Adaptive pre distortion on a 6500

Ed baker

Yes the rumors are true Adaptive predistortion while using a 6500 was heard on 75 K2WS ALAN Congrads . Hardware version right on. Great signal great imd Straight line signal. And just think you didn't have to beg to get it. Do hope you offer it to all

Peter K1PGV

OK... I'll say it: I don't understand a single thing in this post. Well, I know what ADP is... But beyond that. Could the OP perhaps post something a bit more clear, to avoid our having to guess what he means? Peter K1PGV

Reg

Peter:

It is actually a very clever process.  If you have a transmitter driving an amplifier, then the amplifier is going to introduce some distortion into the transmitted signal because it is not perfectly linear.  Now if the transmitter samples the amplifier output and distorts (yes, distorts) the transmit signal in a manner such that the amp distortion results in a perfect signal then you have adaptive pre-distortion.  The process is sometime called "adaptive pre-distortion" and sometimes referred to as "pure signal."

Quite some time ago Steve posted that it was not a top priority at the moment but they would eventually get to implementing it in SmartSDR.  No timeline.

Reg

KY6LA_Howard

I believe many of us understand what ADP purports to do (I posted how Warren described how he made it work at Friedrichshafen 2014) but I am with Peter in being unable to understand what exactly Ed is talking about or how it might have been accomplished.

Jim K4JAF

Yes, the post is somewhat cryptic and lacks details..  Please supply more details please.

Jay Nation

Why the secrecy?
73, Jay - NO5J 

Martin AA6E

At Dayton, FRS said that they had polled us users about APD/"Pure Signal", and only a small minority said it was important to them.  Many people may not know what it is, of course.  But the main beneficiary of super linear transmitters is everybody else on the band.  I.e., you're being kind to your fellow ham.  Good for you, but don't be surprised if not everyone is keen to spend money or development time on it.

Ed baker

No secret
I have written ,requested ,talked about pure signal sooooo!!! many times i just took for granted that someone actually was reading .

Reg,s description is pretty good .

Now this event was done with the 6500 Flex and hardware , the anan uses software . There were also 3000 and 5000 flexes using hardware to accomplish this pure signal.

Results
IMD 3rd order -50 , -60 , -70DB , down.
With no excuses just clean transmitted energy .

If you sample and include the amplifier both the radio and amplifier will exhibit this similar trait.
When you look at the signal on a panadapter you will see the straight line going from the noise floor right up to the max signal. unlike any any radio out there without this adaptation .

So there is now a 6500 flex out there running a hardware version of pure signal FANTASTIC .

There was no begging to implement , just a judicious dose of pure ingenuity . Hardware or software this is a beautiful way of making a transmitted signal CLEAN .

For me I use Pure signal every day (Software ,external sampler, . and now a 6500 user can also .

ALAN again what a accomplishment WOW a hardware preview of Version 2,000 or whatever . For all who don't want to produce a clean footprint We know who you are

Peter K1PGV

So, I think you're saying:

"Alan K2WS, a clever guy who's been involved with Flex SDRs since the Flex-1000 (remember his OXCO mod?), has managed to perform hardware modification to a Flex-6500 to implement ADP... and you like it.  A lot."

Did I get that right?

Maybe Alan will be making a mod kit available?

Peter
K1PGV

Ed baker

No secret I have written ,requested ,talked about pure signal sooooo!!! many times i just took for granted that someone actually was reading . Reg,s description is pretty good . Now this event was done with the 6500 Flex and hardware , the anan uses software . There were also 3000 and 5000 flexes using hardware to accomplish this pure signal. Results IMD 3rd order -50 , -60 , -70DB , down. With no excuses just clean transmitted energy . If you sample and include the amplifier both the radio and amplifier will exhibit this similar trait. When you look at the signal on a panadapter you will see the straight line going from the noise floor right up to the max signal. unlike any any radio out there without this adaptation . So there is now a 6500 flex out there running a hardware version of pure signal FANTASTIC . There was no begging to implement , just a judicious dose of pure ingenuity . Hardware or software this is a beautiful way of making a transmitted signal CLEAN . For me I use Pure signal every day (Software ,external sampler, . and now a 6500 user can also . ALAN again what a accomplishment WOW a hardware preview of Version 2,000 or whatever . For those who dont want it We know who you are

Jim K4JAF

Still no details on how "pure signal" on the 6500 was accomplished.. 

Details please, your so cryptic in your answers..

Ed baker

please read
It was done with a hardware package attached to the 6500 . It emulated the compare and re config in hardware .

If you wish the exact details ASK ALAN I listed the call.
He may share it with you .

II guess you can also ask Flex FYI there are many Hams who have contributed to this Pure signal event. It is just really great to see a 6500 using this function

Bill -VA3WTB

Gerald already said the radio is set up for pure signal a long time ago, this shows he was right. Something to look to when flex finally does it.

