JP3223900B2 - Burst spread spectrum communication receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to burst spread spectrum communication (hereinafter, also referred to as "burst SS communication"), and in particular, enables switching between transmission signals of transmission apparatuses using different spreading codes to enable handover of transmission data. The present invention relates to a burst SS communication receiver that can prevent loss.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing an outline of a configuration of a transmission / reception system using a conventional burst SS communication. Transmitting device 1 and transmitting device 2 having different spreading codes
And a receiver 3 that can set two spreading codes for receiving respective radio waves transmitted by the transmitting devices 1 and 2 and demodulating data.

[0005] The receiver 3 is configured to selectively switch and use the spreading code used in the transmitting device when the transmitting device 1 or 2 is switched, and demodulate.

FIG. 9 is a diagram showing the transmission timing of a burst transmission signal of the transmission device 1 and the transmission device 2. In FIG. 8, a transmission apparatus 1 and a transmission apparatus 2 respectively modulate a carrier with transmission data, such as phase shift keying (PSK), and transmit data in a burst. The high-level period of the pulse shown in FIG. 9 is a period during which a burst data signal is transmitted. The transmission timing of the transmission signal from each of the transmission devices 1 and 2 is such that SS (DS: direct spreading method) transmission is performed at a period of time t, and the two transmission devices perform a synchronous transmission operation as shown in FIG. Do. By performing such a synchronous operation, it is possible for the receiver 3 to perform demodulation without generating data loss from the time of switching at the time of switching reception of transmission signals from the transmitting devices 1 and 2.

[0005]

In the conventional transmission / reception system of the burst SS communication as described above, two transmission devices operate in synchronization with each other in data period and operate synchronously to transmit a transmission wave. If possible, when the transmission signals of the transmission devices are switched with each other, and when the signals from the transmission devices are switched and received, the receiver switches the reception code at the switching timing, so that the data is not lost at the time of switching. It is possible to receive and demodulate data.

However, when the operations of the transmission devices 1 and 2 are independent of each other and the burst SS transmission is performed asynchronously, it is difficult to avoid a situation in which data is lost when the transmission devices are switched. That is, in the conventional burst SS communication receiver, when the transmission data from the transmission devices 1 and 2 is switched and received, or the like, the data is lost while the data of the transmission device after the switching can be normally received. Was unavoidable.

Further, in a transmission / reception system having a plurality of transmission devices for performing such asynchronous transmission, if loss of data at the time of switching is not allowed, a frequency multiplexing technique is used, and two receivers are used on the receiving side. It is necessary to adopt a method of discriminating frequencies and receiving each of them to switch reception, but adopting such a system is a waste of frequency, which is a finite resource, and an increase in cost due to the use of multiple receivers. There was a problem in that it occurred.

(Object of the Invention) It is an object of the present invention to provide a burst SS communication receiver capable of eliminating data loss that occurs at the time of switching between transmission devices in burst SS communication or when switching received signals from a plurality of transmission devices. Is to do.

An object of the present invention is to provide a burst SS communication receiver capable of selecting a transmission device to be received in burst SS communication without data loss.

[0010]

SUMMARY OF THE INVENTION A burst spread spectrum communication receiver according to the present invention is a burst spread spectrum communication receiver for receiving a burst transmission signal by spread spectrum of different spreading codes transmitted from a plurality of transmitting devices. A receiving unit that receives transmission signals from the plurality of transmitting devices, a code generator that generates the same spreading code as a spreading code used in the transmitting device, and an output of the code generator and an output of the receiving unit. An initial synchronization correlator that establishes synchronization between the spread code of the code generator and the spread code of the transmitting device by performing a correlation process, and performs an integration process on the output of the code generator and the output of the receiving unit to obtain data. A plurality of demodulation units each comprising a data demodulation unit for demodulation; and a spreading code for setting a spreading code to a code generator of the plurality of demodulation units. Has a de setting means, have a, an external interface unit that identifies a received signal from one or more transmitting devices to be received, and outputs the switching as input the output of the data demodulator by the spreading code setting unit
The initial synchronization correlating unit outputs the output of the receiving unit and the
The correlation value in code length units with the output of the
The output phase of the code generator is controlled so as to exceed the threshold.
And one of the plurality of demodulation units is an AGC feedback
Output a voltage and perform AGC control of the receiving unit.
In addition, a plurality of demodulation units are provided by the AGC feedback voltage.
The threshold value is controlled .

