I did some further testing with a Kenwood LF-30A Lowpass Filter installed (to remove FM images) and used SAME SETTINGS again on the V1.2 and V1.4 hardware. Here are the results (and 20m is better in both cases):
I just see better activity on the V1.2 hardware than I do on the V1.4 hardware.
I do agree with N1JEZ’s assessment (and even saw this when HF wasn’t developed yet and all there was, was tuning above 30 MHz) that upconverted HF always looked better to the LimeSDR than native HF. Now I realize that some of that is based on the matching networks on the board for receive - they aren’t optimized. But the V1.4 boards were supposed to be better for the LNA-L Port, but I’ve seen confirmed reports from others that the LNA-H Port runs better (and this was even true on V1.2 hardware up to 8 months ago).
Not complaining - just want to know what’s going to be done to make this better for those who’ve bought boards - there is obviously a difference in the hardware and I’m not sure if it’s because of the matching networks or gain settings that haven’t been realized yet for the HF/SWL tuning range.
Quick and very non-professional tests here show the current firmware seems ~ 20dB deaf between 88 and 108MHz compared to the Airspy - same as you’re seeing on HF. I agree that LNA-H is better than LNA-L on FM Stereo, no idea why etc.
I have two PCs and run Airspy on one as my reference / FM Stereo / repeater receiver.
I guess it’s just firmware as turning up the gains too high results on an IQ stream value of 0.
Agree - I just wonder why the difference between the V1.2 and V1.4 hardware…That’s the part that’s confounding because even the V1.2 hardware was respectable with most of the bands. What we have now in V1.4 is not right - - and, like you, feel there’s gain settings that aren’t there yet, too.
In other news, your SDRConsole app is running great on either hardware for me using Zack’s DLL (I see from Paul that your DLL works, too). Nice job on the app, Simon…It’s a winner…!!
GQRX for Windows won’t receive anything with either hardware (V1.2 and V1.4) and the Linux version is completely broken - I completely uninstalled and reloaded all the LimeSuite and SoapySDR support for 16.10 (Yakkety-Yak) and while LimeSuite works like a charm, GQRX is reporting a serious crash (something about a segmentation error). So I’m doing all these comparisons with SDRConsole. Glad to see that you’re seeing this, too.
I now have the LimeSDR roughly as sensitive as the Airspy (user error here). What I don’t understand is the noise either side on this screenshot (below 90MHz and above 106MHz):
I have the Pothos build from a couple of weeks ago, but for some reason it cannot hear anything below 9 MHz and I see no signals from V1.2 or V1.4 hardware no matter what happens. It’s weird, because it does work fine above 9 MHz and I see not only FM, but my local weather station at 152.475 MHz is in great shape, too. The build for the Linux box is completely broken - I’m in contact with Alex about it.
Thanks for the info and sharing your pic of it working in Windows, Mike -
Just a quick update this morning that I reloaded my V1.4 hardware from LimeSuite this morning and then checked out the 20m band…It’s looking REAL GOOD on 20m, about the same on 40m, and pretty deaf on 75m (which was somewhat the case with the V1.2 HW, but at least I heard something - now, not so much). Looking better on 20m…here’s the screenshot:
I’ve had a break through on the LimeSDR sensitivity on 6M through 432.
The key is to turn down the internal Lime LNA and use an external LNA for the band you’re on. Also, pay no attention to the frequency markings on the antenna ports. Try all three and use the best.
I’ve been using a GVA-63 for testing as I had one here all made up for another project (5760 driver). Not a very good NF.
On 6M, I started out at -115 as the reference for MDS using the LNA_L port. I changed to the LNA_W port and went down to -123. I then inserted the GVA-63 which only has 7 dB gain and went to -128. This is with the internal Lime LNA set at -15. Any higher and it’s just noise. I bet a higher gain LNA will lower the MDS further.
I saw -128 to -141 on 2M. On 222, picked up 7 dB and on 432 10 dB. 222 and 432 weren’t too bad to start.
I plan to try some PGA-103’s which have a much better noise figure.
Simon, correct, HF is down, and no broadcast AM band, Medium Wave to the EU guys but performance in the real world not on a signal generator, but on antenna is dismal… At least 40db down on even the RTL with upconverter… And this is on real antennas. Not bits of wire, a 4el 6 band beam and a 1500ft loop…just for starters…
but performance in the real world not on a signal generator, but on antenna is dismal… At least 40db down on even the RTL with upconverter… And this is on real antennas. Not bits of wire, a 4el 6 band beam and a 1500ft loop…just for starters…