station back online

[The following is a slightly edited version of an email I sent to Jim Hendee (CHAMP principal investigator) on January 13th, 2011.  It summarizes the results of a visit by Jack Stamates (FACE project) and myself to the station that morning, where our intention was to investigate what might have caused the station to stop transmitting on December 29th, 2010.]

On January 13th, 2011, I wrote:

Jack and I visited the station this morning.  The entire base (?) lost power for a week over new year's, Dec 27th to Jan 3rd.  [This was apparently due to a disastrous FP&L screwup.  Jack knows/understands more of the details of this.]

The station batteries performed beautifully and everything continued to operate normally (ADCP, CT, logger, WXT) except the sat transmitter.  So we lost no data whatsoever.  Jack was thrilled with this test of the station's operation during an extended power loss.  Great design!

The one weak point continues to be the ancient satellite transmitter.  At the battery levels recorded by the logger, even the transmitter should have continued to operate normally.  But something about those slightly-lower voltage levels, or possibly there were repeated voltage drops or spikes, something spooked the transmitter.  It was NOT in failsafe mode (I could see that when I connected directly to the transmitter) but it had stopped communicating with the logger, so it had no data to transmit.  Pushing the failsafe-reset button seems to have brought it back to life.  Remember, this is one of those old SAT-HDR-GOES transmitters, the last one (of five original) that still works at all.

Mike J+

Note that while Jack and I were visiting, we again downloaded all available ADCP data and swapped datalogger memory cards, an operation that normally occurs about once a month.

transmitter failure

[The following post is a copy of an email message I wrote to Jack Stamates on January 5th, 2011.  Transmissions from the Port Everglades station had stopped on December 29th, 2010, and we were planning to visit the site to see what may have gone wrong.]

On January 5th, 2011, I wrote:

I've updated all of my spreadsheets and data files with the most recently retrieved data card, from November 9th.  I've also had a closer look at the data from immediately before the station stopped transmitting, and there's a suggestion that something weird started happening a few days before.

The first hint of trouble was a skipped transmission on Monday, December 27th at 1pm local time.  When transmissions resumed in the next hour, the voltage diagnostics looked different than before.  The logger reports min, max and average voltage numbers -- normally the min numbers hang around 12.8V, the average at 13V, and the max around 13.8V.

Beginning Monday afternoon, the max and average value both dropped to about 12.8V and the min fell below 12.5V.  Things went on like that for about two days until transmissions ceased on Wednesday night (Dec 29th) at about 8pm local.

So this probably isn't the same transmitter-failure problem we've seen in the past.  The sure sign of that problem is that the GPS acquisition times go through the roof in the times leading up to the failure, and there was no sign of that in this case.

It would seem the station has a power issue of some kind.  This could mean that something weird is going on with the external power source; or the datalogger might be suffering some kind of power problem internally; or something connected to the logger might have short-circuited.  [In the past, we've seen something similar when an underwater instrument has a bulkhead failure and floods, shorting power to ground and draining the power supply of all the other instruments.]  There is no sign of trouble with the CT numbers that I can see in those past few days, or the meteorological instruments.

So anyhow, I'd suggest you prepare yourself for a wider range of problems when you go.  If you want me to meet you there, let me know, it's usually no trouble since I live so close.  Also, there's no guarantee that this is a transmitter-only problem, so you may find that the logger hasn't been storing the CT data to its memory card in the last week.

I've formatted your spare memory card so you can swap them out during your next visit.  I'll bring in by your office today.

Mike J+