Abstract: In one aspect, a reference transmit signal is distributed to each of one or more transmit antennas, and delayed by multiple different times before transmission from the transmit antennas. The reference transmit signal (or a delayed version of the reference signal) is also used at each of the receive antennas to determine propagation (time of flight) times reflecting from bodies from each of the transmit antennas to the receive antenna. In another aspect, locations of multiple objects are determined by iteratively (a) determining a location of a body based on determined propagation times between multiple transmitter-receiver pairs, and (b) having determined a location, effectively removing the effect of reflections from that location from the remaining signals.

Abstract: A method for monitoring periodic motions of one or more subjects uses signal reflections from the subjects. The method includes emitting a transmitted signal from a transmitting antenna and receiving a received signal at one or more receiving antennas. The received signal includes a combination of a number of reflections of the transmitted signal, at least some of which are associated with the subjects. The received signal, including the reflections, is processed to determine an estimate of a fundamental frequency of the periodic motions.

Abstract: An offset estimator (e.g., a time delay, a spatial image offset, etc.) makes use of a transform approach (e.g., using Fast Fourier Transforms). The sparse nature of a cross-correlation is exploited by limiting the computation required in either or both of the forward and inverse transforms. For example, only a subset of the transform values (e.g., a regular subsampling of the values) is used. In some examples, an inverse transform yields a time aliased version of the cross-correlation. Further processing then identifies the most likely offset of the original signals by considering offsets that are consistent with the aliased output.

Abstract: In one aspect, a method for mitigating an effect of an interfering radio signal at a multiple antenna receiver includes forming an estimate of a relationship of the interfering signal among signals received from the multiple antennas. In general, the interfering signal does not share the same communication technology as a desired signal. The signals received from the multiple antennas filtered and combined according to the estimate of the relationship of the interfering channels to reduce an effect of the interfering signal. Desired data present in the desired signal represented in the filtered and combined signals is decoded and the estimate of the relationship of the interfering signals is updated according to the decoding of the desired signal.

Abstract: An offset estimator (e.g., a time delay, a spatial image offset, etc.) makes use of a transform approach (e.g., using Fast Fourier Transforms). The sparse nature of a cross-correlation is exploited by limiting the computation required in either or both of the forward and inverse transforms. For example, only a subset of the transform values (e.g., a regular subsampling of the values) is used. In some examples, an inverse transform yields a time aliased version of the cross-correlation. Further processing then identifies the most likely offset of the original signals by considering offsets that are consistent with the aliased output.

Abstract: In one aspect, a method for mitigating an effect of an interfering radio signal at a multiple antenna receiver includes forming an estimate of a relationship of the interfering signal among signals received from the multiple antennas. In general, the interfering signal does not share the same communication technology as a desired signal. The signals received from the multiple antennas filtered and combined according to the estimate of the relationship of the interfering channels to reduce an effect of the interfering signal. Desired data present in the desired signal represented in the filtered and combined signals is decoded and the estimate of the relationship of the interfering signals is updated according to the decoding of the desired signal.