| 摘要 |
<p>The apparatus (10) for and method of generating a coherent signal whose amplitude, frequency and phase can be accurately controlled. A first and second signal from a signal source (16) are synthesized digitally in response to separate frequency and phase input data. The second synthesized signal is heterodyned with a coherent oscillator signal by a first mixer (38). This heterodyned signal, in turn, is heterodyned with the first synthesized signal by a second mixer (40) to produce a coherent signal generator output. The amplitude of the generator output signal may be varied in accordance with attenuation input data. A phase modulator (48) provides phase shift key modulation of the output signal in accordance with a phase control signal. In addition, a switch (42) gates the output of the final mixer (52) under control of a switch control circuit (44) which determines the pulse width and timing of the signal generator output.</p> |
