| 摘要 |
<p>Thus, a transceiver having a transmitter section and a receiver section is provided. The transmitter section includes a modulator to superimpose information, i.e., data, onto the amplitude of a suitable carrier signal, such as a microwave frequency carrier signal. The receiver section receives data carried by the carrier frequency signal and, in a heterodyning system, downconverts the received signal to a suitable intermediate frequency signal. The modulator and the downconverter are formed on a single semiconductor body, or chip of silicon. The receiver section is adapted to receive over a predetermined overall bandwidth signals having carrier frequencies within a plurality of frequency channels, each one of the channels having a predetermined channel bandwidth; and, a sampler for sampling such received signals at a sampling frequency less twice the predetermined overall bandwidth. The sampling frequency is selected to convert the carrier frequency of a signal within a selected one of the frequency channels to a frequency within a predetermined intermediate frequency and to convert the carrier frequencies of signals of the un-selected one of the frequency channels to frequencies other than the predetermined intermediate frequency. The downconverted signals are converted into corresponding digital signals. A demodulator includes a Hilbert-Transform-pair filter section. The receiver includes: a first automatic gain control circuit (AGC) and is responsive to an output of the digital signal processor, for adjusting the gain of the AGC circuit in accordance with the output of the digital signal processor; and, a second AGC circuit fed by the digital signals and the output of the digital signal processor, for adjusting the gain of the magnitude of the digital signals in accordance with the output of the digital signal processor.</p> |
