On Sun, Oct 21, 2012 at 7:00 PM, Jay Salsburg jsalsburg@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