FW: RK05 question

Gooijen> Hmm. So in your mind experiment you keep the 12 sector Gooijen> pulses and the track pulse, and deliver the track pulse with Gooijen> 16 sector pulses to the hardware of the drive logic. Using Gooijen> the 12 sector pulses will probably produce a more stable 16 Gooijen> sector pulse signal as the PLL is kept in lock in shorter Gooijen> intervals. Gooijen> But what would the PLL circuit do when it gets 12 sector Gooijen> pulses (that is fine) *_and_* at some odd moment the extra Gooijen> track pulse ...? If the loop bandwidth is right, it will ignore the track pulse as noise. That assumes that the sector pulses are spaced equally everywhere including at the track start. Gooijen> I was thinking of *only* the track pulse and get the PLL Gooijen> locked on that pulse only, assuming that the stability of Gooijen> the PLL is sufficient for one revolution. From the N divider Gooijen> is would be easy to get the sector pulses. So, I cover all Gooijen> the sector slits on the hub of the disk. I was thinking that the "right" design would work with unmodified packs, by electronically ignoring the marks it doesn't need. Gooijen> But as you said (I did not know that part and did not check Gooijen> on an RK05 pack I have at home), the track pulse is not Gooijen> halfway two sectors. Some separate binary comparator could Gooijen> check the N divider outputs and then you simply set a binary Gooijen> number to the comparator when it should give the track Gooijen> pulse. The key question is what the positions of the slots are. If the sector slots are equally spaced, they can drive a sector pulse PLL (and the track pulse can simply be taken from the track slot). If there's a spacing irregularity at the track start, then you'd need to create a high frequency clock from the track pulse, and divide it down to produce the sector pulses at the right spacing. That wouldn't be too hard either; for example, if you create a clock at 360x the track pulse rate, you get 1 degree resolution on your synthesized sector pulses... paul