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Author Topic: Adaptive Predistortion on the ANAN radios  (Read 14264 times)
VU3WJM
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Posts: 1




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« on: December 24, 2013, 12:00:39 AM »

Finally clean transmit from a modern day radio, this seems like groundbreaking work from the OpenHPSDR group & Warren, NR0V,  -50dB IM3 on a 13.8v 100W PA:

http://groups.yahoo.com/neo/groups/apache-labs/conversations/topics/8844

73,
VU3WJM
Rahul
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PJ2BVU
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Posts: 112




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« Reply #1 on: December 24, 2013, 02:40:26 AM »

Zenki will get one.  Grin

Jean-Claude PJ2BVU
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WD5GWY
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Posts: 391




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« Reply #2 on: December 24, 2013, 09:53:00 AM »

I certainly want one!!
But, I doubt that Santa has one in his bag for me.  Sad
Maybe next year.
james
WD5GWY
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W4OP
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Posts: 393


WWW

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« Reply #3 on: December 26, 2013, 01:10:25 PM »

Finally clean transmit from a modern day radio, this seems like groundbreaking work from the OpenHPSDR group & Warren, NR0V,  -50dB IM3 on a 13.8v 100W PA:

http://groups.yahoo.com/neo/groups/apache-labs/conversations/topics/8844

73,
VU3WJM
Rahul

Hardly groundbreaking,The ADAT 200A has used adaptive predistortion for over 4 years now:
http://www.adat.ch/index_e.html


Dale W4OP
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KC8IIR
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Posts: 57




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« Reply #4 on: December 26, 2013, 06:52:10 PM »

That's great, now the Anan is the 1st radio to do it with 100 watts of power.
 sorry Dale, they had to be first some how.
 Grin Grin Grin Grin



Hardly groundbreaking,The ADAT 200A has used adaptive predistortion for over 4 years now:
http://www.adat.ch/index_e.html


Dale W4OP

Greg kc8iir
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W4OP
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« Reply #5 on: December 27, 2013, 06:05:30 AM »

I agree Greg- although I am not an owner, I really admire what they are doing.

Dale W4OP
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ZENKI
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Posts: 906




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« Reply #6 on: December 31, 2013, 11:02:21 PM »

Good news a step in the right direction. Now where are all the hams who said it was going to be too expensive and the end of  ham radio as we know it.

Hopefully now hams will now say the Anan has -50db 3r order distortion why has my 8000 dollar radio have -23db 3rd order distorntion. I did not expect to buy a radio
that costs 8000 dollars that performance like a 50 dollar CB radio.

At the end  of the day if the ham radio manufacturers did their job properly there would not be any need for predistortion technology.
All they have to do is:

1. Select proper RF Fets that have low IMD performance to begin with.
2. Make sure their transmitter dont use ALC as a form of compression or just eliminate ALC on TX altogether.
3. Make sure the transmitter can deliver its rated output with going into compression.

Since all the current manufacturers use the above cheap design shortcuts to short change hams it might be a while before they realize the errors of their filthy design
techniques. Just changing most  radios PA's  to better RF FET's that can deliver about -40db 3rd order and deliver a design without ALC compression will result in radio that
is as good as pre-distortion PA in the real world

I will buy any radio with clean transmitter and a very good receiver. I will not buy a radio with high receiver while the transmitter sucks like the Flex6000.
While I own a Hermes I have my own homebrew PA that has excellent -40db 3rd order distortion. Predistortion will make my Hermes one of the cleanest  ham transmitters around. The Anan Team should be congratulated for taking the bold initiative of implementing predistortion rather than coming up with excuses like many hams  and manufacturers who  just think thats its all too hard. Real hams have delivered leading edge technology and hopefully hams will start complaining to other manufacturers about the poor state of their radios transmitters.
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KC9XG
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« Reply #7 on: January 04, 2014, 07:16:11 AM »

I have an Apache-Labs ANAN-100D and am a beta tester for the OpenHPSDR PowerSDR Pure-signal/Pre-distortion software.  My barefoot results show IMD3 has improved from -28/30dbc to -48/-52dbc. 

