Hi Gerald,
From my own experiments, I'm not convinced that it's a problem with the
ALC algorithm itself (i.e. that it isn't "ALC overshoot"), but rather
with the placement of the ALC algorithm within the code.
With "stock" code, my measurements show that severe TX overshooting can
occur, and it seems to depend upon the type of waveform used for
testing. Of course, it's always possible that I made a mistake in my
measurements, so if anyone would like to replicate my tests, please do!
The testing procedure is simple and straightforward, and I describe it
in my blog posting at http://k6jca.blogspot.com/ . All one needs is a
scope and some way to monitor one's RF signal with it. (One item I
forgot to mention in my blog post was TX bandwidth. I no longer recall
what it was for my testing, but 3.8KHz is probably in the ballpark . If
anyone is going to try to repeat my tests, it might be worthwhile to
experiment with TX bandwidth (both low-cutoff as well as high-cutoff) to
see if/how bandwidth affects TX overshoot).
Best regards,
- Jeff, k6jca
Gerald Youngblood wrote:
Steve et. al.
Well, I am going learn not to propose a public hypothesis based on reading
an email. ;>) After testing in the lab, there is no glitch whatsoever when
switching Tune on and off. I set the spectrum analyzer to 0 Hz span, which
makes it able to catch the power of real time glitches. There were none at
all. It was perfect.
Please disregard my earlier speculation as to the faster TR times causing a
problem with spikes on the transmitter. I was simply wrong.
However, we will definitely look further into the ALC overshoot reports. I
did some initial measurements but they are inconclusive so far.
Regards,
Gerald
Gerald Youngblood, K5SDR
President and CEO
FlexRadio Systems(TM)
13091 Pond Springs Road, #250
Austin, TX 78729
Phone: 512-535-4713 Ext. 202
Email: ger...@flexradio.com
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