I'll tell you guys - I've been following this link since it's inception and you REALLY have my curiosity piqued!! I've used TDRs quite a bit in a past life and I DEPENDED on the visual representation on the screen to interpret what is really on the line! I don't think I EVER had a clean line that didn't require some interpretation - was that hiccup a sharp bend? water in the line? an unauthorized tap? A long-forgotten splice? etc. How do you plan to accomplish this using a PIC or an oscillator circuit???? Or don't you? Just looking to determine overall length to the most significant reflection?? ----- Original Message ----- From: "michael brown" To: Sent: Thursday, February 20, 2003 10:33 AM Subject: Re: [PIC]: How would I build a reflectometer? > From: "Michael Rigby-Jones" > To: > Sent: Thursday, February 20, 2003 5:47 AM > Subject: Re: [PIC]: How would I build a reflectometer? > > > > > There might be some way the pulse transit time on the cable might be > made > > > into a sort of oscillator circuit. > > > > > That's basicaly what Wagner suggested a few posts back. I was > thinking you > > could perhaps do away with pulse reflections all together and just use > cable > > capacitance with some calibrations for cable type. It might be able > to be > > made accurate enough for some applications, but TDR is the way to go > for > > real accuracy. > > I was thinking about this approach. I've seen it referred to as a > "gimmick" capacitor. I didn't know how much effect the "real world" > might have on it though (fluorescent lights, noise, etc..). I will do > some experiments at various customer sites that are wired using the same > cable type. I already know the lengths there as well. > > michael > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu