If you don't operate or care about GRB ground station operations, please
just hit delete. For those that operate a GRB ground station, here is some
important information from Toby Hutchings with NESDIS on the upcoming
roll-out of GOES 19 into operations:
Greetings User Community,
Broadcasting answers to frequently asked questions to the community. Below
you will find the latest topic of discussion.
*Is there an expectation that some GRB users may need to re-point their
antennas in connection with the G16 "nudge", and then re-point again for
the transition to G19 GRB? If so they might like to know the specific date
of the nudge.*
*"Short answer: Assuming GRB users are operating an antenna 7m or smaller,
they should not have to re-point their antennas during the G16 to G19
transition.*
*Longer answer: GOES 16 is being nudged from 75.2 deg W to 75.5 deg W.*
*Using our HR5 antenna here at WCDAS as a reference, the difference in
ground antenna pointing angles between these two orbit locations is as
follows:*
*HR5 - GOES 16 (75.2 deg) = 179.50 deg AZ and 44.95 deg EL*
*HR5 - GOES 16 (75.5 deg) = 180.06 deg AZ and 44.85 deg EL*
*The difference in ground antenna pointing angles is 0.47 deg AZ and 0.1
deg EL*
*Assuming a GRB user is operating a 7 meter antenna, the half-beam width
calculations of that antenna at 1.686 GHz is as follows:*
*0.25 deg = 0.25 dB*
*0.35 deg = 0.5 dB*
*0.5 deg = 1 dB*
*0.86 deg = 3 dB*
*Since the expected pointing angle offsets are 0.47 deg AZ and 0.1 deg
EL, the expected downlink degradation should be between 0.5 and 1 dB. This
expected degradation should not cause an issue with users assuming that
their antennas are peaked on G16 at its current location. If they are not
peaked currently, this move and resulting degradation could cause issues.*
*Additionally, any users with antennas larger than 7m will have narrower
beam widths and thus experience a greater signal drop from this move. For
example, if our 16.4m HR antennas were not autotracking, we would
experience a 6dB drop in signal from this move if we did not re-peak."*
Special thanks to Matt Sullivan from our WCDAS Team for providing a
detailed response!
-
Stonie Cooper, PhD
Software Engineer III
NSF Unidata
cooper@xxxxxxxx
