| 摘要 |
A device for transforming N-Frequency Division Multiplexed (FDM) channels (21) of modulated signals into individually accessible streams (46) of demodulated data employs a Fourier transform processor (10) to transform the N-FDM channels into a single, TDM (Time Division Multiplex) channel of data, a single demodulator (12) for demodulating the single TDM channel and a demultiplexer (14) for demultiplexing the single channel of TDM data. The symbol segments of the N-FDM channels are synchronized with each other using an error signal generator (78) and a dither technique in which a symbol window is shifted back and forth to determine whether the symbol segments are early, on time or late. In a preferred form, the demodulator and error signal generator are implemented using digital techniques. The Fourier transform processor (10) includes a pair of analog dispersion sections (26, 42) for introducing delays in the FDM signals as nominal monotonic delay functions of frequency, a frequency sweep section (35) and a calibration section (45) for compensating for deviations in the differential delay for functions such that the output of the second analog dispersion section is substantially that calculated for an ideal system.
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