB (frequency = ftlo−IFt) is output and transmitted from the transmitting antenna 11. Where IF
t is an intermediate frequency. In this case, the signal transmitted from the transmitting antenna 11 may be any of linearly polarized and circularly polarized waves (the same applies hereinafter).

The transmitted upper and lower sideband signals (USB and L
SB) is received by the reception antenna 12 of the master station, and is input to a reception frequency conversion circuit (down converter) 31 that separates sidebands by an image rejection mixer or the like. The reception frequency conversion circuit 31 receives the reception local oscillation frequency frlo substantially equal to the transmission local oscillation frequency ftlo, mixes the reception local oscillation frequency frlo with the reception local oscillation frequency frlo, and converts the reception local oscillation frequency frlo into an intermediate frequency signal IF1 corresponding to the upper sideband signal and a lower sideband signal. The corresponding intermediate frequency signal IF2 is separated and output.

The signal of IF1 enters a first IF band demodulation circuit 41 for performing band limitation, amplification and frequency discrimination detection.
The SK detection signal BB1 is output. Similarly, the second I
The F band demodulation circuit outputs an FSK detection signal BB2.

The baseband signals of BB1 and BB2 enter the subsequent operational amplifier circuit 43, and obtain an added and synthesized output BB3. The combined output BB3 is output to the code reproducing circuit 44.
To perform clock reproduction and identification, and the reproduced data pulse is output (DATAOUT).

The above-mentioned combined output BB3 is supplied to the operational amplifier 4
Assuming that the gain (gain) of No. 3 is G, BB3 = G (BB1 + BB2) (1)

Here, since the signal of BB2 corresponding to the lower sideband has a phase opposite to that of BB1 corresponding to the upper sideband, BB3 has the same characteristics as the transmission path.
Its amplitude is twice as large as BB1.

The bit error rate (BER) is approximately the same as that of the normal FSK frequency discrimination detection method because the noises of the upper and lower sideband signals are also combined, but is better than the differential FSK partial response.

On the other hand, assuming that the combined output of BB3 with respect to the frequency fluctuation of the local oscillation circuit fluctuates only by the transmission local oscillation frequency by Δf, the upper and lower sideband frequencies both increase by Δf. However, on the receiving side, IF
1 becomes higher by + Δf and IF2 becomes lower by −Δf. Therefore, assuming that the fluctuation of each frequency detection voltage due to the fluctuation of the reception IF is ΔE, the synthesized output BB3 is BB3 = G (BB1 + ΔE + BB2) with reference to the equation (1). −ΔE) (2), ΔE is canceled.

Therefore, similarly to the conventional differential FSK partial response system, no error occurs in the discrimination level due to the frequency fluctuation of the local oscillation circuit, and even when the burst signal from the slave station has a frequency deviation of Δf, the optimum discrimination level is obtained. Does not fluctuate.

According to the present embodiment, the FSK modulated wave in the IF band is transmitted in the upper and lower sidebands by the transmission frequency conversion means 20 by utilizing the broadband characteristic in the millimeter waveband, and the two sidebands are transmitted on the receiving side. The signals are converted into IF bands (IF1 and IF2) corresponding to both sidebands by a mixer that separates the bands, and the intermediate frequencies of the respective sidebands are detected by IF band demodulation circuits 41 and 42 and converted to basebands BB1 and BB2. By demodulating and adding the demodulated baseband signal by the adding means 43, the frequency fluctuation in the upper and lower sidebands can be reduced to 0,
Even for frequency fluctuations, the fluctuations can be absorbed and stable reception can be performed.

Further, according to this embodiment, a simple configuration in which one antenna is provided on each of the transmission side and the reception side allows stable reception by absorbing frequency fluctuations. Can be.

FIG. 3 is a block diagram showing a second embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. In the embodiment shown in the figure, a transmitting antenna on the transmitting side is provided for each of upper and lower sidebands for space diversity. 11a is a transmission antenna provided corresponding to the upper sideband, and 11b is a transmission antenna provided corresponding to the lower sideband. Other configurations are the same as those in FIG. The operation of the circuit thus configured will be described below.

