DSP - ANF Performance Specification

Lionel

ctate243

Jim Gilliam

ctate243

Bill -VA3WTB

Chris, I understand what you just said and I understand the thread, But bare with me a bit please.

If I understand things that Gerald said in the past, is that Flex is doing the DSP funtions very none conventional. They were developing something no one else was doing, as an example, wide band DSP coding. I would imagine Flex is keeping their work guarded?

So then, how can we be sientific and staying within the focus here without really understanding just how Flex is even aproaching this?

Robert Lonn

Geoff AB6BT

I don't believe we need to know the algorithms or topology used internally. Just consider it a black box function. Define what you want it to do and leave the engineering of how to accomplish that function up to Flex. 

ctate243

I couldn't have said it better myself.

Bill -VA3WTB

Sorry I must have misunderstood you Chris

Lionel

James Whiteway

Chris, one sure way to test the ANF is to listen to some of the roundtables on 75 and 40 meters on Friday and Saturday nights! Plenty of jamming tuner uppers to test against. And lots of kilowatts too! :-) Seriously, the issue can be reproduced tuning an amp into a dummy load with one radio on the same frequency as a qso in progress on another radio hooked to an external antenna. Or even using a signal generator in place of the second radio and amp(and dummy load) That will reproduce the blowby that happens with a strong carrier tuning on top of a qso. No setting I have tried to date with the ANF will stop the offending signal from popping thru the top of a conversation one is trying to monitor. The closest thing to helping is dropping the AGC-T all the way to zero. But, even then blowby can happen. The Icom 7300 and several other radios I have or had, handle the situation with ease. That's what frustrates me. A $5,000.00 radio cannot do as well as a $850 radio on such a situation as this. I would have thought it would be just the opposite, but it's not. Other than that and a few other issues, the 6600M is a great radio. But, it's a shame this issue has continued from v1.x til v3.x. My sincere hope is the basics are fixed in all three versions of SSDR. Had I not traded up to the 6600M, I would, in all likelihood, would have still been on v1.x till multi client(aka MultiFlex) came along. James WD5GWY

Lawrence Gray

HCampbell WB4IVF

“The ANAN NR and NR2 features basically eliminate noise without having a noticeable effect on the audio.  The NB and SNB features remove various  periodic noise without having a noticeable effect on the audio.”

But another ANAN user says:

“it amazes me how there's so much difference in the results of noise testing. Scott swears by NR2 whereas I have only once found it to be effective - generally it won't work unless the signal is strong and there isn't random noise like storm crashes, in which case I wonder why use it?  SNB also does nothing for me other than change the pitch ... i've never seen a case where it improved S/N. I guess everyone has different results ... of course I'd think that would not be the case, that sometimes, once in a while, we'd all see some benefit if anyone of us is seeing a benefit. go figure.”

https://groups.yahoo.com/neo/groups/apache-labs/conversations/topics/36995

Yep, go figure.  (-:

Dan KG0AQ

Bill -VA3WTB

We need to be carful in comparing the Flex DSP to other radios. Flex is doing the DSP in a much different way then other radios. Most modern radios do not do DSP 100% in software, they combine hardware filters with software.

The Flex DSP is wide band filters, the Anan is not. You can't do wide band in the PSDR platform.

The problem for Flex is, they are inventing every time they touch the DSP filters, they have nothing to really compare with SSDR.

Robert Lonn

So I was on 20 meters about an hour ago.. While listening to this W2 in New York here in California,, a strong carrier popped up within the 2.3 KHz Bandpass, looked to be about 1.1 KHz away, someone tuning up his TX.. I hit the ANF and , boom, it was gone while the W2 was still readable.. I think that tells me everything is working fine!!! The W2 was a S5, the tune up was a S-9,,  Robert

Dan KG0AQ

Why do we need to be careful? I understand the electrical differences between SDR and IF based radios  One works with ANF and the other one doesn't. Why do some people around here tiptoe through the tulips? It's a hobby and a radio company. I can wait for a fix.

Bill -VA3WTB

Because we are not comparing the same things. yes it may be true, black and white, it does not work as well as this or that radio. But the DSP is created much different then another radio lets say, that should be considered.

Even some of the other SDR radios do not do DSP 100% in software, so then what would we compare?

Dan KG0AQ

On weak signals and low noise floors the ANF works...ok. Go above S9 with a SSB signal and it falls apart.  Try listening to 40-160M tonight and post your thoughts.  73

Lionel

Dan, I'll try it on 75 this evening. Robert's experience above indicates it works when the intended signal is much lower than the carrier, as you also point out.  So is it reasonable to say that at some point, unknown, the ratio, signal to carrier, "breaks" the ANF; I think it is but at what point and if we reversed the ratio, does it still fail?

I have good signal generator and if I can find a combiner around here it will be an interesting experiment.  Maybe someone else in the community can try this.  I suspect Flex has but maybe in the lab and not in the adverse conditions we routinely encounter; not much value in replicating a lab test.

Has anyone ever used the ANF on multiple carriers? Does it work? Is it supposed to work?  

Lionel

Craig Williams

I agree but I was flamed in the community for my comments.

ctate243

Bill -VA3WTB

Lionel

Craig Williams

Finally an actual measurement. What a relief.

Gary Schulz

Burch - K4QXX

Joe N3HEE

Have you identified the actual noise source that your WNB works with ?  I have not seen any improvement at all with WNB turned on.  I suspect it only works on a very limited number of noise types ?

Burch - K4QXX

My issue is with powerline noise.  I have a buzz sound on most HF bands.  It gets really bad when it's dry outside.  Once the summer rains come and clean off the lines here in Florida, my noise gets better.  Before flex added the WNB, some days I couldn't use my flex and had to use another radio.  The WNB has done wonders to my situation.  That said, the two NBs on my old Flex 5000 worked better than the WNB on the 6000.  But the WNB was a huge improvement for my type of noise.

Mark K1LSB