[time-nuts] Thermal effects on cables --> ADEV
Tom Van Baak
tvb at LeapSecond.com
Fri Jan 13 14:45:46 EST 2017
Yes, averaging can both enhance precision but also destroy information. In many cases too much data is a bad thing. The solution is to add another dimension to the plot. Stable32 does this with DAVAR (dynamic Allan variance). TimeLab has a multi- "trace" feature. Both of these break large data sets into smaller ones and display each in succession. This way you get the best of both worlds; precision without long-term pollution and also a view of long-term trends. Yes, there's an art to picking the right parameters, but you get the idea. In some cases it is highly informative. The color 3D DAVAR plots in particular can be a thing of beauty.
So, in your case, save each of those 24 hour GIF's and then turn then into a single animated GIF. That way not only do you get a fresh view of current reception conditions, but also a time lapse view of changes over the long-term.
Another idea is to somehow 2D transform your polar plots into a horizontal rectangular strip and then use elapsed time in the vertical. This would allow a waterfall-style representation of GPS reception over time.
----- Original Message -----
From: "Mark Sims" <holrum at hotmail.com>
To: <time-nuts at febo.com>
Sent: Friday, January 13, 2017 11:03 AM
Subject: [time-nuts] Thermal effects on cables --> ADEV
>I recently made a change in Lady Heather's satellite signal maps to help with a very similar issue. Before, the maps were based upon the accumulated average value of the sat signals at each point in the sky. Now, every 24 hours, the signal level averages are reset to their current average and the sample counts are reset to 1. That way any change is your antenna performance won't be masked by days/week/months of previous data.
>> Don't use years worth of data.
> Otherwise it could be days before the xDEV visually changes
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