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[McIDAS #WWA-177597]: GOES South Antenna Pointing

Hi Fred,

> This morning I got an e-mail from Ken Sheggeby of Telvent-DTN.  He is
> the software engineer in charge of the McIDAS software and SDI ingestors
> at Telvent in Minneapolis.  I worked with him last year with McIDAS
> processing software.  He was having problems with Unidata SOUTH data in
> that there was an image with a date/time of tonight which was preventing
> the IMGCOPY of today's data.

Ken sent us an email also.  I deleted the entry pointing to the image
with the incorrect time in all dataset descriptors in which it was
found (ALL, NH, SH).


- you say that Ken is in charge of SDI ingestors at Telvent

  Do they not have an SDI for GOES data?  Or, is it that they
  are not ingesting data from GOES-South?

> In looking at the problem, I noted that
> your SOUTH ADDE database appears to be losing the GOES-12 signal around
> 0Z-1Z.

We are not seeing a signal unlock at any time of the day on our GOES-South
ingest system.  We would expect to see an unlock OR very noisy images
if we are on the edge signal-wise.  I just took a look and see that images
close to 0Z do, in fact, have problems:

  62  G-12 IMG      25 APR 12116  01:28:00   -19   62 1-4,6
  47  G-12 IMG      25 APR 12116  01:15:00   -19   62 1-4,6
IMGLIST: Description for SS number -1 was not found in the file SATANNOT
IMGLIST: Description for SS number -1 was not found in the file SATANNOT
IMGLIST: Description for SS number -1 was not found in the file SATANNOT
IMGLIST: Description for SS number -1 was not found in the file SATANNOT
 118  G-12 IMG      25 APR 12116  01:15:00            1-4,6
IMGLIST: Description for SS number -1 was not found in the file SATANNOT
 117  G-12 IMG      25 APR 12116  00:58:00   -19   62 1-4,6
  39  G-12 IMG      25 APR 12116  00:45:00   -19   62 1-4,6

> Since the GOES-12 is out of fuel for orbit maneuvers, the figure
> 8 pattern in the sky of the satellite location is slowly growing larger.
> It appears that the GOES-12 is going outside the field of view of your
> antenna around 0 Z.  Since you are not losing data around 12 Z, it would
> appear that your antenna is not pointing at the center of the figure 8.
> You might want to reposition your antenna around 18Z so that it is
> pointed at the center of the area of reception.  This might improve your
> reception for a few more months.

We'll take a look.

> As the figure 8 grows, it eventually will become larger than the field
> of view of your antenna, and you will need some active tracking system.

We implemented single axis tracking for GOES-South when it was GOES-10.
Since the switch to GOES-12, the dish which had the capability to track
was repurposed to ingestion of GOES-East.  The dish which is being used
for GOES-South ingest should be capable of doing single axis tracking,
and getting it setup is one of the items on our list of things to do.

> Many years ago, during GOES-7, we had this problem with our GOES
> antenna.  There were commercial tracking devices, but they were quite
> expensive.  We (NSSFC) solved the pointing problem by having one of the
> technicians set up a program on an old computer to pulse the antenna
> drive motors every few hours.  We would use the clock to compute how
> much of a pulse was needed and which direction.  I remember coming up
> with an algorithm to compute how the figure 8 would grow with time, but
> GOES-8 was launched so we didn't have to use my growing program.  Does
> the South antenna have electric motor drives which could be used to
> reposition the antenna to follow the satellite?

We have the hardware needed to do tracking.  The one "quickie" attempt
we made at testing things (motor, etc.) revealed some problems that
still need to be addressed.


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Ticket Details
Ticket ID: WWA-177597
Department: Support McIDAS
Priority: Normal
Status: Closed

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