Unisys Corporation

Richard J Saggio

John W Zscheile, Jr

Michael Wilson

Alan E Lundquist

Robert V Jones

Richard B Mouldin

Apparatus and method are provided for adaptively modulating or combining a first signal with a second signal. A series of values of the first signal are taken and sequentially stored in a shift register. The maximum absolute value of the oldest N values (where N is an integer) stored in the shift register is then determined. Before, during or after that determination, the maximum absolute value of the remaining (newer) series of values of the shift register is also determined. The lesser of those two maximum absolute values is then determined. This lesser maximum absolute value is then multiplied by a gain factor representing the desired gain to produce a scale factor. The gain factor can be a preset constant, or can be based on the steady-state ratio of the power of the second signal to the power of the first signal. The second signal is then multiplied by the scale factor to produce a scaled signal. Meanwhile, the first signal has been delayed by an amount representative of the total time duration of the first N values in the shift register, or of the total time needed to obtain those first N values, or of the duration of the portion of the signal represented by those first N values. Considering the two peaks separately, combined with using this delay, in effect enables the resulting amplitude tracking to consider prospective as well as past values of the first signal. The scaled signal is then added to the delayed first signal. The amplitude of the scaled second signal thereby tracks the amplitude of the corresponding portion of the first signal, so that the scaled second signal cannot be readily detected unaided during any relatively low amplitude portion of the first signal.

Apparatus and method for amplitude tracking

A novel code division multiple access (CDMA) system and apparatus is provided which permits a plurality of encoded modulated data messages to be transmitted simultaneously on the same channel in one frequency band as a composite CDMA signal. An identification signal is generated and spread by a spreading signal having a duty cycle less than fifty percent to produce a combined signal which is transmitted to a receiver having a tapped delay with a plurality of taps each of which produce a replica of the received combined signal delayed by an odd multiple of the duty cycle of the spreading signal. Each of the replica signals is multiplied by a predetermined weighted value to produce weighted delayed signals and a controller responsive to the received combined signal, is employed for controlling individual weighted delayed signals which are then combined to suppress the spreading signal leaving the identification signal.

Apparatus and method for signal identification

A set of independent pseudonoise (PN) component codes greater than two are combined in a manner which produces one or more I and Q uncorrelated orthogonal pairs of resulting combined PN sequences. At least two of the component codes in a resulting combined PN sequence are combined in a manner which produces an overall imbalance of ones and zeros in the binary expression of the resulting combined PN sequence so that the resulting composite code has a partial correlation with a predetermined one of the PN component codes. In the preferred embodiment, three component codes are combined to produce uncorrelated orthogonal pairs of composite codes wherein at least one of the pairs of composite codes is produced to have a partial correlation with one or more of the component codes.

Apparatus and method for generating and utilizing pseudonoise code

A transmitter is provided which simultaneously transmits waveforms such as with different data rates. These transmissions are modulated (e.g. phase modulated) onto quadrature channels of a common carrier, and are then combined. The resulting composite modulated waveform is upconverted to RF, power amplified, split and routed to separate ports for transmission. The transmitted signals are then received, downconverted and demodulated to produce the original signals.

Multiple channel quadrature communication system and method

An electronic identification system for use by vehicles on a battlefield comprises an interrogator circuit in an attack vehicle and a transponder circuit in several other vehicles which are friendly but could be mistaken for the enemy. In operation, the interrogator circuit transmits a time shifted code which is very difficult for an actual enemy to detect and/or jam, and which causes the transponder circuits to send a response from only a selected one of the other friendly vehicles that is being examined by the attack vehicle as a target.

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Salt Lake City, UT, United States of America

Richard J Saggio