[TenTec] Orion V1 Code Analysis

[Merle Bone]

I recently got a copy of the ARRL 2007 Amateur Radio Handbook for reference. I was skimming the book when I ran into Chapter 16 - DSP and Software Radio Design - written by Doug Smith (KF6DX). Doug was a key contributor to the Orion V1 DSP code (Not the V2 code - which is very different). The Chapter does an excellent job of explaining the functionality and design approach used in developing the Orion V1 code - although the discussion is intended to be "generic." Although all of the chapter is very interesting, V1 firmware users will get a good look at the "Noise Reduction" approach in the discussion of Fig. 16.28 - An Adaptive Predictor. Page 16.28 gives a very good description of the two level AGC code and the very elegant AGC offset code used to eliminate AGC pumping from signals that are inside the roofing filter but outside of the DSP filter bandwidth. Page 16.16 gives a good description of the Speech Processing code, which yields some excellent speech processing performance. All in all, this chapter gives a very insightful view of the design and functionality of the V1 code. 

Doug does an excellent job of walking through the various aspects of the DSP based radio. He also did a nice job - all be it unfinished (But outstanding in performance) - of developing much of the V1 DSP code.
73, Merle - W0EWM