Ed baker

Actually I really don't like to post here. And if it wasn't a 6500 I never would have . See It is pure innovation . And BILL I'll be as kind as I can " Its questionable on FLEX ready ." I had a good laugh on that one . So please excuse me I,m on Island time here .

Richard McClelland, AA5S

Periscope up.  Another pre-distortion controversy.  Periscope down.

Bill -VA3WTB

Since Flex has been truthful in the past, I will accept what Steve said, it is already set up for pure signal, that's why it's working. And it won't need a crummy add on box to do it.

Steve - N5AC, VP Engineering

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Official Response

When we designed the FLEX-6000 we had adaptive predistortion in mind so we included a tap from the transmitter that feeds back into the receiver. This gives us simultaneous access to the desired and actual transmit spectrum in the FPGA so that we can implement linearizarion. We also have sensors for temperature, voltage and load match of the PA as these can be used to improve linearizarion. The work that needs to be done for the FLEX-6000 is to experiment with algorithms and input sources to determine what gets us the most **** for the buck and then finalize the implementation.

The FLEX-6000 already has the highest precision DAC of any amateur transmitter and excellent IMD numbers so we decided to focus first on features that the community is waiting for and return later for implementation of predistortion. Predistortion in the cellular business is critical because they are putting many carriers in a single PA and spectral purity when you're doing this is critical. But for ham radio, it is more of a "nice to have" and "nice neighbor" sort of thing -- it's not going to prevent someone from copying YOUR signal and the FLEX-6000 spectral purity is well above the legal limits. Barring significant hype that makes this a marketing issue, we'll look into this after finishing the items on the road map that you, our customers, have told us are important for you.

Since we thought ahead, you will not need to use an external device to tap the actual transmit signal and feed it back into the receiver when the time comes. Incidentally, our VP/GM of our government business, Graham KE9H, has considerable experience with predistortion having run a company that focused on predistortion in cellular PAs. He also developed PAs for HPSDR.

Bill -VA3WTB

All that said,,Nice work Allen, I wonder if someone will build this box and sell them to people who want one?

KY6LA_Howard

Flex has an Open API...

Without getting into the details of how to implement ADP, I would suggest that if there really is so much pent up demand for ADP, then perhaps some third party could write the software to implement it using the existing hardware taps that Steve identified.


OTOH.. if as I suspect that it is a "Nice to Have" feature and since no third party seems to be rushing in to write the ADP Software then perhaps we will have to wait for Flex to get around to it sometimes after V2.0 WAN and other necessary features which have a huge "Need to Have" demand

WA6FXT Mike

AMEN, to that!

73's

Walt - KZ1F

I was not aware there even was a rumored sighting of a 6500 running apd on 80 mtr the other night. If it doesn't even exist, my guess is the 'rumors' were false. Why is there such a 'clamor' for 2.0 WAN when it appears those wanting to work remote already are?

Ed baker

Actually I would hope everyone copied my signal There was growing pains involved .A large amount of fellow hams helped . And no one should stop were hams are now Call it Progress. Driven by innovation , Experimentation and really great gifted people not sitting on their hands and minds Finally someone actually recognized and thanked ALAN , Thats what the post was about . Not please ,Pure signal . Not even a discussion about it . So hats of to Dave Alan Doug Gerald and about 1000 others for actually building implementing a system that produces a cleaner signal. By the way Software for this function being implemented into a LOCKED system It Wont Happen by a 3rd party vendor What a laugh If it's pure signal in software has to come from Flex Oh yes !!!! A complete closed loop control is prefered . Not just in the box (Including any AMP )

K1UO Larry

It will be so funny to hear all the chimes of "wow", "this ADP is awesome"  and "why didn't they do this sooner"" come out after a few more version releases of SSDR.... It appears that everything is relative after a period of time and research.

Ed baker

Keep you fingers crossed. Spin around a few times. And drink lots of water. Yes it will all be better

k3Tim

I tried this, it didn't help.
Please advise

Ed baker

Did you click your heels. 3 times????

KY6LA_Howard

Because running rWAN via VPN is a kludge. A sit does not solve the major issue of running WAN without a PC attached to the 6000 when the 6000 is located remotely.

KY6LA_Howard

The API is OPEN Third Parties are developing all sorts of useful software. Already.

Ed baker

Warning warning. Cud a is out there. In test.

Ed baker

Gee I think I'll make the buttons red. If you want innovation package the software and lease development packages. Then stand back

Bill -VA3WTB

As flex is already set up for pure signal as Steve said, and they already know how they will implement it.  Why don't the pure signal community do the same with an Icom, now thats doing something....since the flex is already pretty clean.

Ed baker

Look. It's simple. Some never want improvements. And some embrace Progress. Let no one stand still because you will be run over.