Assuming you're in the channel islands, you should be able to pick up BBC radio 4 long wave on 198kHz, if your SDR can handle frequencies that low. It's referenced to a rubidium standard and checked by NPL.
It can also be used to discipline a reference, or compared with some other local standard such as your frequency counter. http://www.qsl.net/pa2ohh/07freqstd.htm http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/time-and-frequency-bulletins-for-msf-droitwich-and-gps-off-air-signals On Mon, Apr 10, 2017 at 7:00 AM, Andre <[email protected]> wrote: > Hi all. > > I found something intriguing, on at least some SDRs the 28.8MHz crystal is > way off by about -2% > > Reset mine using Island FM to fine tune, a simple reverse biased blue LED > (6pF) to tweak the > > centre frequency a bit and now my 1990 vintage Black Star counter and SDR > agree correctly. > > > Actually found that blue LEDs make remarkably stable fixed capacitors, if > you reverse bias them with a > > moderate DC voltage a "useless" dim blue LED from a UPS makes a very good > wide range varicap diode. > > > Does anyone have an idea how to verify my calibration(s)? Unfortunately I > lack a Rb or Cs module > > but can (barely) get MSF here with a loop antena if it is far enough away > from lighting etc. > > Have a few random parts including some MK484 ICs so should be able to make > some sort of > > MSF bodge which will be stable long enough to calibrate the system. > > > It seems that Island FM actually calibrate against GPS so this should be > highly accurate. > > > -Andre > _______________________________________________ > 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.
