Happy days are here again - LimeSDR lives in HF!

@martywittrock @LY2SS

As I posted in the other thread, it works fine for me using 10 MHz sample rate and 100 MHz (!!!) bandwidth setting.

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Alex,

Yeah - I saw that and actually remember (now) that I had to set my Bandwidth to 100 MHz (and now I see it’s only 60 MHz) to make the lower end frequencies work. I had a notion that GQRX was okay and it was something related…

73 de Marty, KN0CK

@LY2SS,

While you’re setting up your other machine, please check out this thread and the messages below it:

It’s likely that you have to set your Bandwidth in GQRX to 60 MHz to have the lower end frequencies to show up - it’s a bug in the SoapySDR code, not GQRX. But it’s good that you’re setting up SDRConsole on your Win7 machine to balance between the two applications with your LimeSDR.

Let me know if you need anything else on this -

73 de Marty, KN0CK

As I have learned since, it is not necessarily a bug. We may improve it later, though.

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@Bernard,

Okay - I have a picture for you taken at 10:49 PM local time in Atkins, Iowa of the 50 kHz to 500 kHz bandwidth. There are actually several stations that come in and out with propagation, but there are some stations that have intelligibility to them - - here is that picture of the band at this time:

…and a short time later, it even got better (at 10:56 PM):

With a better VLF antenna, you could probably hear more stations than I can - And this is on LimeSDR V1.4 hardware on the modified RX1_W Port.

Please let me know if you need anything else, Bernard,

73 de Marty, KN0CK

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Thank you Marty, for having realized your two screen pages focusing on the lower part of the LimeSDR.
It’s very nice to know that the LimeSDR works relatively well towards 100 KHz and see below.
As you pointed out your antenna is not optimized for this Frequency range.

In Europe we have from 153 KHz to 279 KHz, nearly 30 Broadcast transmitters with power ranging from 10 KW to 2000 KW and mostly 500 KW

I would like to thank again sdr_research, who first tracked, the anomaly on the 100 kHz RX input, by this famous inductor not justified for the reception of low frequencies.
I wish that Myriad RF have gratitude for the service rendered to the community, to offer to our friend DO of Vietnam, sdr research, his expenses of Customs.

When do you think Andrew?

Thank you again, Marty, for taking the time to share this important information.
On receipt of my LimeSDR, when they want to release it and if it wants to work well, I will send you pages of screen of this famous range of frequencies
Very good continuation in your tests.
Thank you again and see you soon, I hope.
Best regards
Bernard MALET

Dear Andrews,
Still the same question:
When are you “Myriad RF” taking a frank decision HF to solve and finally deliver?
Andrews have you read my request for my friend Do, sdr_research?
Final question in the information to Marty :: Happy days are here again - LimeSDR lives in HF!
Good courage, Andrews
Best regards
Bernard

I have question : If I remove the coil by myself , how is warranty if LimeSDR fails ?
Today I receive my LimeSDR , just some test but I think you only remove one coil from LNA L , other input you keep intact in the case you want to using it for > 700MHz . I see the sensitive of LimeSDR at frequency below 150MHz as not sensitive as other SDR .

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Thanks for posting those spectra, @martywittrock! I would like to request a favor sometime. Could you feed the antenna output into one of your upconverters and then into the LimeSDR. The upconverted signals at 120 MHz (or whatever the upconverter LO is) should be in a more favorable range for the LimeSDR. I believe you will see a much different spectrum appearance. For example, the posted spectra show almost nothing between 300 and 400 KHz. This area is where the airport non-directional beacons (NDB’s) should be seen. Last night I checked that range with my Elad FDM-S2 and saw a “forest” of signals there. The VLF range is full of noise sources that create broad peaks and valleys in the noise floor (refer to the spectrum posted by @Bernard for a good example). I believe what you are seeing is a fairly deaf receiver in that range but with some images superimposed (I don’t think it’s just the antenna). I’ve been hoping someone would run an upconverter experiment on one of the low bands to see if the SNR improvement is significant or not. My LimeSDR is on-hold at CS until I decide how to proceed. Thanks for all your efforts to demonstrate the LimeSDR capabilities!