The intermediate frequency IF signal modulated by the FSK modulation circuit 3 is converted by the transmission frequency conversion circuit 21 into upper and lower sidebands USB and LSB. And the upper sideband U
The SB is separated from the transmitting antenna 11a and the lower sideband LSB is separated from the transmitting antenna 11b and transmitted.

The received signal is converted into intermediate frequency (IF) signals by a receiving frequency conversion circuit 31 which separates the upper and lower sidebands of the image rejection mixer and the like into intermediate frequency (IF) signals. Is converted and output.

Outputs IF1 and IF2 of the reception frequency conversion circuit 31 are output from IF band demodulation circuits 41 and 42, respectively.
And baseband signals B corresponding to IF1 and IF2
Demodulated to B1 and BB2 and output. Operational amplifier circuit 4
3 adds the respective baseband signals BB1 and BB2, and outputs the addition result as BB3. BB3 does not include the frequency fluctuation.

The added baseband signal BB3
Enters the following code reproducing circuit 44, where the code is reproduced. According to this embodiment, by using two transmission antennas and transmitting the signals using different antennas for the upper and lower sidebands, it is possible to reduce interference on the transmission side.

FIG. 4 is a diagram showing an embodiment of the transmission frequency conversion circuit. The same components as those in FIG. 3 are denoted by the same reference numerals. The data input is an intermediate frequency modulation circuit (FS
K modulation circuit) 3 and is converted into an intermediate frequency IF.
Then, the output of the intermediate frequency modulation circuit 3 enters one port of the 90 ° hybrid 50. The other end of the 90 ° hybrid 50 is connected to a dummy load DL for termination. And the 90 ° hybrid 50
Generates a signal having a 90 ° phase difference between 0 ° and −90 °.

On the other hand, the local oscillation circuit 22
Generates a signal. This signal is 0 ゜ hybrid 51
Enter the port. The 0 ° hybrid 51 is in phase with 2
Generate two signals. The two outputs of the 0 ° hybrid 51 enter one port of the 90 ° hybrids 52 and 53, respectively.

The other port of the hybrid 52 receives the −90 ° output of the 90 ° hybrid 50 via a diode D, and the other port of the hybrid 53 receives the 0 ° output of the 90 ° hybrid 50. Input through a diode D.

The 90 ° hybrids 52 and 53 constitute a transmission balanced mixer, and the outputs of the 90 ° hybrids 52 and 53 enter the ports of the 90 ° hybrid 54. 90 ゜ Hybrid 54 is the upper sideband USB
And the lower sideband LSB, and transmits the signals from the respective transmitting antennas 11a and 11b.

As a transmission code format from the transmission frequency conversion means, a bipolar code, a Manchester code, or a CMI code can be used. Here, the Manchester code is a code corresponding to “1, 0” when the data is “0” and “0, 1” when the data is “1”.
As for the I code, “0” becomes “1”, “1” becomes “11”, “0”.
This code is designed to prevent the continuation of "0" by alternating "0".

According to this embodiment, by using a code having a small DC component such as a bipolar code, a Manchester code, or a CMI code as a code format, it is possible to reduce an error when a code is level-identified by a comparator. Can be.

According to the embodiment shown in FIG. 4, by combining a transmission balanced mixer and a hybrid, upper and lower sidebands can be separated without using a bandpass filter (BPF).

FIG. 5 is a block diagram showing a third embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. In the embodiment shown in the figure, a receiving antenna on the receiving side is provided for each of upper and lower sidebands for space diversity. 12a is a receiving antenna provided corresponding to the upper sideband, and 12b is a receiving antenna provided corresponding to the lower sideband. Other configurations are the same as those in FIG. The operation of the circuit thus configured will be described below.

The intermediate frequency IF signal modulated by the FSK modulation circuit 3 is converted by the transmission frequency conversion circuit 21 into upper and lower sidebands USB and LSB. And the upper sideband U
The transmission antenna 11 transmits the SB and the lower sideband LSB.

The received signal is received by receiving antennas 12a and 12b provided for the upper and lower sidebands, and enters a receiving frequency conversion circuit 31. A reception frequency conversion circuit 31 that separates upper and lower sidebands such as an image rejection mixer and converts the same into an intermediate frequency (IF) signal is converted into intermediate frequency signals IF1 and IF2 corresponding to the sidebands and output.

