HPSDR PureSignal and ANAN-100 Set-up and Demonstration (Pre-distortion)
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- Опубліковано 9 гру 2024
- Video demonstrating the setting-up and operation of OpenHPSDR's latest feature (Q1 2014) - PureSignal. This is a pre-distortion algorithm to actively reduce the transmitter IMD in real-time. It works very well!
IMD occurs when you mix two or more signals together - think two tone test - and of course the human voice has dozens of peaks, harmonics etc. and these added together in the audio chain of your radio result in dozens or more IMD spikes. PureSignal effectively reduces these on the fly by such an amount that the result is an IMD performance hitherto never seen before in amateur radio transceivers and makes this aspect of the transmitter the very top of the IMD tree!
One of the long term aims of amateur radio transceiver manufacturers is the implementation of predistortion to improve transmitter IMD performance which, since the introduction of solid state radios and 12v PAs, has not fared well. Apart from the Swiss ADAT SDR, currently this is the only amateur radio implementation of predistortion and results in superb IMD figures when correctly set up.
Very useful, especially for us beginners, thank you!
How did they achieve the same tap in such a wide band in a directional coupler?
Is there a strip line? And how is the compensation for the non-linearity of the frequency response done?
I am getting an Anan-10 and it does not have the "ext1" input. Do you know where the input cable would be attached to the Anan-10 for pure signal to work? Great tutorial videos by the way. 73, Tom, K2BEW
The ANAN-10 and 100 (in contrast to 100D) do not have an Ext1 input. However there is sufficient internal crosstalk for PureSignal to work just fine. If however you seek to add a PA after the radio, then you may need to provide your own mechanism to get the final waveform back into the radio (intentional RF ingress). This is tricky but not impossible. 73 HNY.
G7CNF Amateur Radio Station
Thanks for the reply, so if I understand correctly you just run puresignal on the Anan-10 with no external connections need for sending the signal back onto the radio, unless I had the external amp as you mentioned? Thanks and 73, Tom
Tom k2bew Yes, it may not work on 6m but most people seem to be getting good results running barefoot.
Good to know. Still learning about this great radio while I wait for it to arrive. Your videos have been very helpful. I found a video by Dr. Warren Pratt, NR0V, who invented pure signal that goes into detail how it works. Hope you don't mind my posting the link here, I think it could be helpful to others too. video.openhpsdr.org/HRF2014/PureSignal1.2.mp4
73,Tom , K2BEW
Nige, I have tried to set up PureSignal on my Anan-10 following your instructions and no matter how low from 31 and all the way down to "0" that I adjust the ATT the feedback level never changed from flashing red. I cannot get it yellow or green. Are there any other settings I should be looking at adjusting? Thanks and 73, Tom K2BEW
Family of: Coleman There a definite improvment. the offset in the imd is about 60dB with pure signal enabled, but the feedback level never stops flashing red. So I am hesitant to leave it turned on. It is a new Anan-10, any suggestions? Tom
Tom k2bew
Just wanted to add that I again did a reset of my database, and then ran through the puresignal setup as demonstrated by Nige, and I now am running in the green on my feedback, it is working great. Thank you Nige. 73, Tom, K2BEW
How can you set it up without a coupler?
If you do not intend to operate a linear amplifier (run barefoot) then you can take advantage of capacitive leakage inside the radio to accomplish PureSignal calibration - in fact you can even do this with the ANAN-10. One only really needs a coupler if one wants to include any subsequent PA stages in the PureSignal cleanup.