| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an RF modem which has frequency agility, is simple to implement, and can be constructed at low cost and small size. <P>SOLUTION: A bidirectional direct sequence spread spectrum half-duplex RF modem for transmitting and receiving analog and digital pulse modulation incorporates a SAW based correlator for performing the spreading and de-spreading functions in the transmitter and receiver. A programmable frequency synthesizer provides the frequency source for various signals in the modem including a local oscillator (LO), IF interrogating pulse and clock signals. An upconverter/downconverter provides frequency translation to a desired frequency band. Pulse gating and interrogating pulse shaping reduce the spectral side bands of a transmitted spread pulse. The RF modem operates as an analog or digital pulse transmitter and receiver and is applicable in data communication systems such as OOK, PWM and PPM. <P>COPYRIGHT: (C)2013,JPO&INPIT |
