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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 ?

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

Posted: 21 Feb 2018 16:25
by Tim Bucknall
If its great for SATCOM 243 - 260mhz I may be tempted.
But If this is a dongle type install ..I ain't got da skills innit

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

Posted: 21 Feb 2018 19:30
by satnipper
Plug it into USB socket Job done.

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

Posted: 21 Feb 2018 19:33
by Tim Bucknall
thats more like it, i don't have to install zdig or whatever it was called like with the dongles?

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

Posted: 21 Feb 2018 20:48
by satnipper
Zadig. No.

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

Posted: 21 Feb 2018 22:02
by Patrick73
Plug and play ! Once it's out of the box, you can use it 2 minutes later.

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

Posted: 24 Feb 2018 14:48
by Tim Bucknall
thanks Stuart & Patrick,
600khz is not bad I'm currently using ELAD in dual vfo mode which gives 384khz recording which is surprisingly useful when you only have a few clear channels at the bottom of the band, i centre it on 87.7 and record meteor pings all day

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

Posted: 07 Mar 2018 14:51
by Tim Bucknall
heres Bjarne's review https://app.box.com/s/d2dni57dzrsxgs38gxbbfz9gm26brqpk

he details a mod to increase medium wave sensitivity but says unless you like in a quiet location its prob not worth doing

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

Posted: 08 Mar 2018 12:41
by Tim Bucknall
OK a specific question, with the supplied software can fm b/w be infinitely varied?
30khz would be nice for satcom
i know it seems wierd to buy an sdr for just part of the mil air band but all the ones offering the full band at this price are flawed in some way.
anyway it sound like it will hear more on fm than my elad
and it would be nice to have access to lower oirt on a sdr

ps: apparently its 660khz IQ, don't knock those extra 60k, thats 2 more oirt channels! :D

looks like the weather will keep me stuck inside and bored crazy for at least another 2 weeks so i've bought airspy + and will prob get that data 808 portable