Abstract: A radar system (22) includes a transmitter (45), a receiver (59), and a software defined radio (SDR) peripheral (40). Methodology (80) for investigating a target zone (26) utilizing the system (22) entails generating (106) a direct sequence spread spectrum (DSSS) code (120) having a code length (122) corresponding to a time duration of radio wave travel between the transmitter (45), the target zone (26), and the receiver (59) at a carrier frequency (112). A beacon signal (34), modulated (108) by the DSSS code (120), is transmitted (152) from the transmitter (45) toward the target zone (26) and a return signal (38) is received (156) at the receiver (56). The return signal (38) is compared (170) to a replica signal (168) characterized by the DSSS code (120), and presence of an object (32) in the target zone (26) is ascertained (178) when the return signal (38) matches the replica signal (168).

Abstract: A method of wireless communication in a lossy environment entails generating a direct sequence spread spectrum (DSSS) code string that includes a pseudo-noise (PN) sequence followed by instances of shifted PN sequences, where the shifted PN sequences are produced in response to the content of the message. The PN sequence includes a plurality of chips arranged in a first order, and each of the shifted PN sequences includes the plurality of chips arranged in another order. A beacon signal modulated by the DSSS code string is transmitted from a transceiver and received at a receiver within the communication system. Correlation peaks are formed at the receiver, where each correlation peak is associated with one of the PN sequences or one of the shifted PN sequences. Shift values are determined from the correlation peaks and the shift values are decoded to produce the message at the receiver.

Abstract: A method of wireless communication in a lossy environment entails generating a direct sequence spread spectrum (DSSS) code string that includes a pseudo-noise (PN) sequence followed by instances of shifted PN sequences, where the shifted PN sequences are produced in response to the content of the message. The PN sequence includes a plurality of chips arranged in a first order, and each of the shifted PN sequences includes the plurality of chips arranged in another order. A beacon signal modulated by the DSSS code string is transmitted from a transceiver and received at a receiver within the communication system. Correlation peaks are formed at the receiver, where each correlation peak is associated with one of the PN sequences or one of the shifted PN sequences. Shift values are determined from the correlation peaks and the shift values are decoded to produce the message at the receiver.

Abstract: A radar system (22) includes a transmitter (45), a receiver (59), and a software defined radio (SDR) peripheral (40). Methodology (80) for investigating a target zone (26) utilizing the system (22) entails generating (106) a direct sequence spread spectrum (DSSS) code (120) having a code length (122) corresponding to a time duration of radio wave travel between the transmitter (45), the target zone (26), and the receiver (59) at a carrier frequency (112). A beacon signal (34), modulated (108) by the DSSS code (120), is transmitted (152) from the transmitter (45) toward the target zone (26) and a return signal (38) is received (156) at the receiver (56). The return signal (38) is compared (170) to a replica signal (168) characterized by the DSSS code (120), and presence of an object (32) in the target zone (26) is ascertained (178) when the return signal (38) matches the replica signal (168).

Abstract: An underwater location beacon emits a continuous wave signal which is phase-shift modulated by a pseudo-noise, spread spectrum code. This signal is detected with an exact replica of the transmitted code. To an unauthorized observer without the replica, the transponder's signal is indistinguishable from background ocean noise. The spread spectrum code allows extraction of the signal from high levels of ocean noise, providing an increased detection range, jamming resistance, covertness, and unique signals for each pinger. The outputs of the surface spread spectrum receiver are used with automated location algorithms. Several receivers at different surface positions provide the underwater coordinates of the pinger's location.