Abstract: A video data link system utilizes spread spectrum to decrease the susceptlity of a low power video link to radio frequency countermeasures. The video data link system utilizes a combination of spread spectrum direct-sequence modulation and frequency-hop along with frequency modulation to provide spectral spreading of radio frequency energy to a bandwidth much greater than the information bandwidth. The direct sequence modulation allows minimization of the number of frequency steps required for complete spectral filling of the operational bandwidth on an average basis. Frequency hop timing is determined from the phase of the direct sequence generator to simplify the frequency hop synchronization process in the receiver. Bandwidth of the fm video signal, after being spread in spectral width by the bi-phase direct sequence signal, is approximately equal to the direct pseudo random sequence clock rate.

Abstract: This is a method of waveform design and range correlator implementation t uses weighting to optimize a radar receiver's ambiguity response in both the temporal and frequency dimensions of the ambiguity function. It is an extension of group-complementary code structure and is based on a multipulse processing technique.The procedure minimizes frequency sidelobes over a selected interval in the spectral domain between dc and the pulse repetition frequency and completely eliminates temporal sidelobes throughout the pulse repetition interval. It minimizes clutter and multitarget interference in an active-sensor target acquisition and tracking application, and still allows weighting of the pulse responses to reduce frequency domain sidelobes.

Abstract: A group-complementary codes provide sets of binary word groups which have the combined properties of optimized aperiodic autocorrelation and optimized cross-correlation between word sets. The optimized aperiodic autocorrelation property allows the implementation of pulse compression processing in sensor systems to achieve zero value temporal or range sidelobes within the principal interpulse period without resorting to weighting techniques for sidelobe reduction. The orthogonal nature of group-complementary codes, apparent from their absence of cross-correlation between sets, allows sensors to be deployed in close proximity, using the same carrier frequency without direct path mutual interference when synchronized.

Abstract: This concept makes use of the orthogonal nature of Group-Complementary Co to achieve improved polarization isolation between the vertical and horizontal radiation in a circularly polarized or dual linearly polarized antenna system while achieving zero time-sidelobe responses in pulse compression. Two channels of a radar system are established with each being encoded using an orthogonal Group-Complementary Code. One channel is associated with the vertical polarization of radiation while the second is devoted to the horizontal polarization. With a leading or lagging 90 degree phase relationship between the two channels, right hand or left hand circular polarization can be established according to the code of each channel which controls the relative phase. Such a technique of pulse compression and group complementary coding offers improved polarization isolation between channels while achieving zero-time sidelobes in pulse compression.