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For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 22 Feb 2017 15:40
by Patrick73

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 22 Feb 2017 18:20
by pe1etr
The final bandwidth of 600 kHz might be a problem for many FMDXers, especially as the alternatives have several MHz bandwidth.

Peter Blackpool UK

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 22 Feb 2017 19:00
by Patrick73
This is indeed a downside ... But I rarely use more than 1.5 MHz BW.
Regarding this new SDR, I don't understand if the maximum BW is 600 kHz in any case, or if it's the final bandwidth after decimation ...

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 22 Feb 2017 19:28
by pe1etr
Patrick73 wrote:
22 Feb 2017 19:00
This is indeed a downside ... But I rarely use more than 1.5 MHz BW.
Regarding this new SDR, I don't understand if the maximum BW is 600 kHz in any case, or if it's the final bandwidth after decimation ...
Yes, the 600 kHz is after decimation. There doesn't seem to be an option to use the HF+ with less decimation or no decimation, like there is for Airspy.

Peter

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 02 Dec 2017 13:28
by Tim Bucknall
No driver required? Heard that one before :D

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 02 Dec 2017 14:48
by satnipper
No drivers required for the Funcube dongle. No reason to doubt what they say.

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 03 Dec 2017 00:04
by daveB
It is a trade off between ADC resolution and bandwidth. SDRPlay RSP1A now offers 14-bits resolution at sample rates of 6 MHz and below - which I guess would give an effective bandwidth of 5 MHz. In theory that should give an extra 12 dB dynamic range compared to the 12 bits of the Airspy/Airspy Mini/SDRPlay RSP1/RSP2.

The only SDR that offers 16 bit ADC with a wide (6MHz) bandwidth that I can see at a reasonable price is the Elad at around £500. The Airspy HF is going to be around £200 after you've paid VAT on it.

I find the SDRPlay and Airpsy Mini more than acceptable with 12 bit ADC for my location but they can be overloaded if you take the gain a bit high.

So your choices are:

RTL dongle - 8 bit ADC - cheap! (VHF/UHF/SHF)
Airspy Mini (VHF/UHF/SHF) - 12 bit dongle - 6MHz sample rate - but you can push it to 10 MHz - £120
Airspy (VHF/UHF/SHF) - 12 bit - 10 MHz sample rate - £210
SDRPlay RSP1A (VLF-SHF) - 14 bit ADC 6 MHz sample rate or 12 bit ADC at 8 MHz sample rate £91 (SDRPlay)
Airspy HF (HF/VHF) - 16/18 bit ADC - 600 kHz bandwidth - £229 (Moonraker)
Elad FDM2 (HF/VHF)- 16 bit ADC - 6 MHz sample rate - £460

The RSP1A is tempting if only for it's much improved filtering and gain distribution despite the better dynamic range offered by the Airspy HF.

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 24 Dec 2017 16:20
by Jim (Bournemouth)
My Airspy HF+ arrived on Friday.

Time to experiment has been somewhat limited, but have had a bit of time today.

First impressions:

It is certainly more sensitive than the Elad S2 barefoot, and just a touch more sensitive than the S2 and the Fringe preamp I use with it - but without the overload. The Elad overloads slightly especially at the bottom end when I beam towards Rowridge - that is a bind during the Es season.
It is also just as sensitive as the Perseus FM+, but that overloads here with some very strong artifacts on some frequencies.

The Airspy HF+ has the sensitivity, only without a hint of overload anywhere on Band 2.

As we already know, the max bandwidth is a little over 600khz, small compared with up to 10mhz for other SDRs, but to get this kind of performance with several Mhz of bandwidth.. the cost would be prohibitive for now at least.

A valuable addition to the arsenal here.

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 24 Dec 2017 20:13
by zach_m
Here is video comparing Airspy HF+ vs SDRPlay RSP1A on band 2: https://www.youtube.com/watch?v=OHw5O1kRUAM

My Airspy is still on its the way via Registered Airmail.

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 26 Dec 2017 14:13
by Patrick73
Thanks for the input Jim. This HF+ sounds very promising (I also own an ELAD S2) :P
Mine is also on the way ...

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 05 Jan 2018 12:11
by zach_m
My AirspyHF+ arrived today. It's a quite heavy device! 188g weight! Surprisingly Itead stated $10 on the custom declaration, so no customs either VAT costs. All in all, I end up paying £165 for everything.

Re: For demanding FM DX'er ... (18 bits ADC SDR)

Posted: 11 Jan 2018 10:55
by Patrick73
Just received my HF+ too :-)
First test on the french paraglading beacons (143.9875 - 1W) to test sensitivity : the noise level reading is about -137dBm running the HF+ and -117dBm running the ELAD S2 (using the same coax of course).

Did you notice the same 20 dBm discrepancy ?