TriPoint VertexRSI 7200, Руководство по эксплуатации и обслуживанию

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T HEORY
3 - 4
F i gure 3-1 Orb i t Scan Theory
3.2.2 O r b i t S ca n Op e r a t i on
To use O r b i t s ca n i t i s necessary to have correct s i te i nformat i on l oaded i n the s i te
parameters. W hen an O P T target i s bu il t, the user must prov i de the nom i na l
l ong i tude (degrees east) and an est i mated i nc li nat i on. Then the O r b i t s ca n
parameter must be enab l ed. (Note: The l ong i tude range i s N O T used by O r b i t s ca n
but i s used to set up Box li m i ts for the target’s operat i on.)
W hen the target i s se l ected for track i ng, i f no so l ut i ons are ava il ab l e, the system
w ill fo ll o w th i s sequence. If Box li m i ts are enab l ed, then O P T w ill check to see i f
the system i s current l y i ns i de the box. If not, the system w ill go to box center.
Then i t w ill check for a s i gna l . If no s i gna l i s rece i ved, and O r b i t s ca n i s enab l ed,
O P T w ill ca l cu l ate a sate lli te tra j ectory w h i ch p l aces the ascend i ng node at the
nom i na l l ong i tude and prov i des an i nc li nat i on equa l to the est i mated i nc li nat i on
prov i ded.
The tra j ectory i s assumed to be a c i rcu l ar orb i t w i th a s i derea l per i od. Th i s
tra j ectory i s then fo ll o w ed i n steps equa l to a 5 dB s i gna l change based on the 3 dB
beam w i dth of the antenna. The s i gna l l eve l i s mon i tored throughout the operat i on.
If the l eve l r i ses 0.5 dB above the L ow s i gn a l l e v e l set for the target, the sate lli te i s
assumed to be acqu i red. If no sate lli te acqu i s i t i on occurs after one pass, the system
w ill stop at box center and i ssue an O P T ca nnot t r ack a l arm.
It shou l d be noted that the O r b i t s ca n i s on l y used w hen no O P T so l ut i ons ex i st for
a g i ven target. Once a so l ut i on ex i sts, the scan w ill N O T be used, no matter ho w
o l d the so l ut i on may be or i f there i s no s i gna l at the so l ut i on’s pos i t i on.
A t acqu i s i t i on, the system enters steptrack to peak the antenna and then beg i ns
standard O P T operat i on.