[ldm-users] Those with direct satellite feeds of NOAAport...

[Gilbert Sebenste]

On Wed, 14 May 2008, Mike Schmidt wrote:

Hi Mike,

This is the post I was looking for...

> Gilbert,
>
> For what it's worth, we hardly ever have a day free of Gap messages.
> On the day you cited, May 11th for example, we have six Gaps;
>
> May 11 11:01:58 burns dvbs_multicast[2328] ERROR: Gap in SBN last 5921901, this
> 5921922
> May 11 12:10:48 burns dvbs_multicast[2327] ERROR: Gap in SBN last 19263061,
> this 19263064
> May 11 12:16:58 burns dvbs_multicast[2327] ERROR: Gap in SBN last 19278632,
> this 19278634
> May 11 14:56:20 burns dvbs_multicast[2330] ERROR: Gap in SBN last 5000158, this
> 5000160
> May 11 20:13:33 burns dvbs_multicast[2330] ERROR: Gap in SBN last 5263333, this
> 5263336
> May 11 22:56:57 burns dvbs_multicast[2327] ERROR: Gap in SBN last 21252753,
> this 21252755
>
> We feed directly from a 3.8m heated NWS installed and maintained
> NOAAport dish installed for COMET.  Other than local terrestrial
> interference, a truck driving in front of the dish (it's possible
> with the installation here), or a solar eclipse, the data reception
> should be about is good as it gets.

OK.  I had 40 that day, but we also had 45 MPH winds and heavy rain.
That certainly didn't help. I know that our struts vibrate in high wind 
slightly, and I suspect that might be a problem (we are ordering 
heavy-duty struts to replace the ones we have there now). But
outside of that...

> We have found that the Gap messages we see are usually consistent
> system-wide.  In other words, the majority of the Gaps we see here in
> Boulder are the same ones that SSEC and LSU see.  Check your data for
> May 11th and see if you have the above six Gaps in your logs.

Yes, I do.

> Otherwise, you may have additional issues to find and resolve which
> can include anything from temperature and moisture sensitivities in
> the LNB and cabling, all the way down to overflowing buffers, too
> many interrupts or a bad driver for the ethernet interface.
>
> Here's a week's worth of our recent Gap history;
>
> May 07		25
> May 08		28
> May 09		35
> May 10		9
> May 11		6
> May 12		95
> May 13		23
>
> Hope that helps.
>
> mike

That's better! That's what I am typically seeing, or very close to it. 
With a 12' dish, a Norsat 3120 LNB and a Novra box, I should be smokin',
especially with a variable bit error rate one level better than standard.
I will try one more thing: my Novra box is 5" away from the computer; I'll 
try moving it off the computer stand and see if that helps any. I'm using 
quad-shielded RG-6, but you know how much computers spew RF... :-)
Looks like I'm trying to make a problem where none exists. Thank you for 
the verification.

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Gilbert Sebenste                                                     ********
(My opinions only!)                                                  ******
Staff Meteorologist, Northern Illinois University                      ****
E-mail: sebenste at weather.admin.niu.edu                                  ***
web: http://weather.admin.niu.edu                                      **
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