[hpsdr] OpenHPSDR suitable HF Amps
phil at pharman.org
Thu Jan 17 17:15:31 PST 2013
Yes, that would be the case assuming the drive signal was also perfect.
It would be delivered by Santa and packed by the tooth fairy.
There are a number of HPSDR members working on adding pre-distortion to
our hardware and software.
Whilst in theory its simple enough, measure the system non-linearity and
then apply the inverse to the drive signal.
However, its not that simple in practice since the system non-linearity
changes with frequency, power level, SWR, temperature etc. These is also
an issue called Memory Effect where the non-linearity changes dependent on
the level of previous signals.
It also appears that pre-distortion can't be applied to just any old PA
stage. In particular it needs be designed initially to minimize Memory
That being said, results so far have been very encouraging but that does
not necessarily mean that pre-distortion software can be added to existing
HPSDR software without hardware changes.
> ***** High Performance Software Defined Radio Discussion List *****
> SO, would an amplifier rendered perfectly linear through theoretically
> perfect pre-distortion compensation no longer generate IMD or harmonics,
> & therefore no longer need low pass filters??????
> wb4gcs at amsat.org
> On 1/17/2013 2:39 PM, AA8K73 GMail wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>> TeamSpeak has been carrying reports on the pre-distortion amplifier
>> experiments. This could produce quite a clean signal.
>> Mike - AA8K
>> On 01/17/2013 06:47 AM, Berndt Josef Wulf wrote:
>>> ***** High Performance Software Defined Radio Discussion List *****
>>> I was surprised to find out that Apache-Labs no longer sells the
>>> kits nor the enclosure. What gives Abhi?
>>> Now this begs the question how long before we see Apollo or Munnin? Do
>>> we have an ETA for either of these amplifiers?
>>> I have several amplifiers that would be suitable to interface with
>>> Hermes, but neither have the form-factor for a man-pack design.
>>> 73, Berndt
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