[hpsdr] EER finals, predistortion

[Phil Harman]

Hi Ben,

The openHPSDR Penelope exciter was designed to enable predistortion to be added when required.  It provides an ADC input that could take the envelope of your transmitted signal and compare it  with the envelope of the required signal  i.e.  Sqrt(I*I + Q*Q).

The envelope of the output of Penelope is already available at the output of  the ADC (U16). I did some initial test some time ago but the IMD performance of Penny is very good and does not benefit from adding predistortion. It did indicate that the technique is feasible and I'm sure would improve the performance of a subsequent PA stage. 

The ADT-200A  (http://www.adat.ch/index_e.html) does use adaptive predistortion very effectively.

73's Phil...VK6APH 
  ----- Original Message ----- 
  From: Ben Witvliet 
  To: hpsdr at lists.openhpsdr.org 
  Sent: Friday, July 23, 2010 6:24 PM
  Subject: [hpsdr] EER finals, predistortion


  ***** High Performance Software Defined Radio Discussion List *****




------------------------------------------------------------------------------


  Dear all,

   

  I found the following (commercial) publication on very high efficiency RF power amplifiers:

  http://www.mathworks.nl/company/newsletters/digest/2010/july/nujira-amplifier-performance.html?s_v1=13445411_1-6XCKGU

  It is of course a success story describing the benefit of their own product, but the message I get from it: EER as we meant to achieve in Thor can be done. 

   

  Also the article mentions the use of predistortion to create a very linear amplifier. I heard that before from an English consultant (For my QRL I participate in European standardization work). He said that mobile phone network operators had great success with predistortion to get rid of IMD products on combined installations. So I see the remark in this document as a confirmation that that has become feasible with "average" means. I haven´t seen any amateur publications yet on the use of non-linear or not-so-linear amplifiers and predistortion. With the processing power we have in HPSDR this may come within reach.

   

  By the way: as a MatLab user I'm very interested in using Simulink to simulate such applications. Makes it possible to replace the MatLab software blocks bit-by-bit by real-life hardware.

   

  Justed wanted to share this information with you.

   

  Kindest regards, 73,

  Ben, PA5BW



------------------------------------------------------------------------------


  _______________________________________________
  HPSDR Discussion List
  To post msg: hpsdr at openhpsdr.org
  Subscription help: http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
  HPSDR web page: http://openhpsdr.org
  Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/


------------------------------------------------------------------------------



  No virus found in this incoming message.
  Checked by AVG - www.avg.com 
  Version: 9.0.851 / Virus Database: 271.1.1/3021 - Release Date: 07/22/10 14:36:00
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20100725/fb2c9ba6/attachment-0003.htm>