The present invention is a method and an apparatus to use carrierless
signals for energizing remote passive or active transponders (tags) and
for communication link between a reader and the transponders. The
reader's transceiver generates very short high power pulses to transmit
them to the transponder which receives and stores the pulse energy in an
energy store on the transponder. At the transponder the power pulse
signal is compressed by a matched filter and rectified. Information to be
transmitted from the reader to the transponder and from the transponder
to the reader can be added to the data pulses by means of pulse position
modulation, bi-phase modulation or other well-known wide-band modulation
techniques. The communication is active as the transponder utilizes
stored power for transmission and reception of signals while the
transponder can be passive and is powered by the reader's signal energy.