Not much required of the barefoot ANAN-100/D operator except to adjust "ATT on TX" attenuation level to secure the proper feedback level for the PureSignal/pre-distortion software.

Bill KC9XG
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W9AC
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Posts: 53




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« Reply #8 on: January 12, 2014, 07:47:20 AM »

I have an Apache-Labs ANAN-100D and am a beta tester for the OpenHPSDR PowerSDR Pure-signal/Pre-distortion software.  My barefoot results show IMD3 has improved from -28/30dbc to -48/-52dbc. 

Not much required of the barefoot ANAN-100/D operator except to adjust "ATT on TX" attenuation level to secure the proper feedback level for the PureSignal/pre-distortion software.

Bill KC9XG

Bill is right - and this is not vaporware.  It's real and working on the air right now.  For users with the new PureSignal algorithm, I'm measuring opposite sideband suppression with shoulders down better than -50 dBc from f0.  As I recall, at least one user is now sampling PureSignal after his homebrew amp so that linearization occurs as a complete RF system. 

In the last decade, we have been successful in getting manufacturers to pay attention to three key areas of needed improvement: (1) CW key clicks; (2) Rx close-signal handling; and now (3) Tx IMD performance.   

Despite the Internet and competing multimedia technologies, there's never been a better time to be involved with amateur radio.   Imagine what what our SK predecessors would think if they could see the ANAN, Flex 6K, and SunSDR2 in operation.

 

 



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AC2FO
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Posts: 2




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« Reply #9 on: January 15, 2014, 10:18:28 PM »

This ham (AC2IQ)  has homebrewed his own transmitter and has been using pre distortion for at least 4 yrs it is also analog, not digital. Very impressive.
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NO9E
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Posts: 383




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« Reply #10 on: January 18, 2014, 05:55:10 PM »

Is there any way to adapt predistortion to include an amp?
Ignacy, NO9E
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KC9XG
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Posts: 18




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« Reply #11 on: January 19, 2014, 10:40:47 AM »

Ignacy,
    You can add an external coupler to the output of the amp and feed the attenuated sample back to the receiver for OpenHPSDR PowerSDR PureSignal pre-distortion processing.  This is the preferred method when using an external amplifier, but some beta testers have reported good results using the ANAN-100 / ANAN-100D leakage sampling (no external coupler), with an external amplifier.  I am aware of one example of this where IMD3 from the ANAN-100 + amplifier, as measured with a separate receiver and antenna, reportedly went from about -30dbc to -45dbc .  YMMV

Bill KC9XG
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KC9XG
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« Reply #12 on: January 19, 2014, 05:31:45 PM »

I have done a review of the OpenHPSDR PowerSDR PureSignal adaptive pre-distortion beta version.  The reviews includes drawings showing the ANAN-100/D with an external amp / coupler and the barefoot ANAN-100/D. 

The Review of PureSignal optimization can be viewed at http://www.n9vv.com/N9VV-Apache-Labs.html#KC9XG

Bill KC9XG
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NO9E
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Posts: 383




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« Reply #13 on: January 21, 2014, 10:41:00 AM »

Can predistortion increase the efficiency of linear amps? Lets say that an amp produces 1500W saturated but is used at 1000W for linearity. Can we drive the amp to 1300 or 1400W, with preedistortion improving the linearity to an acceptable level? Is driving accurate enough not to cause saturation peaks?

Perhaps with tube amps, one question is how to account for fluctuating HV.

Ignacy, NO9E 
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KC9XG
Member

Posts: 18




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« Reply #14 on: January 23, 2014, 06:51:44 AM »

Ignacy,
   No idea about efficiency increases. 

Warren Pratt, NR0V has stated: "Our predistortion algorithm is "adaptive" meaning that it is designed to
automatically compare the input and output of the amplifier and repeatedly calculate and optimize the
correction."

It seems likely it will handle tube amp HV supply fluctuations, provided suitable and effective sampling methods are employed at the output of the amplifier.

Bill KC9XG
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