Outputs IF1 and IF2 of the reception frequency conversion circuit 31 are output to IF band demodulation circuits 41 and 42, respectively.
And baseband signals B corresponding to IF1 and IF2
Demodulated to B1 and BB2 and output. Operational amplifier circuit 4
3 adds the respective baseband signals BB1 and BB2, and outputs the addition result as BB3. Addition output BB
3 does not include the frequency fluctuation.

The added baseband signal BB3
Enters the following code reproducing circuit 44, where the code is reproduced. According to this embodiment, the number of reception antennas is two, and reception is performed by different antennas for each of the upper and lower sidebands, so that interference on the reception side can be reduced.

FIG. 6 is a diagram showing another embodiment of the transmission frequency conversion circuit, which shows the transmission frequency conversion circuit in FIG. In this embodiment, the IF band FSK modulated wave I
F outputs upper and lower sidebands USB and LSB by a balanced transmission mixer using a diode D and a 90 ° hybrid 60.

FIG. 7 is a diagram showing an embodiment of the reception frequency conversion circuit, and shows the reception frequency conversion circuit in FIG. The output of the local oscillation circuit 32 is 0 ゜ hybrid 6
1 and the 0 ° hybrid 61 outputs two frequency signals having the same phase, and the image rejection mixer 62
And 63 are entered. The image rejection mixer 62 is provided corresponding to the upper sideband USB, and the image rejection mixer 63 is provided corresponding to the lower sideband LSB.

The signal received by the receiving antenna 12a enters the image rejection mixer 62, and the signal received by the receiving antenna 12b enters the image rejection mixer 63. The image rejection mixer 62
The reception signal USB and the local transmission frequency are mixed to output an intermediate frequency signal IF1, and the image rejection mixer 63 mixes the reception signal LSB and the local transmission frequency to output an intermediate frequency signal IF2.

FIG. 8 is a diagram for explaining the effect of the present invention in space diversity. (A) is a data waveform,
(B) is a BB1 output waveform, (c) is a BB2 output waveform,
(D) is the waveform of BB3, which is the combined output of BB1 and BB2, and (e) is the identification pulse.

As in the case of the millimeter wave band, the directivity of the antenna can be sharpened, and the direct wave is larger than the reflected wave in the line of sight, and the relative delay time between the direct wave and the reflected wave is one of the period T of the modulation code. / 2 is shown.

The direct wave f1 and the delayed wave f2 are input to the upper side wave (USB) antenna, and the detection outputs of these signals are converted into a detection signal by the direct wave, a 1/2 delay of the symbol period T, and an amplitude of 1/3. Assuming that a detection signal is superimposed by a delayed wave, the lower side wave (LSB) detection signal from the receiving antenna receives only the LSB, and shows each baseband demodulated waveform when there is no detection output of the delayed wave. I have. F3 in (c) is B
B2 output.

A detection signal f2 based on a delayed wave is superimposed on BB1 as shown in FIG. On the other hand, BB2 output f
No delay wave component is superimposed on 3 as shown in FIG. When such BB1 and BB2 are added by the operational amplifier circuit 43, a combined waveform as shown in (d) is obtained.

In (d), f4 is the detection signals f1, f
2, f3 is a composite signal, and f5 is a composite waveform of the detection signals f1 and f3. In (d), Edec is an identification level. Such an offset may be superimposed on the composite waveform. That is, since the average value of the signal waveform after the addition operation increases, an identification error occurs when the signal waveform is fixed at the optimum identification level when no delay is caused. As a result, the required S / N of the bit error rate deteriorates.

Therefore, it is necessary to correct the DC component so that the discrimination level is exactly at the middle point of the composite waveform. In the example of FIG. 8, it is necessary to correct the DC voltage so that Edec is at the middle point of the composite waveform.

FIG. 9 is a diagram showing one embodiment of a space diversity comparison reference signal correction circuit. The intermediate frequency IF1 of the upper sideband USB in the reception frequency conversion circuit 31
To the intermediate frequency IF2 of the lower sideband LSB. These intermediate frequencies IF1 and IF2 are input to frequency discriminating circuits 65 and 66, respectively, and are converted into frequency signals.

