[TenTec] V2.062a Speech Processing

[Merle Bone]

Although the Orion V2 code still has some problems/issues with performance, one area that appears to have been addressed in the V2.06X releases is the speech processing performance. Earlier versions of the V2 code suffered from a combination of audio distortion and weak, if any, compression. The V2.06X releases clearly sound like the distortion has been addressed and that the compression is much improved. I recently bought an LP-100 Digital Vector RF Wattmeter from Larry (N8LP) http://www.telepostinc.com/lp100.html . Among the many functions provided in the LP-100, Larry recently added new code to allow the user to measure the "effective audio compression" of a transceiver. The technique uses an audio test tone pattern ( the one I used had a 1KHz tone with alternate 50MS time segments with the levels 20db apart).
The RF power meter samples the power level 40,000/second to generate average value. I used an "audio sound power meter" to measure the audio level of my voice calling DX and then used the sound power meter to set the test tone to the same level (Using a single level tone) into the microphone.

I tested the V2.062a code and got the following results:
Proc Setting               Audio Result                                    RF Result Average Power
Off                                    Slight Expansion                            ~8W
1 - 4                                  Close to no Compression               ~9-10W
5                                         ~5dB Compression                      ~12W
6                                      5-10dB Compression                      ~13W
7                                       ~10dB Compression                      ~16W
8                                     10-15dB Compression                     ~20W
9                                     15-20dB Compression                     ~26W 

I tested the V1.373b5 code and got the following results:
Proc Setting                Audio Result                                    RF Result Average Power
Off                                     Slight Expansion                             ~8W
1 - 4                                    Close to no Compression              ~9-10W
5                                         ~5dB Compression                       ~12W
6                                       5-10dB Compression                      ~14W
7                                        ~10dB Compression                      ~17W
8                                      10-15dB Compression                     ~24W
9                                      15-20dB Compression                     ~31W

In all cases the peak power stayed very close to 39W - which is what I use to drive my Alpha 87A to 1500W peak output.

As you can see from the results they track very closely - so closely that they almost look like the same algorithm! There is a slight difference at the 9th level on the Speech Processing but it is very minor (And might be altered if the mike gain were increased). At a Speech processing level of 7 the talk power is doubled from the level with the Speech Processing off. At the 9th level there is roughly a 6dB (1 S-Unit) improvement in the talk power of the rig. I usually stop at eight but there is no audio "background noise level increase even at 9 (Maybe a very little hum). The audio sounds very good in the monitor and the quality was verified by a friend. The talk power improvement is very important in trying to work SSB DX.

I think the Orion V1 code has the best Speech Compression I have ever seen in an HF radio and now it appears that the V2 code matches it! Thanks Ten-Tec!
73, Merle - W0EWM