(Operation) Burst S from a plurality of transmitting devices
The configuration using one reception unit and a plurality of demodulation units enables switching reception of the S signal by an external bus interface without causing data loss. By setting different spreading codes to a plurality of demodulation units, demodulated data is switched and output according to the characteristics of SS communication.
In the initial synchronization operation of the spread code, the synchronization is determined based on the magnitude of the correlation value. The AGC voltage from one demodulation unit controls the AGC of the reception unit and also controls the determination level of the correlation value for synchronization determination of all demodulation units.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a burst SS communication receiver capable of taking over according to the present invention will be described with reference to the drawings. In the present embodiment, the basic configuration of the transmission / reception system adopts the above-described configuration shown in FIG. 1, and an example will be described in which the transmission devices 1 and 2 perform a transmission operation that is asynchronous with each other. FIG. 1 is a diagram showing a configuration of a receiver according to an embodiment of a burst SS communication receiver capable of taking over according to the present invention. A receiver 4 for converting a signal received through an antenna into a received signal having a residual carrier (beat), two demodulators 5 for establishing initial synchronization with the received signal, despreading the received signal and demodulating data; The demodulation unit 6 includes an external bus interface unit 6 that interfaces with the outside.

The receiving section 4 includes a mixer 41 for multiplying a signal from the antenna by an output of the first crystal oscillator and converting the signal to an intermediate frequency signal, intermediate frequency amplifiers 42 and 43 for performing AGC amplification of the intermediate frequency signal, The intermediate frequency amplifier 42,
A mixer 4 which multiplies the output of the second output 43 by an output having a quadrature-phase relationship with the output of the second crystal oscillator by a phase shifter 45 and outputs received signals Ich and Qch as components of a quadrature axis.
4, 45, and an A / D converter for digitizing the received signals Ich and Qch.

The demodulation units 5 and 6 are provided for performing respective demodulation processes on the digitized reception signals (hereinafter simply referred to as “reception signals”) from the two transmission devices. The outline of the configuration of the demodulation units 5 and 6 includes a code generation unit that outputs the same spread code as two different spread codes used by the two transmission devices by the output of the crystal oscillator, and includes the reception signals Ich and Qch. An initial synchronization correlator for synchronizing the phase with the spread code from the code generator and outputting a feedback signal for AGC control to the intermediate frequency amplifiers 42 and 43; and It comprises a demodulator / controller for reproducing the residual carrier from the received signal and demodulating / controlling the data.

The external bus interface unit 7 includes a means for outputting demodulated data to the external bus, and a code generation unit 55 for receiving and demodulating transmission signals from the transmission devices 1 and 2.
It has a configuration of a setting unit that can set a PN code for the 65. Also, by setting the PN code,
It is possible to specify one or a plurality of transmission devices to be received and to substantially switch output data of the demodulation unit.

FIG. 2 is a block diagram showing a more detailed configuration of the demodulation units 5 and 6. In the present embodiment, the demodulator 5,
Reference numeral 6 denotes correlators 51 and 61 and synchronization determination units 52 and 62 that constitute an initial synchronization correlation unit, integrators 53 and 63 and data demodulation units 54 and 64 that constitute a demodulation / control unit, and a synchronization determination unit And control units 57 and 6 for controlling the data demodulation unit
7; code generators 55 and 65 for generating PN codes used in the two transmitting devices; and crystal oscillators 56 and 66 for outputting clocks for generating the codes. The function of each section of the demodulation sections 5 and 6 is outlined below.

