Re: Spectrum Frequency Axis display issue in R1732 - with low sample rate

Ian DXer

On Sun, Mar 15, 2020 at 12:40 PM, prog wrote:
One of the reasons the IF plugin now displays the relative distance to the VFO and not the absolute frequency is exactly this problem.
Thanks for the prompt reply & info. Yes I'd been finding the IF plugin a more useful reference during the calibration procedure.

For the benefit of others when using the Airspy HF+ DP & preforming a frequency calibration from a cold start I found I needed to give the
HF+ DP a good 2 hours warm up from an ambient air temperature of around 22-23C. The frequency drift down from 258MHz was about 6Hz before stabilizing.
Interestingly whenever I switch off SDR# & exit SDR# & start it up again immediately, there's a typical 3Hz drift down over a 3-5minute period before settling on the correctly calibrated frequency display. 

Another observation when performing a frequency calibration with SDR# is that I only get a movement of carrier frequency on display every 3-4 ppb change in the CLK (PPB) figure.
I'm guessing that's also as per design & probably really pushing beyond design capabilities of hardware/software trying to improve.

>PS: I see your unit is well calibrated!
Seams to be or should be with the effort I've put in @ least at that frequency.
That said there is a 2Hz difference between what SDR# says compared to SDR Console, can always easily compensate for that with Simon's easy 'software' calibration tool in SDR Console.
Not sure however why my Airspy seams to still be on the higher end of 0.7Hz to 1.8Hz above local remote Kiwi SDR(GPS) units for Aussie x-band stations. 
I use the carrier offsets for keeping a tab(eye/ear) on Aussie xbanders for WRTH updates/editing.
I'll be comparing frequency accuracy on other frequencies later as I'm noting some variations & not sure why yet.



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