[time-nuts] Temperature weirdness with Thunderbolt & Lady Heather 5

Tom Van Baak tvb at LeapSecond.com
Thu Dec 15 07:53:19 EST 2016

Pete kindly sent me the raw data. Well, it's not quite "raw" in the TBolt binary TSIP sense, but a Heather-processed ascii log format. There's something very odd going on here, either with Pete's TBolt, and/or with Mark's Heather v5. I'm happy Pete has a keen eye and spotted this.

1) Attached are two plots of field 6 of the dump file, which is temperature. It shows some classic DS1620 temperature sensor glitches during the first day. This has been discussed at length in years past. The clue are readings that look like xx.75 + ~1/140 degrees. Not a problem in itself.

2) It also shows some truly erratic behavior the last day and a half, with multiple, massive, sudden temperature drops going down several degrees. I've never seen this. It's hard to know for sure, because LH is not storing the actual TBolt raw data in the log file.

3) I would have expected the lines in the log file to be paced exactly once a second. Instead there are some 50,000 cases where the gap is 0 or 2 seconds instead of 1. This is likely a LH problem and not a TBolt/TSIP problem.

4) In addition, there are many, and much larger, data gaps in the log file. The first is a 2 minute gap in data from 16:21:34 1165681294 to 16:23:33 1165681413. In fact there are over a hundred of these larger gaps, as large as 314, 414, and 525 seconds. This is very odd and I've not seen this before with TBolt or LH.

So Pete, Mark and I will talk. Something is very wrong here. We'll take this off-list and report back with the results.


----- Original Message ----- 
From: "Pete Stephenson" <pete at heypete.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Wednesday, December 14, 2016 6:05 PM
Subject: [time-nuts] Temperature weirdness with Thunderbolt & Lady Heather 5

> Hi all,
> I have a Thunderbolt and am running Lady Heather 5. I've been seeing
> odd drops of ~0.7 degrees Celsius that slowly recover over around 10
> minutes or so. This has happened 19 times in the last 36 hours.
> Here's an image of what's happening:
> http://imgur.com/a/LAvmU
> The temperature in the room is not precisely controlled, but is
> reasonably stable over a period of a few hours. There was no external
> events (e.g. opening a window, a fan being turned on, etc.) that
> correspond to those temperature drops.
> Any idea what might be causing this?
> Cheers!
> -Pete
> -- 
> Pete Stephenson
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