The correlators 51 and 61 receive the received signals Ich and Q
This is a correlator having a phase shifter for adjusting the phase of the residual carrier wave (beat) of the channel, performs a correlation operation with the PN code and outputs a correlation value, and the phase shifter outputs the AGC feedback voltage.

The synchronization judging sections 52 and 62 output the received signal I
Correlation calculation is performed on the ch and Qch and the PN code and the code in which the phase is sequentially shifted in units of one clock, and phase information that matches the phase with the PN code is detected and output from the correlation value.

The integrators 53 and 63 are integrators having a phase adjuster for adjusting the phase of the residual carrier (beat) of the received signals Ich and Qch, and are based on the phase information output by the synchronization determination units 52 and 62. The code holding control is performed, and the correct phase P output from the code generators 55 and 65 is output.
The despreading operation of the received signals Ich and Qch is performed by the N code.

The data demodulators 54 and 64 receive the despread operation outputs of the received signals Ich and Qch, reproduce the residual carrier signal, demodulate the data from the transmitter, and output the data. Control of the code generator based on the code generation.

FIG. 3 is a diagram showing a more detailed configuration of the correlator 51. As shown in FIG. The correlator 51 receives the received signals Ich and Qch
A phase shifter 511 which adjusts the phase of the phase shifter and outputs an AGC feedback voltage having a detection function;
Shift registers 512 and 513 that serially shift the output of the
5 includes shift registers 514 and 515 for serially shifting the PN code from 5, adders 516 and 517, and an arithmetic unit 519. In the correlator 51, the adder 516 uses the multiplier 518 and the adder to control the reception signal Ich.
The sum ΣI of the sum of the multiplied values of the outputs of the respective stages of the shift registers 512 and 513 is output, and the adder 517 outputs the reception signal Qch
The sum ΣQ of the sum of the multiplied values of the outputs of the respective stages of the respective shift registers 513 and 515 is output.
(ΣI ² + ΣQ ² ) of both sums ΣI and と し て Q as correlation values
^1/2 are calculated and output. The correlator 61 also has substantially the same configuration and function as the correlator 51, but differs in the present embodiment in that the AGC feedback voltage is configured to be input from the demodulator 5 side.

FIG. 4 is a diagram showing a more detailed configuration of the integrator 53. The integrator 53 receives the received signals Ich and Qch
, A shift register 532, 533 for serially shifting the output of the phase shifter 531 in clock units, and a shift register 5 for serially shifting the PN code from the code generator 55.
34, 535 and adders 536, 537. In the accumulator 53, the adder 536 is used as a multiplier 538.
And the adder outputs the sum ΣI of the sum of the multiplied values of the outputs of the respective shift registers 512 and 513 on the reception signal Ich side, and the adder 517 outputs the multiplier 518
And the adder outputs the sum ΣQ of the sum output of the multiplied values of the outputs of the respective shift registers 533 and 535 on the reception signal Qch side as the despread output of the reception signal. Integrator 6
3 also has substantially the same configuration and function as the integrator 53.

FIG. 5 is a diagram showing a more specific configuration of the synchronization determination section 52. The synchronization determination unit 52 controls the code generator and calculates the correlation value ({I ² +}) calculated and output from the correlator 51 in units of n bits, which is the code length unit of the PN code.
Q ² ) ^1/2 is shifted the phase of the PN code by one clock unit to n storage locations 521, 522,... 52n corresponding to the phase of the spread code, and the correlation value (ΣI ²
+ ΣQ ² ) has a storage unit for storing ^{１ ／} , determines the correct phase of the PN code by comparing the stored correlation value with a predetermined threshold value, and outputs phase information when synchronization is achieved. . That is, the output from the correlator 51 is stored in the memory in the order of phases, the threshold value is adjusted by the input AGC feedback voltage, and stored (ΣI ² + ΣQ ² ) ^1/2
The data which exceeds the threshold value is found out of the data of (1), and the output phase of the code generator is controlled to the phase. The synchronization determination unit 62 also has substantially the same configuration and function as the synchronization determination unit 52, and the AGC feedback voltage required for this is input from the demodulation unit 5.

