초록 ▼

A digital compensation filtering technique is provided that enables indirect phase locked loop modulation with a digital modulation data stream having a bandwidth that exceeds, perhaps by an order of magnitude, the bandwidth characteristic of the phase locked loop. A modulation data receiver is prov

A digital compensation filtering technique is provided that enables indirect phase locked loop modulation with a digital modulation data stream having a bandwidth that exceeds, perhaps by an order of magnitude, the bandwidth characteristic of the phase locked loop. A modulation data receiver is provided for receiving from a modulation source digital input modulation data having a bandwidth that exceeds the cutoff frequency characteristic of the phase locked loop frequency response. A digital processor is coupled to the modulation data receiver for digitally processing the input modulation data to amplify modulation data at frequencies higher than the phase locked loop cutoff frequency. This digital processor is connected to the phase locked loop frequency divider to modulate the divider based on the digitally-processed input modulation data, whereby a voltage controlled oscillator of the phase locked loop is controlled to produce a modulated output carrier signal having a modulation bandwidth that exceeds the phase locked loop cutoff frequency. The digital processing of the modulation data can be implemented by adapting a digital FIR Gaussian transmit filter such that its filter characteristic reflects the intended modulation data amplification as well as enables Gaussian Frequency Shift Keyed modulation. With this implementation, no additional componentry beyond the PLL system is needed to implement the digital modulation data processing provided by the invention.

대표청구항 ▼

[ We claim:] [1.] Apparatus for modulating a phase locked loop, the phase locked loop comprising a voltage controlled oscillator responsive to a control signal for generating an output carrier signal that is modulated by input modulation data and that has a controlled frequency; a reference frequenc

[ We claim:] [1.] Apparatus for modulating a phase locked loop, the phase locked loop comprising a voltage controlled oscillator responsive to a control signal for generating an output carrier signal that is modulated by input modulation data and that has a controlled frequency; a reference frequency signal source; a phase comparator connected to receive a reference frequency signal and the modulated output carrier signal for generating a difference signal; a low pass loop filter connected to filter the difference signal for producing the voltage controlled oscillator control signal; and frequency divider means connected between the voltage controlled oscillator output and the phase comparator for dividing the output carrier signal frequency; the phase locked loop being characterized by a frequency response having a characteristic cutoff frequency; the apparatus comprising:means for receiving from a modulation source digital input modulation data having a bandwidth that exceeds the cutoff frequency of the phase locked loop frequency response; andmeans coupled to the modulation data receiving means for digitally processing the input modulation data to amplify modulation data at frequencies higher than the phase locked loop cutoff frequency, and connected to the phase locked loop frequency divider means to modulate the divider means based on the digitally-processed input modulation data, whereby the voltage controlled oscillator is controlled to produce a modulated output carrier signal having a modulation bandwidth that exceeds the phase locked loop cutoff frequency.