Pulse or digital communications – Transmitters
Patent
1998-11-25
1999-11-02
Tse, Young T.
Pulse or digital communications
Transmitters
375308, 332103, 708313, H04L 2720
Patent
active
059784202
ABSTRACT:
In accordance with the present invention an interpolation technique is used to convert a low rate digital signal to a high rate signal and to shift the carrier to a desired frequency. This is accomplished, by first positioning the information signal, e.g., the digital waveform to be modulated on a carrier at a relatively low rate using a digital mixer operating at a fraction of the ultimate digital to analog conversion frequency. The relatively low rate signal generated by the mixing operation is then converted to a high rate signal by one or more interpolator stages. An adjustable passband filter circuit is included in each interpolation stage. One feature of the present invention is directed to a control circuit which is response to an H bit frequency control word representing a desired output carrier frequency. The control circuit generates individual filter control signals for each adjustable filter circuit from the single H bit frequency control word. An oscillator control circuit which is responsive to a portion of the H bit frequency control word is also described.
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Koslov Joshua L.
Lane Frank A.
Scarpa Carl G.
Hitachi America Ltd.
Michaelson Peter L.
Straub Michael P.
Tse Young T.
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