73’s
Chuck Conner

I have not kept up with navaids but I thought NDBs were phasing out. Is the plan behind schedule? Or is phase out moving faster in some places compared to others?

I did this back in May using my v1.2 board and here are some screenshots in case you are interested :relaxed:

  • Location: Denmark
  • Antenna: HyGain DX-88 vertical
  • Converter: Spyverter, 120 MHz LO, powered through USB

Thanks @csete, I had forgotten about those!

I’m still hoping to see a comparison of external upconversion versus internal upconversion in the lowest range specified for the LimeSDR (100 KHz to at least 500 KHz). I would expect the external upconversion to be much better. It would be interesting to know at what frequency the internal upconversion equals the external one (SNR-wise).

Chuck,

I don’t think I have posted these screenshot before, but I may be remembering wrong. My LimeSDR is quite deaf on LW and MW with the simple modif I made but I do not have a proper antenna for these bands. So, lets hope somebody else can make that comparison.

Chuck,

The screenshots I did for @Bernard last night were performed on a Hustler 6BTV that I knew would not be ideal in the VLF range - - there’s just not enough antenna there below 80m, let alone 160m. Certainly, adding the upconverter will match better to the range of the LimeSDR (that’s how I designed them - there’s a LPF and then a MAR 8+ 22dB preamp going into the 120 MHz upconversion) but I doubt that the severe mismatch of the antenna in the VLF range will be much better upconverted by 120MHz. I completely get why you want to see this - to see if there’s any further deficiency in the existing up-front matching network of the Lime with respect to a better receive sensitivity from 120 MHz and up. But again, I doubt you’ll see much from the VLF range because of my antenna not being perfect…It just wouldn’t be a fair comparison.

There are NDBs out there and if you look just above where I was tuned, there is the CW signal you can see in that range to the right of where I was tuned. We don’t have a lot of NDBs in the region (WLO in Waterloo is about it) and that’s likely the beacon you’ll see in the waterfall.

OK, I understand Marty. I think I was mostly wanting to confirm how bad the low end of the range was with the LimeSDR alone (no upconverter). My card is being held by Crowd Supply while I make a decision whether to cancel the order or not. I originally ordered it because I was interested in using the two receivers for phasing experiments. I’m not a ham so the transmitter aspects were of no concern to me. Knowing that the LimeSDR is going to require upconverters in order to perform decently at the low end is probably a deal-breaker for me. I’m going to keep monitoring the threads for the next week and then make the decision. Thanks again for your efforts!

Chuck

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Marty, you are the man.
I just modified mine a couple of minutes ago, no soldering iron needed. Just used a straight dental tool and an magnifying glass and with nearly no effort at all it popped right off.
And as you say, it lives!

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Todd,

Thanks for the kind words…It is amazing what the Lime will do once you lift the component that makes it work just as well at a MUCH higher frequency. After many months of running it in HF without the mod, with the mod it performs as well as some of the best SDRs out there. I’m not kidding, I really can’t tell the difference between my Flex5000A and the Lime in terms of receive - they are equally good, if not better on the Lime side.

Have fun with it and stay tuned for the HF transmit next…

73 de Marty, KN0CK

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Thx Marty,

I’d like to do a comparison to the my Atlas based HPSDR but my old laptop can only gin up 10MHz before it runs out of compute power.
My understanding was to set it to 65MHz centered on the main oscillator and use the lower half of the bandwidth for HF, did I get that right?

Todd,

For GQRX in either Windows or Linux that would be correct. For SDR Console (and running Windows) there’s no need to perform that step.

73 de Marty, KN0CK

Sweet, thx for the pointer. I’ll get that one going and see how it picks up compared.

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