The outputs of the frequency discriminating circuits 65 and 66 are supplied to an operational amplifier (op-amp) 43
a is added. Part of the output of the operational amplifier 43a enters a positive input of a comparator 44a constituting the code reproducing circuit 44 via a resistor. On the other hand, part of the output of the operational amplifier 43a enters a buffer amplifier 67, and the output of the buffer amplifier 67 enters a low-pass filter composed of a resistor R1 and a capacitor C1.

The output of the low-pass filter enters the negative input of the comparator 44a. The reference voltage Er is also input to the negative input of the comparator 44a via the resistor R2. According to such a configuration, a correction voltage for bringing the identification level Edec described with reference to FIG. 8 to the middle point of the composite waveform can be input from the low-pass filter to the negative input of the comparator 44a. It comes to the middle point of the composite waveform. Thereby, the comparator 44
a can correctly encode the original data.

When the discrimination level is changed in accordance with the speed of the fading change, the time constants of C1 and R1 of the low-pass filter may be determined in accordance with the fading change.

FIG. 10 is a diagram showing another embodiment of the space diversity comparison reference signal correction circuit. FIG.
The same components are denoted by the same reference numerals. In this embodiment, a clock is extracted from the output of the operational amplifier 43 a by a clock extraction circuit 68, and the extracted clock is input to a clock counter 69. The clock counter 66 counts a clock and generates a sample pulse at a predetermined cycle. The sample pulse is supplied to a sample hold circuit 70, the output of the operational amplifier 43a at this time is held, and the held voltage value is supplied to a comparator 44a as a DC voltage for correcting Edec. is there.

According to such a configuration, the comparator 4
A correction voltage for bringing the discrimination level Edec described with reference to FIG. 8 to the middle point of the composite waveform can be input from the sample and hold circuit 70 to the negative input of 4a.
ec comes to the middle point of the composite waveform. This allows
The comparator 44a can correctly encode the original data.

FIGS. 11 and 12 are diagrams for explaining the operation of the present invention.
FIG. 11 shows the operation on the transmitting side, and FIG. 12 shows the operation on the receiving side. The same components as those in FIG. 5 are denoted by the same reference numerals. On the transmitting side, point A is for data input and point B is FS
The output of the K modulation circuit 3 and the point C are the transmission frequency conversion
Respectively are shown.

The point D is an upper wave band-pass filter 31a.
, The point E the output of the lower sideband bandpass filter 31c, the point F the output of the IF bandpass filter 41b, the point G the output of the IF bandpass filter 42b, and the point H
Points indicate the output of the frequency discrimination circuit 41c, and point I indicates the output of the frequency discrimination circuit 42c. The vertical axis indicates the intensity of the frequency spectrum, and the horizontal axis indicates the frequency.

Normally, the transmission frequency conversion circuit 21 transmits signals at frequencies f _USB and f _LSB separated by IFt above and below the local oscillation frequency ftlo. Here, when the output of the transmission local oscillation circuit 22 fluctuates by ΔF, C
As indicated by the points, both the upper sideband outputs f _USB and f _LSB are + Δ
It increases by F.

On the receiving side, the receiving local oscillation circuit 32 generates a frequency frlo substantially equal to the output frequency ftlo of the transmitting local oscillation circuit 22. In FIG. 12, 31
a is a first bandpass filter (BPF1) which receives the output of the receiving antenna 12a and passes only the upper wave, 31
b receives the output of the band-pass filter 31a, mixes the output of the receiving local oscillation circuit 32, and mixes the intermediate frequency IF1.
The band-pass filter 31a and the mix circuit 31b constitute the reception frequency conversion circuit 31 shown in FIG.

Similarly, 31c is a second band-pass filter (BPF2) that receives the output of the receiving antenna 12b and passes only the lower side wave, and 31d receives the output of the band-pass filter 31c and receives the local oscillation circuit. 32, and outputs the intermediate frequency IF2. The band-pass filter 31c and the mix circuit 3
1d constitutes the reception frequency conversion circuit 31 of FIG.

The outputs of the respective mix circuits 31b and 31d enter IFA (IF amplifier) 41a and IFA (IF amplifier) 42a, and the outputs of IFA 41a and IFA 42a enter IFBF 41b and IFBF 42b, respectively.
The output of each IFBF 41b and IFBF 41e is
The frequency discriminating circuits 41c and 42c enter the frequency discriminating circuits 41c and 42c.
B2 is output. The outputs of BB1 and BB2 enter the adder 43 and are combined to form BB3.

