[TenTec] Orion Speech Processing Functionality

[Merle Bone]

The purpose of Speech Processing is to significantly increase the average to peak transmit power on SSB while not objectionably distorting the audio. The reason is that the human voice has a very low average to peak level ratio - often estimated at "one to ten." With that as the input to the transmitter, the average power output of a 1500W station will be somewhere around 150W, with occasional peaks at 1500W. Last night I was trying to work 4N6FZ from St. Louis, MO on 80M (World Series Rain Delay :-). Although I normally run firmware V1.373b5,  due to it having several areas of improved performance over the V2 firmware, yesterday I had loaded V2.059d in order to make some measurements (Looking at the reduction in audio levels at the headphone output and at the AUX audio output). Before calling the 4N6 I set the mic gain and then set the Speech processing to 5, which is where the audio starts to have a slightly "clipped" sound. I called the 4N6 and he came back to me. We then alternated 6 or 7 transmissions while he tried to get my call correct. He obviously had noise problems because he had a good signal in Missouri (I was receiving on a K9AY loop). He finally gave up and logged an incorrect call for me. With the SP setting I was using - limited by early distortion of the audio - I was increasing my average talk power from about 150W (No Speech processing) to about 250W  while having peak output power of 1500W (Alpha 87A). I needed Montenegro on 80M for the DX-Challenge so I decided to load V1.373b5 and try again. I set up the mic level and set the speech processing to 7 (Just before I start to hear any early clipping distortion in the audio). I called the 4N6 and he came back to my call (I was averaging about 400W average power with peaks at 1500W). He asked me to repeat my prefix and he had one letter in my suffix incorrect. I immediately increased the SP setting to 8 (Now I was hearing some early clipping distortion in the monitor audio) and my average power out increased to 500-800 watts (A 6 to 9 DB improvement in average talk-power). I gave him my call twice and a signal report and turned it to over to him. He immediately came back with my correct call and responded to the signal report I had given him.

Now 4N6 is not "long haul" DX from Missouri, but last night the conditions over the path on 80M were difficult due to his noise level (Some one came back and congratulated me for getting though from "West of the Mississippi" :-) and great Speech Processing made the difference between working the 4N6 and not working him. 

There were some improvements in the V2.059d release - and some new bugs - and the Speech Processing was improved. Because I do both SSB DXing and CW DXing, the performance of Speech Processing is important to me. For me, Speech Processing performance is increased talk-power with good audio. The Speech Processing in V1.373b5 was giving me 6 to 9 DB increase in average talk-power over no Speech Processing (Sometimes I see people set the mic gain way down so they can set Speech Processing on and still have good audio. Of course that often results in no real improvement in the talk power and maybe a loss in talk-power). The improvement in talk-power can be easily seen by changing the RF Power meter reading from "Peak" to "AVG" and then estimating the average position of the meter - not great precision but reasonable quantative accuracy. 

While the V2 code has made progress in performance since its release, it still has areas where it needs to be improved to match the V1 firmware performance -  such as the Speech Processing effectiveness. I have been running V1.373b5 in my Orion since I received the Orion back from Ten-Tec over a week ago (A number of upgrades done on the boards and the V2 mod installed and re-aligned), with the exception of an hour last night on V2, and it has run flawlessly (I typically have the rig on 12-15 hours a day). For a couple of years I had been seeing occasional stability problems (Using V1), such as when I used the voice recorders. However, V1 has been totally stable since the Orion came back. I don't know why, but I am very pleased with its performance and stability! I still look forward to a further improved V2 firmware release.
73,
Merle - W0EWM