Channelized multicarrier digitizer

摘要

A method is provided for individually processing multiple frequency bands in a composite RF signal is disclosed. The composite RF signal is separated into a plurality of gain controlled and bandlimited frequency bands. The gain controlled and bandlimited frequency bands are then recombined to produce a controlled composite RF signal, which is then digitized by undersampling with an ADC to produce a plurality of unambiguous frequency bands convolved around baseband. The sample frequency can be substantially less than the Nyquist Limit of twice the highest frequency present for digitization. Each baseband signal is monitored for amplitude spikes therein. In response to an amplitude spike, the appropriate frequency band is modified by a control signal to hold the ADC to within its dynamic range.

主权项

1. A circuit for individually processing multiple frequency bands in a composite RF signal, comprising:
an antenna for receiving the composite RF signal; a power splitter connected to the antenna operable to receive the composite RF signal, the power splitter having an input node and a plurality of output nodes and operable to split the composite RF signal into a plurality of composite RF signals of substantially equal power; a plurality of signal modifiers each having an input node, an output node, and a control node, the input node of the signal modifier connected to one of a corresponding output nodes of the power splitter, wherein the signal modifiers are each configured to isolate a frequency band of interest in the composite RF signal without mixing and without down converting the composite RF signal; a power combiner having a plurality of input nodes and an output node, each one of the input nodes of the power combiner connected to a corresponding output node of one of the signal modifiers to produce a controlled composite RF signal at the output of the power combiner; an analog to digital converter (“ADC”) connected to the power combiner and configured to convert the controlled composite RF signal into an output signal comprising a plurality of unambiguous individual base band signals by undersampling the controlled composite RF signal at a sampling frequency (“FS”) less than a Nyquist sampling rate for the composite RF signal; and a controller responsive to the ADC to compare an amplitude for each of the plurality of unambiguous individual base band signals with a predefined value in order to provide a control signal to the control node of the signal modifier corresponding to the frequency band of interest, which frequency band of interest corresponds to one of the unambiguous base band signals, to substantially maintain a power level for the frequency band of interest in the composite RF signal.