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Author Topic: Sherwood Engineering Receiver Test Data  (Read 2267 times)

W6RZ

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Re: Sherwood Engineering Receiver Test Data
« Reply #45 on: March 21, 2021, 12:05:50 AM »

The Hermes Lite 2 SDR runs its 1 Gb/s Ethernet stack on a state machine inside an FPGA, no CPU in the box.  Open source, so you can read the Verilog.  About twice the price of an SDRPlay, but you get a full duplex QRP transceiver in exchange.

Heh, I knew I should have said "or FPGA". However, given the crowd funded build model of the Hermes Lite 2, is it being sold at cost? If so, it's not a good price comparison to products trying to make a few shekels.
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N6YWU

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Re: Sherwood Engineering Receiver Test Data
« Reply #46 on: March 21, 2021, 09:16:28 AM »

"With an RTL-SDR, you can DSP process up to 2 MHz of bandwidth on a Raspberry Pi"

So, this would require a minimum of 4 MSPS of processong bandwidth (NOT I/O bandwidth), divided by the number of CPU cycles it takes to execute a single usable usable filter response, like a 16-64 pole FIR filter with DECENT dynamic range (at least 16 bits mantissa), or a somewhat shorter IIR filter (with ringing).

1.5 GHz/10 clock cycles per machine instruction cycle/~1000 arithmentic+move&store cycles per useful DSP filter function = about 150 Khz bandwidth.  Clever algorithm minimization could do better, perhaps - but you would still be very CPU constrained.

I could be clever, but for quick simple DSP experiments I prefer brute force.  A Raspberry Pi 4 (with its 4-wide SIMD FPU) can do over 10k complex float FFTs (length 4096) per second, which easily allows running 2000+ tap fast convolution FIR filters directly on a 2 Msample/s IQ stream without downsampling...

...using just one of the Pi's 4 CPU cores...

...on a $35 toy educational computer (a more expensive but equally portable iPhone 12 is on the order of a magnitude faster at simple DSP than a Pi 4).  The Pi 4 did need a heat sink.
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N2DTS

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Re: Sherwood Engineering Receiver Test Data
« Reply #47 on: March 24, 2021, 05:52:21 PM »

I bought an airspy discovery and have tested it out.
Maybe because its new, but I had a hard time getting it working.
sdr# did work after much head scratching and dll file fighting, along with sound card issues, program not responding and the program only opening in the file location, not on the desktop shortcut.
I also had to download a bunch of .NET. stuff.

The radio seemed to work very well once it started working.
I do NOT like sdr#. Its swl software, not ham software, no band buttons, no band stacking.

Audio and display are great.

I then downloaded HDSDR and fought the DLL fight again but it had the audio sound like frogs talking.

I have a problem using swl software for ham operation.
Some software does a good job, sdr console has/had band buttons, filter width buttons and other ham friendly controls on the screen.
Powersdr is my standard and KE9NS is king.

The hardware might be good, the software is lacking.

The radio itself is really small!


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N2DTS

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Re: Sherwood Engineering Receiver Test Data
« Reply #48 on: March 24, 2021, 07:22:14 PM »

Sdr console worked right off the bat, has the discovery listed in the latest version.
Works great, but the ham band buttons are gone, or at least I could not find them.
sdr# has no s meter?
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N6YWU

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Re: Sherwood Engineering Receiver Test Data
« Reply #49 on: March 25, 2021, 08:44:58 AM »

I have a problem using swl software for ham operation.

The HF+ is a receiver, not a ham transceiver.  Thus not limited to "bands".

The HF+ can also provide up to a 768 kHz wide spectrum. Thus you can see an entire HF band in the waterfall and pick any spot you want.  So why do you need old-fashioned band stacking buttons on your computer display (which has no physical buttons anyway)?  On my iPad or Mac, I just swipe to any spot in the band I want to see with my HF+, and zoom in.
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N2DTS

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Re: Sherwood Engineering Receiver Test Data
« Reply #50 on: March 25, 2021, 04:54:52 PM »

Because its a lot easier to use band stacking registers.
I want to look at 160 phone, click the button, its on the frequency I want.
Click the 160 button again to check out CW part of the band, then click 40 meters, its right at 7290 where I want to be, click it again and its on 7120, old novice CW section. It changes mode and filter settings per band and per stack.

