| 摘要 |
2102914 9221195 PCTABS00017 A dual-mode transmitter having an antenna (109), a mode controller (103), a source encoder, a tunable-frequency synthesizer (105), a chip-code generator (107), a spread-spectrum modulator (111), a narrowband modulator (113), a power amplifier (115), and an adjustable bandpass filter (117). Also provided is a dual-mode receiver having a mode controller (103), a tunable-frequency synthesizer (105), a chip-code generator (107), an antenna (109), an adjustable bandpass filter (117), a preamplifier (205), a frequency converter (209), an IF amplifier (211), a spread-spectrum despreader (215), a spread-spectrum demodulator (217), a narrowband modulator (213), and a source decoder. For the transmitter and receiver, the mode controller (103) selects receiving a narrowband modulation or a spread-spectrum modulation. The tunable-frequency synthesizer (105) generates a local oscillator signal for the receiver, and a carrier signal for the transmitter. The chip-code generator (107) generates a chip code signal for both the transmitter and the receiver. With a narrowband modulation setting of the mode controller (103), the transmitter and receiver have the adjustable bandpass filters (117) adjusted to a narrowband width for telephone communications. With a spread-spectrum setting of the mode controller, the adjustable bandpass filters (117) and the system are adjusted to transmit and receive a wide bandwidth for passing the spread-spectrum signal.
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