Re: [IRCA] New Grayland SDR WAV Files

[Guy Atkins <dx@xxxxxxxxxxxxx>]

Hi Chuck,

Sorry for the delay in getting back to you.

You've hit the nail on your head in your RSPduo assessment!
Performance-wise I find it's NOT in the ballpark of the "upper tier" of
consumer SDRs. The promised Holy Grail feature of software phasing remains
for developers to decide if the market is large enough to warrant their
efforts to add coherent tuners for phasing.

An SDRplay representative recently said it's not close on their radar, and
that's why they've decided to make the API open source. Hopefully someone
will pick up the ball and run with it, and deliver on what would be a
killer feature--if it works well!

Last week I made a day trip to Ocean City State Park, specifically to
compare SDR models on weak daytime signals. Ocean City, WA is well away
from strong RF, as is Grayland. Below is a summary I shared with some
others:

*I went to Ocean City State Park for a few hours, specifically to test the
RSPduo, FDM-S2, and HF+ receivers on weak daytime medium wave signals. The
antenna used was the Wellbrook ALA1530LN Pro, and all radios were operated
with SDR-Console V3 fed from a single 4-way antenna splitter. All coax from
the splitter to receivers was identical lengths of the same type of cable.
This way the only variables were the SDRs themselves...all modes,
bandwidths, etc. were the same.*

*My key takeaways, specifically related to MW weak signal performance:*


*The FDM-S2 gives excellent reception, that in my past experience equals or
out-performs a Perseus SDR *except* in strong signal areas (Perseus has
more built-in band pass filters to help protect the front end). Some others
have noticed the S2's "edge" over Perseus at times, too. *

*AirSpy HF+: I knew these are over achieving SDRs for the price, but
Friday's careful comparisons proved their outstanding performance! My HF+
receivers always equalled the FDM-S2. That's really saying something! NO
attenuator or gain adjustments on the HF+ are needed; it handles large
signals extremely well. If you dive far enough into settings you  *can*
make adjustments but it's not needed.*


*The RSPduo trails the pack significantly, with generally noisy reception
and "fiddly", complicated to adjust gain/attenuation settings for best
reception. I think the radio is great for the hobbyist with interests on
different bands, but except for the potential of eventual phased (coherent)
tuners in future versions of the software, there are better choices for the
MW DXer. That said, the RSPduo is the best performing SDRplay product yet.
Caveat: I may not have adjusted gain settings optimally on the RSPduo
before recording with it at Ocean City. However, at Grayland with this
radio and a 160 ft. DKAZ antenna I did little adjustment and found that I
was hearing the same DX the other fellas were hauling in. The radio didn't
seem noisy in that situation, either. My gut feeling though is that the
RSPduo is not a top tier SDR like the others. It's very good for the price
(plus the two tuners inside) but not up to the DX ability of the Elad or
AirSpy.*

*(Interestingly, with ALL FOUR receivers recording WAVs, the total CPU
usage was just 6.7% and the GPU usage (nVidia CUDA graphics card) was 75%.
Wow, 6.7% CPU with all radios recording full-bore?! I'm very pleased with
the horsepower of this "new" Dell workstation laptop.*

So Chuck, I've taken a lot more words to summarize what you stated so well.
The RSPduo is not a top contender but worth considering if a DXer wants to
cover a lot of other bands too.

73, Guy



On Sat, Sep 1, 2018 at 6:41 PM, Chuck Hutton <charlesh3@xxxxxxx> wrote:

> Guy:
>
>
> I'd be curious about your overall impression of the RSP Duo.
>
>
> I also own one andf came to the conclusion it can't match the HF+ or
> Perseus.  I consider its main value to be the promised (bit not yet
> delivered) support for phasing / nulling.
>
>
> Chuck
>
>
>
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