The first IF band demodulation circuit 41 is constituted by the IF amplifier 41a, the IF band pass filter 41b and the frequency discriminating circuit 41c, and the second IF band is constituted by the IF amplifier 42a, the IF band pass filter 42b and the frequency discriminating circuit 42c. The IF band demodulation circuit 42 is configured.

In this case, if the transmitting local oscillation frequency ftlo fluctuates by ΔF on the transmitting side,
IF1 increases by ΔF and IF2 decreases by ΔF. When only the reception local oscillation frequency frlo fluctuates by ΔF, IF1 becomes lower by ΔF and IF2 becomes lower.
Increases by ΔF. In any case, the output of the adder 43 is one in which these fluctuation components have been removed, and it can be seen that there is no error in the identification voltage.

[0084]

As described above in detail, (1) According to the first aspect of the present invention, an FSK modulation circuit for receiving a data input and converting it to an intermediate frequency, and a local oscillation circuit for outputting an output of the modulation circuit Transmission frequency conversion means for mixing with an output carrier wave of the transmission frequency conversion means to convert the output of the transmission frequency conversion means into a radio wave, at least one transmission antenna for wirelessly transmitting an output of the transmission frequency conversion means, and at least a radio signal from the transmission antenna One receiving antenna, receiving frequency converting means for receiving the output of the receiving antenna, separating it into an intermediate frequency band corresponding to the received upper and lower sideband signals, and converting the frequency, and two outputs of the receiving frequency converting means An IF band demodulation circuit independently provided for receiving and demodulating the signal into an original signal;
And an adding means for adding the output of the band demodulation circuit, thereby making use of the broadband characteristic of the millimeter wave band.
The FSK modulated wave in the band is transmitted as upper and lower sidebands by the transmission frequency conversion means 20, and the IF band corresponding to the both sidebands (IF1, IF1,
IF2), and the intermediate frequency of each sideband is
The signal is detected by an F-band demodulation circuit, demodulated into basebands BB1 and BB2, and the demodulated baseband signals are added by an adding means 43 to reduce the frequency fluctuation in the upper and lower sidebands to zero.
And stable reception can be performed by absorbing the frequency fluctuation.

(2) According to the second aspect of the present invention, one transmission antenna transmits linearly polarized light or circularly polarized light, and one linearly or circularly polarized wave as the transmission wave is received by one transmission antenna. By receiving with an antenna, with a simple configuration in which one antenna is provided on each of the transmitting side and the receiving side, even a frequency fluctuation can be absorbed and stable reception can be performed.

(3) According to the third aspect of the present invention, two antennas for transmitting an upper band wave and two antennas for transmitting a lower band wave are used as the transmitting antennas, and linearly or circularly polarized waves are transmitted from these antennas. , And the linearly polarized wave or the circularly polarized wave, which is the transmission wave, is received by one receiving antenna, so that the number of transmitting antennas is reduced to two and transmitted by different antennas for each of the upper and lower sidebands. As a result, it is possible to reduce interference on the transmission side.

(4) According to the fourth aspect of the present invention, one transmission antenna transmits linearly polarized light or circularly polarized light, and the transmitted linearly or circularly polarized wave is transmitted to the upper band. By receiving two receiving antennas, one transmitting antenna and the other transmitting the lower sideband, the number of receiving antennas is reduced to two, and each of the upper and lower sidebands is received by a different antenna. Interference can be reduced.

(5) According to the fifth aspect of the present invention, the transmission code format from the transmission frequency conversion means can be a bipolar code, a Manchester code, a CMI code, or a zero continuous suppression code. By using a code with a small DC component such as a bipolar code, a Manchester code, or a CMI code, it is possible to reduce an error when the code is identified by the comparator.

(6) According to the invention described in claim 6, the combined signal of the two baseband signals corresponding to the upper and lower sidebands is added by the adding means, and the addition result is identified by the reference level. When the level is identified by the code reproducing circuit, and by providing a comparison reference signal correcting means for correcting the identification level at the input portion of the code reproducing circuit,
By adjusting the discrimination level by the comparison reference signal correction means, the discrimination level can be made to be at the midpoint of the composite waveform, whereby the comparator can correctly encode the original data.