Next, the operation of the burst spread spectrum communication receiver according to the present embodiment will be described for the case where transmitting apparatuses 1 and 2 perform asynchronous transmission operations. FIG. 6 is a diagram illustrating an example of the transmission timing of the burst SS signal of each transmission device when the transmission devices 1 and 2 perform an asynchronous transmission operation. In the example shown in FIG. 6, the transmission timings of the transmission device 1 and the transmission device 2 are such that the period between burst signals is time t, and the phase of the burst is shifted by time t1.

FIG. 7 is a diagram showing a correlation value output in the synchronization determination section. Ich / Q in receiving section 4 shown in FIG.
The received signals decomposed into channels are demodulated by demodulation units 5 and 6 shown in FIG.
Are input to the correlators 51 and 61. The correlators 51, 6
1 includes code generators 55 and 65 for generating the same spreading codes as the respective spreading codes of the transmitters 1 and 2 set from the external bus interface unit, and each of the n clocks having a different phase every clock. Correlation values between the spread code in units of (one code length) and the received signal are calculated, and the results are output to the synchronization determination units 52 and 62. When the correlation value between the spread code in units of n clocks (one code length) and the received signal is calculated, the synchronization determination units 52 and 62 control the data demodulation units 54 and 64 and generate codes from the data demodulation units 54 and 64. The correlation processing operation of the correlators 51 and 61 is repeated by changing the code phase of the coders 55 and 65 by one clock, and the result is output to the synchronization determination units 52 and 62. Similarly, a correlation value of n clocks (one code length) having a different phase for each clock is obtained, and the integration result for each spread code phase is stored as a correlation value in the storage units of the synchronization determination units 52 and 62. Is done.

FIG. 7 shows the timings A to A ′, B to
It is a figure which shows the correlation value of the integration result in the synchronization determination part in B ', C-C', and D-D '. FIG. 7A shows the time A to
7A shows correlation values in the synchronization determination unit 52 for A ′ and C to C ′, and FIG. 7B shows correlation values in the synchronization determination unit 62 for times A to A ′ and C to C ′. Also,
FIG. 7C shows correlation values in the synchronization determination unit 52 at times B to B ′ and D to D ′, and FIG.
13 shows correlation values in the synchronization determination unit 62 for B ′ and D ′ to D ′.

Each of the correlation values and the synchronization judgment unit 52 shown in FIG.
A predetermined threshold value determined by the average value and the maximum value of the correlation values of 62 is controlled by an AGC feedback voltage input from the phase shifter 511 and output from the synchronization determination units 52 and 62 to determine the data. The code generators 55 and 65 are controlled via the demodulators 54 and 64, and the phase of the spread code output from the code generators 55 and 65 is obtained. The code holding control is performed by the control units 57 and 67 so that the code holding is performed.

Next, the received signal is subjected to despreading processing of spread spectrum in the integrators 53 and 63, and the data is demodulated by reproducing the residual carrier component in the data demodulators 54 and 64. Is output.

In the above operation, the correlators 51 to the control unit 57 of FIG. 2 operate at the transmission timings A to A ′ and C to C ′ shown in FIG. The data is demodulated and output. In addition, at times B to B ′ of the transmission timing shown in FIG. 6 when the burst signal of the transmitting device 2 is received, the correlators 61 to the control unit 67 of FIG. 2 operate to demodulate and output data. Therefore, at times B to A ′ and D to C ′ of the transmission timing at which the transmission devices 1 and 2 transmit any burst signal, the correlator 51 is not used.
The control unit 67 operates to demodulate and output both data. Therefore, the external bus interface unit 7 can switch output data from a desired demodulation unit and output the data to the bus.

As described above, in the present embodiment, even in a period in which two waves are simultaneously mixed, the characteristics of the burst signal by the spread spectrum are utilized, so that one receiver can transmit the transmission signals from the two transmission devices. Demodulation can be performed, and switching output can be performed without any loss of transmission data.

