<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Following up on the Denon use of Quad and how I ran across that: Googling for information on Pulse <i>Interval</i> Modulation (PIM) and International Video Corp.'s use of the technique for recording video on its successful 1" helical recorders.</div><div><br></div><div>The technology is described in IVC 800 series manuals as : </div><div><div><br></div><div>"...wherein the interval of the wave generated by an oscillator is inversely porportional to the amplitude of the modulating waveform. Advantages of this method of modulation are improved signal-to-noise ratio, greater bandwidth and improved linearity."</div><div><br></div><div>And perhaps no patent licensing?</div><div><br></div></div><div>The demodulation process produces "a series of spikes at twice the frequency of the modulated signal. These spikes are used by demodulator Q11 to generate a sawtooth waveform whose average area is a linear function of the modulated wave."</div><div><br></div><div>"After passing through emitter follower Q12, the signal is passed to the averaging filter (L3, L4, L5 and associated capacitors) a low pass filter which removes all frequencies above approximately 5MHz."</div><div><br></div><div>"The resulting composite video signal is then equalized for optimum frequency response (C53 and R95) amplified by Q14, Q16 and Q 17 and passed to two emitter follower stages, one for black and white video output and the other to furnish the required drive to the color processor."</div><div><br></div><div>Did other video recorders use PIM to lay a signal onto tape?</div><div><br></div><div>Ted</div><div><br></div><br><div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Ted Langdell</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Secretary</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" color="#0018ea" style="font: normal normal normal 12px/normal Helvetica; color: rgb(0, 24, 234); "></font></div></div></div></span> </div><br></body></html>