Absolutely, that's what the pictures I linked to earlier show, particularly the last one. It is sufficient to properly terminate one end to eliminate ringing, as long as you have no tees in line. There may be specific reasons why it is preferable to terminate one end rather than the other, like protecting the driver.
In any case, if the pulse is narrow, the risk of damage to the driver because of short to ground is also greatly reduced. In my experience, I prefer to terminate the end because it tends to reduce the noise sensitivity at the receiver (not just for timing, but for anything where noise is critical). If the amplitude is too great, I put a matched divider at the end. I always try to have as much signal amplitude on the cable as possible to improve the S/N ratio. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -----Original Message----- From: Hal Murray <[email protected]> Sender: [email protected] Date: Tue, 15 May 2012 15:02:36 To: Discussion of precise time and frequency measurement<[email protected]> Reply-To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] Why are 1PPS signals so skinny? [email protected] said: > Also, the Thunderbolt has less than 5 Ohms output impedance, so you get a > reflection going back from the 50 Ohms end-termination anyway because the > impedance is mismatched! I think that's a different problem. If the far end termination matches the cable there won't be any reflection. If the far end isn't terminated correctly, there will be reflections from the far end. There may also be reflections from joints in cables or a Tee and input load if you are daisy chaining multiple instruments. When those reflections get back to the typical low impedance driver, they will get reflected back again. It's not uncommon to use both source/series and end/parallel terminations. The series terminator drops the signal level by 2 but minimizes reflections if you are working in a less than ideal setup. It also provides a current limit on the driver in case something gets shorted. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
