Digital data and analog radio frequency transmitter
First Claim
1. An RF transmitter for transmitting either analog voice or digital data comprising:
- multiplexing means for switching between an analog voice input and digital data inputs to provide a selected signal, numerical oscillator means connected to the output of the multiplexing means for converting the selected signal to a digitally modulated numeric frequency signal,D/A conversion means connected to the output of the numerical oscillator means for converting the digitally modulated numeric frequency signal to an analog signal,first upconversion means connected to the output of the D/A conversion means for upconverting the analog signal to a first higher frequency signal,variable RF source means for providing a selected accurate preset frequency signal within a range of frequencies,second upconversion means connected to the output of the variable RF source means for upconverting the preset frequency signal to a second higher frequency signal,mixing means connected to the output of both the first and second upconversion means to provide a modulated signal,clock means connected to the numerical oscillator means, the variable RF source means and the first and second upconversion means for providing synchronization for each said means.
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Abstract
A digital Non Return to Zero (NRZ) and Frequency Modulated (FM) radio transmitter intended but not unique to, for the transmission of Digital, Tone Only or Tone and Voice paging messages is described. This transmitter is built on the concept that the separate signals required are individually constructed, and then combined together into the actual RF output. This provides for optimized circuitry for each particular function for the highest performance. There is no reason for compromising the performance of a particular function, and the implementation of the modulation and synthesis with direct digital technology provides extremely linear and fast radio performance at no extra cost. Maintenance is also simplified since the individual blocks can be troubleshooted and repaired (or replaced) requiring a minimum of down time.
202 Citations
11 Claims
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1. An RF transmitter for transmitting either analog voice or digital data comprising:
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multiplexing means for switching between an analog voice input and digital data inputs to provide a selected signal, numerical oscillator means connected to the output of the multiplexing means for converting the selected signal to a digitally modulated numeric frequency signal, D/A conversion means connected to the output of the numerical oscillator means for converting the digitally modulated numeric frequency signal to an analog signal, first upconversion means connected to the output of the D/A conversion means for upconverting the analog signal to a first higher frequency signal, variable RF source means for providing a selected accurate preset frequency signal within a range of frequencies, second upconversion means connected to the output of the variable RF source means for upconverting the preset frequency signal to a second higher frequency signal, mixing means connected to the output of both the first and second upconversion means to provide a modulated signal, clock means connected to the numerical oscillator means, the variable RF source means and the first and second upconversion means for providing synchronization for each said means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification