When can we look forward to Pure Signal

G4BIM

Pure Signal

Al_NN4ZZ

Hi Peter,

See this conversation on adaptive predistortion.

https://community.flexradio.com/flexradio/topics/roadmap_inclusion_proposal

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com 

Barry N1EU

Thanks for posting that link Al - somehow I had missed that.  I certainly understand giving remote control a higher priority than predistortion but I feel a bit in the dark whether that means 6, 12, or 24 month wait for predistortion.  A 20dB cleaner tx signal is definitely important.

73, Barry N1EU

np2g

You are missing the result .its not just that IMD -30 or more down . it provides cleaner audio . Yes Predistortion reduces the IMD which directly impacts (reduces) distorted audio . I guess it's good for some to want to go remote.(A small percentage of users) But all of us ssb users would sound far better with predistortion implemented.

KY6LA_Howard

In a vote of US users at Dayton, Remote won by an almost unanimous majority. The same vote was about even at Friedrichshafen.

Paul Christensen, W9AC

We all know that R&D and programming resources are limited, and Flex must prioritize our want lists.  In addition to posting Roadmap features, I would like to suggest that Flex start thinking about posting non-Roadmap features.  For example, if adaptive pre-distortion (APD) is a paid subscription feature, it would be helpful to current and prospective owners to know that information now.  If it's a paid feature, then perhaps Flex could start assigning additional resources now to make the acceleration worth the effort.  I know this is easy for us to suggest and the reality is that development of paid features at this point may not be practical.  But I do hope it's something Flex will consider.    

np2g

Like I said Most are missing the resulting direct effect of Predistortion Or is it possible we are satisfied with communications sounding distorted .

Barry N1EU

My understanding, if correct, is that the main benefit from predistortion will be lowered spurious xmsn outside of the passband and less interference to adjacent frequencies (i.e., neighboring qso's).  I'm not sure there will necessarily be much audible improvement inside the transmitted passband.  I could be wrong, but I believe corrections are made at the transmitted RF envelope level, and not at the audio level.

Paul Christensen, W9AC

Although I cannot quickly find the data Barry, I've seen in the literature where the effects of APD on audio distortion is reduced by: (1) minimizing transmitted distortion; and (2) by minimizing transmitted distortion, decoded distortion in the receiver is also minimized -- and the latter may be responsible for a large part of audio performance improvement.     

np2g

OK the IMD products DO ,Does, affect the audio. It, IMD byproduct produces distortion. So besides reducing the opposite side band Another positive direct result is very clean audio . This IMD is one of the biggest complaints when you add a solid state amplifier So looking at your pan adapter you can see , and listening hear the results of Predistortion implemented

Barry N1EU

Makes sense, I'll add another thumb so now I've got two thumbs up for PD.  ;-)

Neal_K3NC

I am not quite sure why the poll should mean that predistortion should not go on the roadmap. When asked the same question, I also said "remote access" and the reason I did so was that it was a huge selling point for the 6000 series when it was announced. Flex promised it and they should deliver it. That doesn't mean that they do not need to do predistortion however. The competition offers it and the feature is very well received (pun intentded). C'mon and add it to the road map!

np2g

Pre distortion is being used by a privileged few right now Both Software and Hardware implemented .

np2g

Thank you for the clarification Pre distortion or whatever flex wishes to call it is a now reality . Not a promise But a implemented fact . You gotta step up or get stepped on

Barry N1EU

Excellent video presentation on PureSignal at http://video.openhpsdr.org/HRF2014/PureSignal1.2.mp4 - easily understandable explanation of how IMD enters the SDR picture at the amplifier stage and correction of the amplifier nonlinearities by Predistortion.  (the OpenHPSDR network delays described won't be an issue if Flex implements PD in the box)

np2g

great link Talk about having a positive impact to more hams. It is just a matter of time until even the knob guys have it.

G4BIM

I can understand that many Flex users would like the 'remote', thats fine, I suppose I am a bit old fashioned, I like to be with the radio and the linear in the shack, when I am operating.
It is a bit embarrasing that home brew constructors of the 'Hermes SDR' currently enjoy 'Pure Signal' technology, where we, with the best and most expensive SDR's do not have it as an option currently. So, back to my original question Gerald.... When will your loyal customers have it.... Give us a date + or - 3 months.

KY6LA_Howard

I think the issue comes down to available resources... which as we know are limited at a small company like Flex Radio.

Remote (LAN and WAN) is an easily understood "Killer App" from a marketing point of view which will drive a lot of sales to Flex.  This is especially true in the USA where Antenna Restrictions can make Ham Radio almost impossible without a Remote Capability.,...

While "Adaptive Predistortion" is a relatively hard to understand little known concept that only a few techno-nerds (like myself) are even aware of...or care about...

Until more people become aware of it, it will not be a "Killer App"  warranting the expenditure of limited resources before Flex fixes a raft of other issues such as the DSP, NB, etc, etc, etc.

Neal_K3NC

I am not completely sure I agree that the adaptive predistortion is a geek-only feature. I have one customer (very non-geek, hence why he is one of my customers!) who actually is thinking of selling his 6000 to buy the anan, solely because he is a phone only guy and the flex doesn't have adaptive predistortion on their roadmap. He says he can tell  user of Puresignal just by looking at their signal on the panadapter. He believes that the Puresiignal rigs sound "tremendous" and doesn't waste power in unwanted sidebands, hence it is a more efficient transmitter.

Geeky, yes but he believes its better in the areas he values most in a transmitter.

