Re: Feedback for version 0.9a here
Posted: Wed Jul 11, 2018 8:02 pm
Hi, sorry for slight delay in reply but work has got in the way a bit. With alpha software testing I deliberately set out to try and break it, doing things typical users might do or not do. I ask anyone who tests my alpha software to do the same as in my experience it's invariably early users who find things that I've overlooked and any failures they find can be very valuable. Therefore please don't take my results or comments as critical of your excellent software!
In this case I wanted to see what happened if the SAS system as a whole was used to try and obtain measurements but without any "proper" connections or setting up - just a pick up wire.
Neither the pickup wire nor the RSP and its USB connection were moved between tests. I keyed the TX and took a signal level reading off the screen using the cursor, with so far as I'm aware everything in the software at default. The big differences compared to your results, since you have confirmed you are using the calibration tables mentioned by SDRPlay Support, indicate something is probably awry in the measurement setup?
My PC and TX are strapped together to a common ground, but fairly close physically so it's conceivable there's unstable pickup going on with just a bit of wire, particularly at these low signal levels.
I'll re-run my tests using a different dummy load that has an attenuated tap-off and consequent direct cable connection to the RSP. Hopefully that will be better, but I'll have to check the tap output levels are suitable first as it's normally used with a 'scope. I'll also repeat the pickup wire tests using battery power on a laptop, so the RSP is entirely separated from the rig.
If this then shows marked improvement in variations then maybe some guidance on setting up to take measurements would seem to be useful?
I'm not prepared to name the other software and hardware I tested on a public forum, particularly given the wide variation between SDRUno and SAS that indicates something else is probably at play here.
Link to forum post re the calibrated analyser - viewtopic.php?f=12&t=3323#p10608 and then the blog referenced within, but my mistake in arithmetic - it's 10.7dB not 12dB difference, my apologies!
In this case I wanted to see what happened if the SAS system as a whole was used to try and obtain measurements but without any "proper" connections or setting up - just a pick up wire.
Neither the pickup wire nor the RSP and its USB connection were moved between tests. I keyed the TX and took a signal level reading off the screen using the cursor, with so far as I'm aware everything in the software at default. The big differences compared to your results, since you have confirmed you are using the calibration tables mentioned by SDRPlay Support, indicate something is probably awry in the measurement setup?
My PC and TX are strapped together to a common ground, but fairly close physically so it's conceivable there's unstable pickup going on with just a bit of wire, particularly at these low signal levels.
I'll re-run my tests using a different dummy load that has an attenuated tap-off and consequent direct cable connection to the RSP. Hopefully that will be better, but I'll have to check the tap output levels are suitable first as it's normally used with a 'scope. I'll also repeat the pickup wire tests using battery power on a laptop, so the RSP is entirely separated from the rig.
If this then shows marked improvement in variations then maybe some guidance on setting up to take measurements would seem to be useful?
I'm not prepared to name the other software and hardware I tested on a public forum, particularly given the wide variation between SDRUno and SAS that indicates something else is probably at play here.
Link to forum post re the calibrated analyser - viewtopic.php?f=12&t=3323#p10608 and then the blog referenced within, but my mistake in arithmetic - it's 10.7dB not 12dB difference, my apologies!