[TenTec] Orion II Questions

Billy Cox aa4nu at comcast.net
Sun Dec 21 13:48:56 EST 2014

Excellent work Barry, Thanks for the follow-up on this!

Perhaps the 8 dB audio difference could be addressed in a
future firmware update ... (For your notes John Henry?)

MC es HNY to all!

73 de Billy, AA4NU

----- Original Message -----
From: "Barry N1EU" <barry.n1eu at gmail.com>

I just wanted to report back on a few measurements I was able to do with
limited test equipment.  I confirmed that "AGC Off" is a misnomer - DSP AGC
is fully active at the "off" setting.  There is no "AGC Off" in the Orion.

I confirmed that the AGC slope function is working as intended.  However,
there is one "minor" issue - the Orion audio output level with "Flat" slope
is about 8dB higher than with other settings.  So if you're listening to a
signal and flip the slope setting back and forth, you might get thrown off
by the sudden increase in volume at "Flat".

73, Barry N1EU

On Sat, Dec 20, 2014 at 4:23 PM, Barry N1EU <barry.n1eu at gmail.com> wrote:

> That's correct.  "AGC Off" in the Orion is just very fast AGC.
> Also, under all conditions, hardware AGC kicks in at about s9+20dB to
> prevent overloading the ADC.
> Barry N1EU
> On Sat, Dec 20, 2014 at 3:46 PM, Kim Elmore <cw_de_n5op at sbcglobal.net>
> wrote:
>> I think the problem with that approach is that you can't truly turn off
>> the AGC in the Orion II. At some level, it is required for parts of the
>> DSP. I'm not sure what happens when you select "off" for the AGC. I think I
>> saw it discussed here a year or two ago, but it's not like turning off the
>> AGC in an analog receiver. The Orion II is truly a DSP radio and some
>> things must be done differently for real-time DSP to work without some
>> pretty hideous artifacts.
>> Kim N5OP
>> On 12/19/2014 4:13 PM, Richards wrote:
>>> Good stuff.     So,  I suppose I am nuts for turning AGC off, and
>>> working the RF-GAIN control?
>>> I understand Rob Sherwood, among others, have problems with local noise
>>> causing issues with AGC on the Omni VII and other radios - a strong local
>>> noise event causes AGC to silence the rig for a moment.  This can be
>>> somewhat annoying, not to mention inconvenient.   So, I simply turn AGC off
>>> and operate without it.
>>> Is AGC really a boon,  or necessary feature,  ...or merely a convenience
>>> saving us from tweaking the knobs during a contact. Some guys don't use DSP
>>> NR... obviously we do not always embrace newer, high tech features.   ;-)
>>>  ;-)
>>> Am I out of step here?
>>> As for actual plots, that would be interesting... I think TT provides a
>>> a brief explanation of the AGC functions in the manual and in documentation
>>> supporting the more recent firmware, but I found it  a bit terse and
>>> technical -  not all ham operators are engineers, so I would appreciate a
>>> less technical gloss thereon.
>>> ========================  K8JHr ================
>>> On 12/19/2014 8:57 AM, Barry N1EU wrote:
>>>> I'd like to see a plot of actual behavior of those AGC slope settings.
>>>>  _______________________________________________
>>> TenTec mailing list
>>> TenTec at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>> --
>> Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP
>> SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
>> /"In theory there is no difference between theory and practice. But, in
>> practice, there is." //-- Attributed to many people; it's so true that it
>> doesn't matter who said it./

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