I believe this whole concept came from Flex 3-4 years ago (or at least cowboy Bob), it should be on the roadmap!

Al_NN4ZZ

Hi Howard,
Another potential factor that could influence the timing is the competition  When the ARRL, and Sherwood publish the IMD3 numbers for the 6000s and other competing SDRs that could make this more of a marketing issue.   ADP IMD3 numbers will be significantly better. 

The TX side of the equation in product reviews will likely get more emphasis as a result. 

(this is not so say the current priorities are not right, just another consideration that may influence the ADP timeline)

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com

G4BIM

Yes I agree Neal, if only from a Marketing standpoint it absolutely has to be on the roadmap, business and reputation will be lost without it...!!!
From technical point, its a 'no brainer' not to offer it. People will quickly learn about it, if only from the competition 'crowing' about it on air.

KY6LA_Howard

Don't get me wrong... I would LOVE Adaptive Pre-distortion... in fact Greg talked a lot about it in his presentation at Friedrichshafen.... 

I really loved the idea he presented of adding a sampler to the output of my Amplifier so that the Flex can also pre-distort my transmit signal to optimize the Output of my Amplifier and Radio..

Yes they could make a lot of people happy by putting it on the Roadmap..SSDR V2.1?  Yes it will drive sales to V2.1 software fees..

Notice on my roadmap it comes right after they get Remote LAN working in SSDR V2.0

Dave - WB5NHL

Many good comments. The impact of adaptive predistortion is maybe more bragging rights. Until a substantial number of transmitters have the feature the bands won't sound much cleaner.  Everyone should review Al's video link. Getting it right is not trivial! It might even be better to let others experiment and then implement when the algorithms/ specific parameters are mature.

BTW,  adaptive predistortion won't impact how a transmitted signal sounds and any wasted power is pretty low. Think about it - IMD3 already 30 db down ( a factor of 1000).  The "tremendous" is only preception. This is why people use double blind testing <grin>.

G4BIM

Great comments and discussion... thank you

Ken - NM9P

For me it is a matter of "diminishing returns" and "**** for the buck."  
I will enjoy it when it gets here, but for right now as a user running barefoot, the audio on my 6500 is already awesome and pretty clean compared to most other rigs out there.  I would much rather see the addition of CWX, FM, and upgraded DSP (NB, NR, APF, ANF) remoting, and improved interfacing/profiles, etc.first.  

Knowing that Flex's programmers only have so much time and energy, I feel that those features would give more added value before Adaptive Predistortion.  

However, I think from a marketing and customer satisfaction standpoint, It would be nice to have it on the roadmap SOMEWHERE, even a year off, so that people can know it is coming.

Gerald-K5SDR

As stated previously, we do plan to implement pre-distortion but it falls behind LAN & WAN networking in priority.  We agree that the feature has value and will implement it when it comes up in the priority queue.  It is premature to put it on the road map because we want to make sure we meet all our currently published commitments.  Note that we are the first and only Ham Radio company we know of to publish a public software road map.  

Ken - NM9P

Thanks Gerald.

Neal_K3NC

This is why I stay a Flex fanatic, the transparency, quality and honesty of the company stand alone in the ham market.

Michael - N5TGL

I'm still waiting for that first contact that says "Oh my god, your signal is so distorted I can't talk to you...if you only had predistortion we could have a QSO."  Or "Oh my god you are splattering all over the band."  I find particularly amusing the TX efficiency improvement.  Sure, there will be an improvement...but will it even be detectable under real-world use conditions?  To get 1 S-unit, power needs to be quadrupled.  To get a half a S-unit, power needs to be doubled.  People would be far better served by doing any sort of antenna improvement then they'll ever get from predistortion.  As for folks who talk about emissions outside of the TX passband, they meet FCC required specs, just like any other radio.  In fact, I've had unsolicited comments like "I heard your signal and it was so clean on the scope and to my ears I knew it had to be a Flex."  This was with me running into an Ameritron ALS-500M solid state amp...OH NOES THE DISTORTION *eyeroll*

If people feel they need to buy an inferior (IMHO) radio to get predistortion, so be it.  I think  predistortion is a great idea.  I really like the way that they intend to implement it which was shared at Friedrichshafen.  Yep, I'll pay for feature and the additional HW to make it work properly.  However, I think there is a problem with perspective here and how much benefit it will actually bring.  
So I ask the following in terms of how much revenue it will bring to the bottom line of Flex.  Which do you think will generate the most sales?:

1.  Predistortion

or

2.  Fully internet accessible 8/4/2 RX direct digital sampling SDR transceiver

Probably doesn't take a rocket scientist to figure this one out.

G4BIM

I hear and understand all the comments and observations surrounding Pure Signal.

However, the fact remains that this may be a bad marketing error especially as we seem to have this feature already built into the hardware.

It has allowed another manufacturer and home builders to gain an advantage on FlexRadio.

Taking into account the big price differential, there will for sure be potential customers who have opted for the competitions product, having been influenced and impressed by this apparently significant feature.

Yes I know its only marginal in practical technical terms but.... People are very easily impressed by features which at first sight seem a bIg deal.

W9OY

I hope flex takes a little time on implementation. It seems to me this could also be extremely useful on some digital modes. Also a well thought out algorithm could probably be used to predistort noise out of received audio. I'm also very much a fan of a probe placed on the amplifier output to yield a systemic reduction in distortion. With good engineering you could leap frog the present pure signal technology with something far superior 73. W9OY