I can not see any detail if I am looking at a MHz wide display on a screen, and its not so easy to jump from 1885, to 3885, to 3560, to 7290, to 14.300, to 50.4, then to 7060 changing mode every change.

Maybe you never had a good program, or a radio with band stacking, I am interested in the ham bands 99%, and this is a ham radio site.

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K6BRN

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Re: Sherwood Engineering Receiver Test Data
« Reply #51 on: March 25, 2021, 07:42:44 PM »

"You’d be better served to contact Rob to see if he’s interested in testing the AirSpy HF+. I’ve already offered him one and a couple from SDRPlay but he declined."

So...  I guess Rob Sherwood won't be reviewing the AirSpy after all, anytime soon, as an HF contest receiver.  (Sigh!)

Would've made a really great YouTube video.

Well - maybe someone here could create their OWN list with tested performance parameters - at least to compare the Airspy and RSP-1, RSP-2, etc.  THAT really WOULD be useful.  That person would have to have some technical chops, be comfortable in a lab, have access to and know how to use professional grade equipment and also understand how to collect, record and reduce the data.

It would take real work, need to yield real, repeatable and relevant results, and would probably be subject to some scrutiny, like Rob's list and his data.

Rob's list has pretty much tracked and sometimes even driven the evolution of amateur radio receivers (by making buyers more aware of key performance metrics) .  There is clearly a similar opportunity to pick up that ball and run with it in the case of  very low cost "digital" receivers.  Today, there is no such guide to even debate.  Opportunity knocks.  Loudly.

Any takers?

Brian - K6BRN
« Last Edit: March 25, 2021, 07:49:28 PM by K6BRN »
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N2DTS

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Re: Sherwood Engineering Receiver Test Data
« Reply #52 on: March 25, 2021, 08:36:49 PM »

Maybe the people that make the radio should test it?

Just off hand, it seems quite good to me (the hardware).
I have had most sdr's and besides the software, I do not see any real shortcomings.

A guy next door running a kilowatt? I can't test that, but I have some strong broadcast stuff that tears up the sdr play stuff and the mcHF rig.
The mcHF overloads but unless its really bad it mostly handles it well.
The discovery seems not to be bothered at all.
It also seems to be a very low noise receiver. Nice to listen to.
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W6RZ

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Re: Sherwood Engineering Receiver Test Data
« Reply #53 on: March 25, 2021, 09:44:13 PM »

Well - maybe someone here could create their OWN list with tested performance parameters...

Why bother? Nobody would take is seriously. I've linked the DC4KU test of the Airspy HF+ Discovery twice in this thread and nobody has said a word about it.

DC4KU has tested many receivers including the RSP's. Unfortunately, much of it is in German, but it's not difficult to extract the numbers. Check out his web page.

http://www.dc4ku.darc.de/
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K6BRN

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Re: Sherwood Engineering Receiver Test Data
« Reply #54 on: March 25, 2021, 10:51:02 PM »

Ron (W6RZ):

Quote
Well - maybe someone here could create their OWN list with tested performance parameters...

Quote
Why bother? Nobody would take is seriously.

Really?  All evidence points to the contrary, including Sherwood's success. 

If low-cost SDRs are the future (as opposed to $1K radios), as you've maintained, it sure seems that it would be worthwhile for someone with your passion and background to contribute by doing and posting some real work or even simply collecting, tabulating and presenting other's comparison data.

Or at least not discourage anyone else from doing so.

I'm pretty sure a consolidated, maintained and consistent list would gather quite a bit of interest.  Especially if it's format allowed an apples to apples comparison with Sherwood's list and clearly showed a convergence trend with mainstream radios ... presumably as the performance gap closes.  Frankly, it would create quite a sensational stir in the community if this trend were shown true and would no doubt prompt a strong response from equipment suppliers to improve the cost/performance proposition for radio amateurs.

