I do have a Rubidium 10mhz source that I feed into my flex. I think that the PT160 approach is a good approach. I could use one of these units and zero beat to the incoming signal. I presume that I will have to correct DDS error in the PTS160 as well. I should be able to look at the zero beat on my scope.
Will the audio chain in the Flex software pass thru low enough frequency to get a zero beat? Thank's for the info on the Paranormal Challenge. (I am able to move chess pieces around on a chess board by merely lookin at them, will that qualify?) George K2CM (Yes, FMT sickness has taken hold here) ________________________________________ From: [email protected] [[email protected]] on behalf of Alfred Green [[email protected]] Sent: Saturday, May 21, 2011 3:05 PM To: [email protected] Subject: Re: [FlexEdge] Frequency Measurement and the Flex (once again) On 5/21/2011 11:37 AM, AA8K73 GMail wrote: > > > As your FMT sickness progresses, you will be concerned about the > accuracy of the 10 MHz reference that you feed into the Flex. At this > time I am satisfied with a Trimble Thunderbolt GPSDO. > There are also some good Rubidium sources available cheaply. At least 1e-9 accuracy without tweaking. There are GPS-disciplined Rubidium oscillators around, probably the best you can do at the ham level without having access to a Caesium source. The Thunderbolt is very good, however. > > You will also discover that as you tune PowerSDR, the frequency may be > slightly off the Hertz shown, due to DDS rounding. Yes, but the DDS algorithm is known (with SR off), so for a given PSDR indicated frequency in Hz, it is possible to back-calculate what the true frequency is. I seem to remember someone (Brian?) doing measurements on this, and it is completely repeatable. I don't recall the calculation, but it is available. > > I want to experiment with a marker signal that I can derive from my > GPSDO, although I try to do the FMT with just the transceiver and the > GSPDO. > > You can pickup a PTS160 synthesizer pretty cheaply, and that will give you markers to 0.1Hz when locked to a good reference (standard option). For finer spacing, use a simple divide by 10 and get markers up to 16MHz at 10mHz accuracy. I've got all the gear to do it; I really must participate in a FMT at some point. I have however used similar techniques to measure the frequency of a 1296 beacon to a few tens of milliHerz. GL & 73, Alf NU8I Scottsdale AZ DM43an 160m > 24Gigs _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software. _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software.
