The pulse train output from the delay generator goes to the pulse selector, which serves to reduce the repetition rate of the pulse train by periodically blocking pulses.
where [[phi].sub.src,i] is the phase of the source output signal; [[theta].sub.src,ref] is the phase delay between the reference output from the source and the reference input of the delay generator, which is constant; [[theta].sub.dg] is the phase delay between the pulse output of the delay generator and the pulse selector (its purpose is described in more detail in Sec.
Understanding the purpose of the pulse selector is critical.
* The pulse selector must not allow more than one sampling pulse to transmit for each period of the sine wave (except, perhaps, for the case of low-frequency signals, as previously discussed).
The criterion for the pulse selector is that it allows only one [[phi].sub.calc,i] to be measured per period of a given sine wave and for a given delay, j.