JPH0697907A - Spread spectrum demodulating equipment - Google Patents

Abstract

PURPOSE:To execute a stable operation in high speed synchronization and low C/N, and to simplify the equipment configuration by forming a circuit configuration which does not use a delay lock loop in the spread spectrum demodulating equipment. CONSTITUTION:A receiving spectrum signal 1 from a distributor 3 is converted to a base band zone by a local oscillator 6 and a mixer 5, passes through a low-pass filter 7, a both wave rectifying circuit 8 and a band pass filter 9, and a spread clock component is extracted. Also, an extracted clock is subjected to phase alignment so as to become optimal at the time of reverse spread demodulation by a phase deviator 10, passes through a sweep control AND gate 11, and is supplied to a PN generator 12. The other output of the distributor 3 goes into a mixer 13, is subjected to reverse spread to a signal from the PN generator 12, and demodulated at the time when a PN codes coincides. Subsequently, the demodulated signal is eliminated as to its noise by a band pass filter 14, and supplied to a PSL demodulating equipment 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum demodulation device having an improved PN pattern synchronizing means for inverse spread demodulation of a spread spectrum signal.

[0002]

2. Description of the Related Art As shown in FIG. 2, the structure of a conventional spread spectrum demodulator is as follows.
With the voltage controlled gain amplifier 2, the divider 21, and the detector 4,
After keeping the electric power of the entire received signal constant, the other side of the distributor 21 enters the distributor 22 and is branched into three. The distributor 22 and the output are respectively supplied to the next mixers 23, 24 and 25, where they are despread by the signal from the pN generator 26 and the spread signal is demodulated. The PN despread signals from the PN generator 26 are out of phase by Δ / 2. Note that Δ represents one clock of the spread clock. The demodulated signals from the mixers 23, 24, 25 have processing gains obtained by the following band pass filters 27, 28, 29, and are detected by the detectors 30, 31, 32 at the next stage,
It is input to the low pass filters 33, 34 and 35. The outputs of the low-pass filters 34 and 35 pass through a differencer 36, a loop filter 37, a voltage controlled oscillator (VCO) 38, an AND gate 39, and are fed back to the PN generator 26 to form a delay locked loop. ing. The outputs of the low-pass filters 34, 35, 36 are input to the decision units 40, 41, 42, and when the received signal is demodulated by despreading here, the polarities of the outputs of the decision units 40, 41, 42 are obtained. Is inverted and informs the next synchronization detector 43 that despread demodulation has been performed. The synchronous detector 43 sends a sweep stop signal to the sweep controller 44 when the despread demodulation is input from any of the determiners 40, 41, and 42. When the synchronization is not established, the sweep signal is sent from the sweep controller 44 to the AND gate 39. That is, a signal for periodically deleting one clock from the VCO 38 is transmitted, and this causes the PN diffusion speeds of the output of the AND gate 39 and the reception signal 1 to be different, so that sweeping can be performed digitally. become. When synchronization is established, PSK is output to the mixer 23 output.
The signal is demodulated, this signal is supplied to the PSK demodulator 102, and the data is demodulated.

[0003]

Since this conventional spread spectrum demodulation device forms a delay locked loop, the loop band is narrowed in order to enable operation even in a low C / N state. However, there is a drawback that it takes a lot of time to pull in.

[0004]

A spread spectrum demodulation device of the present invention receives a spread spectrum signal obtained by spreading a PSK modulated information signal by an integer multiple using a pseudo noise code, and outputs the PSK modulated information. In a spread spectrum demodulation device having a pseudo-noise generator for despreading demodulation for outputting a signal, and a sweep controller for synchronizing when a clock for spreading on the transmission side and a clock of the pseudo-noise generator are asynchronous , A distributor for distributing the output of the voltage gain control amplifier which makes the sum of the received spread spectrum signal and noise power constant, a local oscillator for converting one signal of the distributor to a baseband, and this local oscillator. Of the output signal of the distributor and the output signal of the distributor to output a baseband signal, and the output signal of the first mixer is input and sent. , A second mixer for inputting the other output signal of the distributed sound and the signal of the pseudo noise generator and outputting a despread demodulation signal, and a second clock of the second mixer. When it is determined that the output signal is not subjected to despread demodulation, there is provided a synchronization control means for controlling so that the clock output from the spread clock extraction means is deleted by one clock at an arbitrary cycle.