As described above, according to the present invention, the tolerance of frequency fluctuation and phase jitter is wide, and
(Millimeter-wave monolithic IC), which makes it easy to suppress the degradation of the code error rate characteristic due to the carrier frequency fluctuation of the TDMA burst wave having a short frame. The required C / N is also a differential FSK partial. It can be better than the response detection method. Further, there is an advantage that space diversity for countermeasures against multipath interference is easy, and it is effective for a small and low-priced wireless system. Also,
Space diversity configuration is also easy.

As described above, according to the present invention, it is possible to provide a millimeter wave FSK transmission / reception system capable of absorbing frequency fluctuations and performing stable reception.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a block diagram illustrating a first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an embodiment of a transmission frequency conversion circuit.

FIG. 5 is a block diagram showing a third embodiment of the present invention.

FIG. 6 is a diagram showing another embodiment of the transmission frequency conversion circuit.

FIG. 7 is a diagram illustrating an embodiment of a reception frequency conversion circuit.

FIG. 8 is an explanatory diagram of an effect of the present invention.

FIG. 9 is a diagram showing an embodiment of a space diversity comparison reference signal correction circuit.

FIG. 10 is a diagram showing another embodiment of a space diversity comparison reference signal correction circuit.

FIG. 11 is a diagram illustrating the operation of the present invention.

FIG. 12 is a diagram illustrating the operation of the present invention.

FIG. 13 is an explanatory diagram of an FSK modulation method.

FIG. 14 is a diagram illustrating an example of a transmission / reception circuit of a differential FSK partial response system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 FSK modulation circuit 11 transmission antenna 12 reception antenna 20 transmission frequency conversion circuit 30 reception frequency conversion circuit 41 IF band demodulation circuit 42 IF band demodulation circuit 43 addition means 44 code reproduction circuit

Claims (6)

[Claims] An FSK modulation circuit that receives data input and converts the data into an intermediate frequency; transmission frequency conversion means that mixes an output of the modulation circuit with an output carrier of a local oscillation circuit and converts the output into upper and lower side waves; At least one transmitting antenna for wirelessly transmitting the output of the frequency conversion means, and at least one transmitting antenna for receiving a wireless signal from the transmitting antenna
Receiving antennas; receiving frequency converting means for receiving the outputs of the receiving antennas, separating the signals into intermediate frequency bands corresponding to the received upper and lower sideband signals, and frequency-converting them; A millimeter-wave FSK transmission / reception system comprising: an IF band demodulation circuit independently provided for receiving and demodulating to an original signal; and an adding means for adding an output of the IF band demodulation circuit. 2. The transmission antenna transmits linearly or circularly polarized waves with one transmitting antenna, and receives the linearly or circularly polarized waves as the transmitting wave with one receiving antenna. 2. The millimeter wave FSK transmission / reception system according to 1. 3. An antenna that transmits an upper band wave and two antennas that transmit a lower band wave are used as the transmitting antennas. The antenna transmits linearly polarized waves or circularly polarized waves from these antennas. The millimeter wave FSK transmission / reception system according to claim 1, wherein the wave or the circularly polarized wave is received by one reception antenna. 4. An antenna for transmitting linearly polarized light or circularly polarized wave with one transmitting antenna and transmitting an upper band wave and an antenna for transmitting lower linear wave as the transmitted wave. 2. The millimeter wave FSK transmission / reception system according to claim 1, wherein the reception is performed by two reception antennas. 5. The transmission code conversion unit according to claim 1, wherein a transmission code format from the transmission frequency conversion unit is a bipolar code, a Manchester code, a CMI code, or a zero continuous suppression code. Millimeter wave FSK transmission / reception system. 6. In a case where a combined signal of two baseband signals corresponding to the upper and lower sidebands is added by the adding means, and the result of the addition is identified by a code reproducing circuit that identifies the reference level, 6. The millimeter wave FSK transmission / reception system according to claim 5, wherein a comparison reference signal correction unit for correcting the identification level is provided at an input unit of the code reproduction circuit.