In the above-described embodiment, a case has been described where two transmission devices are used as transmission sides of burst spread spectrum communication in which transmission data is transmitted in a burst form by spread spectrum. It goes without saying that a plurality of the above configurations can be adopted. Further, the burst periods of the burst transmission signals transmitted by the plurality of transmission devices and the mutual phase relationship can be configured to perform different operations.

The switching of the transmission device may be performed by turning on / off the transmission signal on the transmission device side.
It is apparent that the demodulation output can be switched by the external bus interface unit on the receiver side, and that the switching can also be performed by setting the spreading code to the code generator from the external bus interface unit.

In this embodiment, an example in which the phase shift keying method is adopted as the modulation method has been described, but it goes without saying that other modulation methods can be adopted.

[0034]

According to the present invention, since demodulators corresponding to a plurality of different spreading codes are prepared, data can be arbitrarily switched between two asynchronously transmitted transmitters without causing any loss. Data can be demodulated and output.

The setting of the spreading code from the external interface unit to the plurality of demodulation units makes it possible to specify the transmission device to be received.

Each demodulation unit is provided with a dedicated initial synchronization correlating unit.
Since it is possible to constantly monitor the / OFF state, it is possible to quickly grasp the communication state.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a demodulation unit and an external interface unit according to the present embodiment.

FIG. 3 is a diagram illustrating a configuration of a correlator according to the present embodiment.

FIG. 4 is a diagram illustrating an outline of a configuration of a synchronization determination unit according to the present embodiment.

FIG. 5 is a diagram showing a configuration of an integrator according to the present embodiment.

FIG. 6 is a diagram illustrating a transmission timing by an asynchronous operation of the transmission device of the present embodiment.

FIG. 7 is a diagram illustrating a correlation process in a synchronization determination unit according to the present embodiment.

FIG. 8 is a diagram showing a conventional basic system for transmitting and receiving burst SS communication.

FIG. 9 is a diagram illustrating transmission timing of a transmission device in conventional burst SS communication.

[Explanation of symbols]

 1, 2 transmitter 3 receiver 4 receiver 5, 6 demodulator 7 external bus interface 41, 44, 45 mixer 42, 43 intermediate frequency amplifier (AGC amplification) 51, 61 correlator 52, 62 synchronization determiner 54, 64 Data demodulation unit 55, 65 Code generator 56, 66 Crystal oscillator 57, 67 Control unit 511 Phase shifter 512-515, 532-535 Shift register 516, 517, 536, 537 Adder 519 Operation unit 531 Correlator 538 Multiplier

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/69-1/713 H04J 13/00-13/06 H04B 1/16

Claims (1)

(57) [Claims] 1. A burst spread spectrum communication receiver for receiving a burst-like transmission signal by spread spectrum of different spreading codes transmitted from a plurality of transmission devices, a receiving unit receiving transmission signals from the plurality of transmission devices. And a code generator for generating the same spreading code as the spreading code used in the transmitting device, and performing a correlation process between the output of the code generator and the output of the receiving unit to obtain the spreading code of the code generator. An initial synchronization correlator that establishes synchronization with the spread code of the transmitting device, and a plurality of demodulators including a data demodulator that demodulates data by performing an integration process on the output of the code generator and the output of the receiver, A spreading code setting means for setting a spreading code for a code generator of a plurality of demodulation units; Or identify the received signals from a plurality of transmitting apparatuses have an external interface unit that outputs switch receives the output of the data demodulator, the initial synchronization correlator unit, the code the output of the receiving section
The correlation value of the code length unit with the output of the generator is a predetermined threshold.
Control the output phase of the code generator to exceed the value
One of the plurality of demodulation units is an AGC feedback power supply.
Output the pressure and perform AGC control of the receiving unit.
Before the plurality of demodulation units by the AGC feedback voltage
A burst spread spectrum communication receiver characterized by controlling the threshold value .