22 Oct
2012
22 Oct
'12
4:13 a.m.
On Sun, Oct 21, 2012 at 7:00 PM, Jay Salsburg <jsalsburg(a)bellsouth.net> wrote:
Hello Michel
OK, I see you are way ahead of me. However, I have some experience using
these TV Dongles, they have pitfalls. Number one is its frequency Accuracy,
out-of-the-box; needs calibration. Another is that its frequency accuracy
drifts over time and from the Ambient temperature necessitating periodic
offset calibration. While it is possible to create a compensation cure for
frequency drift vs. temperature, it may be far more prudent to place the
Dongle in a temperature controlled enclosure (50C Heater) keeping it above
the ambient to help prevent drift, in your case, the all too important
Temperature related Phase Shift. I have thought of disconnecting the
Dongle's Crystal and placing it in a Crystal Oven, but I have not tried
that. The Entire Dongle is small enough to place it in a temperature
controlled enclosure which also keeps it dry.
Interesting! I was actually considering going the other way, and
putting the radio in a Peltier cooled enclosure, but that was based
only on my experience with cooling digital cameras for
astrophotography purposes to lower noise. I just instinctively
figured that lower temperatures would equate to lower noise in a radio
receiver as well, but I have no experience with the kind of accuracy
drift or phase shift you're talking about. Well, this is definitely
something I will keep in mind when I try to capture my first baseline.
:)
-Michel