Low-complexity direct conversion receiver for delay-and-correlate transmitted reference signaling
First Claim
1. A direct conversion receiver for delay-and-correlate transmitted reference spread spectrum signaling, comprising:
- means for converting a received direct sequence spread spectrum signal having a predetermined chipping rate to a baseband signal;
an analog-to-digital converter for sampling the baseband signal at a rate greater than the chipping rate of the direct sequence spread spectrum signal;
delay means coupled to the analog-to-digital converter output for generating a delayed signal;
multiplier logic for receiving output signals from said analog-to-digital converter and said delay means and for generating control output signals; and
a counter responsive to said control output signals for incrementing or decrementing a count or recycling.
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Abstract
A direct conversion receiver for a delay-and-correlate transmitted reference spread spectrum signaling method and apparatus is based on minimal component digital circuitry instead of analog delay and multiplier circuits. The method allows direct RF to baseband conversion and eliminates the need for an IF stage. The receiver includes an RF converter for converting a received direct sequence spread spectrum signal to baseband. An analog-to-digital converter samples the baseband signal at a rate greater than the chipping rate of the direct sequence spread spectrum signal. A delay stage coupled to the output of the analog-to-digital converter generates a delayed signal. Multiplier logic receives output signals from the analog-to-digital converter and the delay stage and, in response, generates control output signals. A counter responsive to the control output signals increments or decrements a count or recycles, depending on the decoded control output signals.
64 Citations
12 Claims
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1. A direct conversion receiver for delay-and-correlate transmitted reference spread spectrum signaling, comprising:
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means for converting a received direct sequence spread spectrum signal having a predetermined chipping rate to a baseband signal; an analog-to-digital converter for sampling the baseband signal at a rate greater than the chipping rate of the direct sequence spread spectrum signal; delay means coupled to the analog-to-digital converter output for generating a delayed signal; multiplier logic for receiving output signals from said analog-to-digital converter and said delay means and for generating control output signals; and a counter responsive to said control output signals for incrementing or decrementing a count or recycling. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A delay-and-correlate transmitted reference spread spectrum communications system comprising:
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a transmitter including a sequence generator for generating a spreading signal, an Exclusive OR gate for receiving a data input and said spreading signal, a first delay means coupled to an output of the Exclusive OR gate for generating a first delayed signal, a summer for combining said spreading signal with said first delayed signal, and an RF transmitter for transmitting a combined output signal from the summer; and a receiver including means for converting a received direct sequence spread spectrum signal having a predetermined chipping rate to a baseband signal, an analog-to-digital converter for sampling the baseband signal at a rate greater than said chipping rate, a second delay means coupled to the output of the analog-to-digital converter for generating a delayed signal, multiplier logic for receiving output signals from said analog-to-digital converter and said second delay means and for generating control output signals, and a counter responsive to said control output signals for incrementing or decrementing a count or recycling. - View Dependent Claims (11, 12)
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Specification