SAW correlator spread spectrum receiver
| DWPI Title: Apparatus for receiving spread-spectrum (SS) signal transmitted at radio-frequency (RF), receives bipolar electrical pulse signals at input and output, so that low frequency output signal is provided with information in decoded state |
| Abstract: A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n×m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals. |
| Use: Apparatus for receiving spread-spectrum (SS) signal transmitted at radio-frequency (RF) and recovering information coded in transmitted SS signal. |
| Advantage: The third SAW correlator provides low frequency output signal with information in decoded state, since the acoustic attenuation at the intermediate (IF) frequency is less than that at RF frequency. The longer codes are possible for the SS signal by using a broader bandwidth for the first and second SAW correlators. Thus, the IF frequency can be increased and the length of the third SAW correlator can be shortened. Hence, the larger chip length can be allowed for a given size substrate. The increase in impedance through the RF envelope detectors can allow for the increase in signal voltage. Since the SAW correlators are operated passively, the only electrical power required for the SAW correlator SS receiver is used in biasing the RF envelope detectors to reduce the loss. |
| Novelty: The apparatus (10) has first and second SAW correlators (16,18) that are provided with input that is operatively connected to an antenna (110) to receive SS signal (100). A detector (34) is connected to output of first and second correlators to rectify output of first and second correlators. A circuit (36) is connected to detectors to receive rectified output and to produce bipolar pulse signal. A third SAW correlator (20) receives bipolar electrical pulse signals at input and output, so that low frequency output signal is provided with information in decoded state. |
| Filed: 10/6/2005 |
| Application Number: US2005245358A |
| Tech ID: SD 7569.1 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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