In fact, it's very hard to find a downside to creating this list - all credit to the author, whomever that might be in the future.

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I've linked the DC4KU test of the Airspy HF+ Discovery twice in this thread and nobody has said a word about it

And ... why do we need to?  It's one test report, not a driving comparison that shows trends and prompts improvement, like Sherwood's list, which was the original topic of the thread.  So why comment?  There are a LOT of SDR dongles, and a comparison list could help capability growth and awareness just as Sherwood's list has for mainstream radios - that seems more than obvious.

I've read two of Werner's reviews (one simple eham commentary, one .pdf) and enjoyed them even if we have differing opinions.  Adam Farson (AB4OJ) has actually compiled many more reviews and he tends to be very non-judgmental - like Joe Friday on Dragnet, it's "Just the facts (and data), ma'am".  I like that  And Adam is consistent enough in his approach that a meaningful list could be compiled.  But, alas, not enough on DSP dongles. 

There's that opportunity to contribute, again.  All you really have to do is follow up.  And/or encourage someone else to.

Think about it.  Destiny calls.

Brian - K6BRN

« Last Edit: March 25, 2021, 11:03:13 PM by K6BRN »
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W6RZ

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Re: Sherwood Engineering Receiver Test Data
« Reply #55 on: March 26, 2021, 12:57:50 AM »

And ... why do we need to?  It's one test report, not a driving comparison that shows trends and prompts improvement, like Sherwood's list, which was the original topic of the thread.

I rest my case.
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N6YWU

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Re: Sherwood Engineering Receiver Test Data
« Reply #56 on: March 26, 2021, 08:40:26 AM »

Maybe the people that make the radio should test it?

There's a reason why many people prefer independent lab reports that compare equipment, over stuff that's been filtered by a vendor's marketing department.
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VE3WGO

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Re: Sherwood Engineering Receiver Test Data
« Reply #57 on: March 26, 2021, 09:30:58 AM »

plus, we can more directly compare radio performance results if they have been evaluated by the same lab under the same (or at least very similar) test conditions. Only an independent tester can achieve that.

On Sherwood's list, I have done was has been suggested a few times, ie copied it into an excel sheet and sorted it the way I want to.  That's because some operating conditions are quite different than close-spaced CW contesting situations, and having the other test conditions (wide-spaced interferers, for example) in the database is useful information too.

73, Ed
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K6BRN

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Re: Sherwood Engineering Receiver Test Data
« Reply #58 on: March 26, 2021, 11:36:33 AM »

And ... why do we need to?  It's one test report, not a driving comparison that shows trends and prompts improvement, like Sherwood's list, which was the original topic of the thread.

I rest my case.

Ron:

Good grief!

You make no sense whatsoever.  It's about a comparative list showing trends and relative performance, not a single report by itself.  And you know it.

Sherwood has already proven just how useful this approach is, whether or not you agree with the metrics and ranking on his list - it drives improvement.

I've rarely seen so many excuses to do - absolutely nothing.  Especially after blowing so much smoke.

This is a perfect opportunity to explore, promote and present data showing the advancement of the very technology you love, and do the community a big service in the process. 

Whether you do the work or someone else does.  Why discourage others when simply providing encouragement requires almost no effort at all?  Crimeny!

It seems that you prefer the role of armchair gadfly, which really doesn't generate much useful discussion nor does it provide any real data to debate.

OK.  You've made your role and position clear.  Time to move on.

Producing an "SDR List" similar to Sherwood's with tabular performance metrics (including cost) and tentative ranking would be a service to the community and could drive SDR evolution in the process.  Hats off to anyone who pursues this, it's a worthwhile effort.  And a lot of work, which is normal for any worthwhile project.

Brian - K6BRN

 

« Last Edit: March 26, 2021, 11:42:05 AM by K6BRN »
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N6YWU

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Re: Sherwood Engineering Receiver Test Data
« Reply #59 on: March 26, 2021, 11:52:12 AM »

The ARRL seems to publish tests of a lot of radios, big transceivers thru some small SDRs. 

Do they, or has anyone else compiled a comparative list of all the ARRL receivers test results?
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