Re: [time-nuts] crystal (or MEMS) oscillators with low hysteresis
Hi I'm guessing that power is also an issue, so cheap OCXO's are out. If that's true, I believe you are already at the cheap vs good inflection point with the cell phone TCXO. At $2 they are pretty tough to beat. Just the fancy crystal in something better is going to give you a big boost in the price. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Friday, September 07, 2012 11:36 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] crystal (or MEMS) oscillators with low hysteresis Consulting the hive-mind here on the list.. If one were looking for small/cheap/mass produced oscillators which have decent phase noise.. what kind has the most repeatable frequency vs temperature curve. The usual 1ppm TCXO has about 0.1 ppm hysteresis, while other less stable oscillators may have bigger variation with temperature (1ppm/degree C isn't a problem) but be more repeatable (perhaps the kind that they use as a thermometer?) And, then, are those available in an inexpensive mass produced form (e.g. the precision quartz thermometer is NOT inexpensive or mass produced) Phase noise need (not a hard requirement) is not a big driver -45 @ 1 Hz -75 @ 10 Hz -105 @ 100 Hz -130 @ 1 kHz -145 floor out to 15 MHz The parts I use now are actually about 10 dB better than that (-58 at 1 Hz, -90 @ 10 Hz, -117 at 100 Hz, and floor of -153) Ideally, I'd like to find something that has zero hysteresis.. BUT, if there is an equation that can predict the hysteresis by knowing the temperature history, that would probably work (although that has a bunch of problems... what about temperature changes when power is off) This isn't a spec that typically shows up in the mass produced XO catalog: they focus more on bounding the frequency error over some range of environments .. good to within 50 ppm from 10-55 C or something like that. So I'm looking for practical experience. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] crystal (or MEMS) oscillators with low hysteresis
On 9/7/12 12:20 PM, Bob Camp wrote: Hi I'm guessing that power is also an issue, so cheap OCXO's are out. If that's true, I believe you are already at the cheap vs good inflection point with the cell phone TCXO. At $2 they are pretty tough to beat. Just the fancy crystal in something better is going to give you a big boost in the price. power and size.. Yes.. the cellphone tcxo is probably it.. but I was wondering if something else that's not TC might not have better hysteresis properties. Short of buying a batch and trying them... which I'll do, but before just randomly picking things out of the Digikey catalog, it's possible someone has more insight into the inner workings of cheap clock oscillators. For instance, they make inexpensive fairly high performance low power oscillators for COSPAS (emergency locator beacon) and wildlife tracker use. But you'd never know that they have the higher performance unless you asked. AT the high, expensive end, I've got all the data I need.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] crystal (or MEMS) oscillators with low hysteresis
Hi The crystals in the TCXO's are about as well mounted for hysteresis as you can practically do for the money. A typical clock oscillator guy does not worry much about that sort of mounting. Sorting is going to be a good idea. There are a number of things you likely will want to weed out. I'd plan on looking at a couple of different frequencies as well as vendors. Some quality time with a slow ramp / high data rate test setup should tell you a lot. 100 readings a degree and sub 1 degree per minute is the typical way to do it. Getting your temperature probe so it doesn't lag can be a hassle even at 1C/ minute Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Friday, September 07, 2012 4:10 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] crystal (or MEMS) oscillators with low hysteresis On 9/7/12 12:20 PM, Bob Camp wrote: Hi I'm guessing that power is also an issue, so cheap OCXO's are out. If that's true, I believe you are already at the cheap vs good inflection point with the cell phone TCXO. At $2 they are pretty tough to beat. Just the fancy crystal in something better is going to give you a big boost in the price. power and size.. Yes.. the cellphone tcxo is probably it.. but I was wondering if something else that's not TC might not have better hysteresis properties. Short of buying a batch and trying them... which I'll do, but before just randomly picking things out of the Digikey catalog, it's possible someone has more insight into the inner workings of cheap clock oscillators. For instance, they make inexpensive fairly high performance low power oscillators for COSPAS (emergency locator beacon) and wildlife tracker use. But you'd never know that they have the higher performance unless you asked. AT the high, expensive end, I've got all the data I need.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