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention.

Next, the configuration and operation of the embodiment shown in FIG. 1 will be described. The received spread spectrum signal 1 is subjected to voltage gain control by the voltage control gain amplifier 2, the distributor 3 and the detector 4, and is controlled so that the sum of the received spread spectrum signal 1 and noise power becomes constant. The other output signal of the distributor 3 is converted into a baseband band by the local oscillator 6 and the mixer 5, and an unnecessary component is removed by the next low-pass filter 7. The output of the low-pass filter 7 is the following double-wave rectifier circuit 8,
Further, the spread clock component is supplied to the band pass filter 9, and the spread clock component is extracted from the received spread spectrum signal. The extracted clock is phase-matched by the phase shifter 10 so as to be optimum at the time of despread demodulation. This phase shifter 10
The output clock of is passed through the sweep control AND gate 11 and is supplied to the PN generator 12. The other output of the distributor 3 enters the mixer 13, is despread with the signal from the PN generator 12, and is demodulated when the PN codes match.
The demodulated signal is noise-removed by the bandpass filter 14, and one of them is divided by the distributor 15 into the PSK demodulator 102.
And the other is supplied to the detector 16. The output of the detector 16 determines whether or not despread demodulation is performed by the determiner 18 after the unnecessary components are removed by the low-pass filter 17, and the determination signal is passed to the next sweep controller 19. If the despreading demodulation is not performed, the sweep controller 19 sends a signal to the AND gate 11 so as to delete the clock for the PN generator 12 by one clock at an arbitrary cycle. As a result, the phases of the PN code of the received spread spectrum signal 1 and the PN code from the PN generator 12 are matched. When the phases match, the signal from the determiner 18 is output to the sweep controller 1
9 is input to the AND gate 11, and the AND gate 11 outputs a signal for preventing clock deletion. In this way, the spread spectrum signal is demodulated, and then the PSK demodulator 102 performs PSK demodulation.

[0007]

As described above, since the present invention does not use the delay lock loop used in the conventional spread spectrum demodulation device, the pull-in time is shortened even under the condition that the C / N is extremely bad. effective. Further, there is an effect that the device configuration can be greatly simplified.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional spread spectrum demodulation device.

[Explanation of symbols]

 1 Reception spread spectrum signal 2 Voltage gain control amplifier 3,15 Divider 4,16 Detector 5,13 Mixer 6 Local oscillator 7,17 Low pass filter 8 Double wave rectifier circuit 9,14 Band pass filter 10 Phase shifter 11 AND gate 12 PN generator 14 Bandpass filter 18 Judgmenter 19 Sweep controller 100, 101 Spread spectrum demodulator 102 PSK demodulator

Claims (2)

[Claims] 1. A pseudo noise generator for despread demodulation, which receives a spread spectrum signal obtained by spreading an integer multiple of a PSK modulated information signal using a pseudo noise code and outputs the PSK modulated information signal. And a spread spectrum demodulating device having a sweep controller for synchronizing the spread clock on the transmission side and the clock of the pseudo noise generator when they are asynchronous, the sum of the spread spectrum signal and the noise power received A distributor for distributing the output of the voltage gain control amplifier to be constant, a local oscillator for converting one signal of the distributor to a baseband, and an input of the output of the local oscillator and the output signal of the distributor. A first mixer for outputting a baseband signal as a baseband signal, and a spread clock extracting means for receiving an output signal of the first mixer and extracting a clock signal on the sending side, A second mixer which inputs the other output signal of the distributed sound and the signal of the pseudo noise generator and outputs a despread demodulation signal, and it is determined that the output signal of the second mixer is not despread demodulated. In this case, there is provided a spread spectrum demodulation device comprising: a synchronization control means for controlling the clock output from the spread clock extraction means so as to delete one clock at an arbitrary cycle. 2. The control signal output by controlling the sweep controller and the spread clock extraction means when the synchronization control means inputs the output signal of the second mixer and determines that despread demodulation is not performed. 2. The spread spectrum demodulation device according to claim 1, wherein the pseudo noise generator is controlled by inputting the output clock of the above and the logical product of the outputs.