US 5,347,537 A · Spread spectrum communication device

Abstract

In a spread spectrum communication system for communicating data by spreading spectrum, thereof, using PN codes, on the transmitter side, a first modulated output portion, which is spread-spectrum-modulated, containing no data to be transmitted and a second modulated output portion, which is spread-spectrum-modulated, following the first modulated output portion and containing data to be transmitted are generated; and the second modulated output portion is transmitted with a low electric power and the first modulated output portion with a high electric power. On the receiver side, a correlation-demodulated output is generated by correlation-demodulating a received input; and from the correlation-demodulated output consisting of a first correlation-demodulated output portion corresponding to the first modulated output portion and a second correlation-demodulated output portion corresponding to the second modulated output portion the first correlation-demodulated output portion is detected. Further timing signal serving as a reference for an operation on the receiver side is generated, starting from the first correlation-demodulated output portion.

Claims4

Dependent claims

A spread spectrum communication method for communicating data by spreading the spectrum thereof, using PN codes, comprising:

`A. on the transmitter side,
a) a step of generating a spread-spectrum-modulated output consisting of a first modulated output portion, which is spread-spectrum-modulated, and a second modulated output portion, which is spread-spectrum-modulated, following said first modulated output portion;
and
b) a step of transmitting said spread-spectrum-modulated output so as to transmit said second modulated output portion with a low electric power and said first modulated output portion with a high electric power;
and
B. on the receiver side,
a) a step of setting a gain in a path from reception to generation of the correlation-modulated output of said received input at a low level;
b) a step of detecting from said correlation-demodulated output consisting of a first correlation-demodulated output portion corresponding to said first modulated output portion and a second correlation-demodulated output portion corresponding to said second modulated output portion an end of said first correlation-demodulated output portion;
and
c) a step of setting the gain in said path at a high level at the detecting of the end.

7 more elements

A spread spectrum communication device for communicating data by spreading the spectrum thereof, using PN codes, consisting of:

A. a transmitter comprising:
a) period specifying means for determining a packet period consisting of a burst period and a data period following said burst period, in order to transmit data;
b) PN code train generating means for generating a PN code train consisting of a repetition of first PN codes with a predetermined period;
c) modulating signal generating means for generating a modulating signal consisting of said data to be transmitted during said data period, containing no data during said burst period;
d) spread-spectrum-modulating means for generating a spread-spectrum-modulated output by spread-spectrum-modulating said PN code train with said modulating signal;
e) transmission power specifying means for generating a transmission power specifying signal for specifying a high transmission power during said burst period and a low transmission power during said data period;
and
f) transmitting means for transmitting said spread-spectrum-modulated output with an electric power corresponding to said transmission power specifying signal;
and
B. a receiver comprising:
a) frequency-converting means for obtaining a frequency-converted output by frequency-converting a received input;
b) correlator means for generating a correlation output from said frequency-converted output by using a PN code train consisting of a repetition of second PN codes inverted in time with respect to said first PN codes;
c) burst detecting means which compares said correlation output with a predetermined threshold and, when said correlation output is greater than said predetermined threshold, generates a timing signal expressing it, said predetermined threshold being lower than a level of said correlation output during said burst period, but higher than the level of said correlation output during said data period;
and
d) gain specifying means for specifying a signal gain either in said frequency-converting means or in said correlator means, which specifies a low gain, before said timing signal is received, and a high gain in a duration longer than said data duration, after said timing signal has been received.

12 more elements

Dependencies are inferred from the claim text.

Spread spectrum communication device

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Spread spectrum communication device

Life of this patent

Abstract

Claims4