An apparatus for preparing a RF radar transmit waveform and for decoding RF return waveforms comprising: a RF-lightwave encoder and a decoding preprocessor to phase-encode the RF radar transmit waveform and partially decode the return signal, the encoder including switched optical delay lines for producing desired RF phase shifts, and the decoding preprocessor including a tapped optical delay line and optical delay lines that counteract the delays imposed by the delay lines of the encoder, wherein the RF-lightwave encoder and the decoders allow shorter compressed pulses and larger pulse-compression ratios to be achieved than can be obtained using conventional electronic approaches. Wideband transmit waveforms can be generated due to the use of the switched optical delay lines and, unlike prior art approaches, is not restricted to single-frequency waveforms. The taps can be weighted to accomplish objectives such as reduction of side lobes in the compressed pulse.
In Bluethooth medium rate packets, the access code and the header are frequently modulated by Gausian Frequency Shift Keying, and the actual payload is phase-modulated by a differential Quadrature Phase Shift Keying or an 8-ary DQPSK scheme. Guard time and a synchronization sequence are placed between the header and the payload parts because of the need to change the modulation scheme and because of the ease in packet transfer. A sequence having a form of ABA is added to a Barker sequence having a form of BABBAAA for providing the synchronization sequence having the form of ABABABBAAA, where A and B are different states in a binary representation.
The present invention provides a radio signal radiation system that alleviates the necessity of a highly specified pass band reception filter and a high performance/reliability amplifier. The radio signal radiation system includes an optical modulator; a light source for inputting an optical carrier wave into the optical modulator; a power source for applying a modulating signal having a frequency Fm on the optical modulator to superimpose a sideband wave onto the carrier wave, the modulating signal having an amplitude of N-times the drive voltage of the optical modulator; a light receiver to receive and convert the outgoing light into an electrical signal; and a radiating means for radiating a radio signal based on the electrical signal, wherein the sideband wave is superimposed at a position shifted by n.times.fm.
