Easy set-up, vehicle mounted, in-motion tracking, satellite antenna
A low profile, vehicle mounted, in-motion tracking, satellite antenna includes a pair of antenna assemblies mounted in parallel on a rotatable platform. Each antenna assembly includes two subreflectors with a plastic matching element. The outputs of the two antenna assemblies are coupled with a single phase shifter. The combined outputs are retransmitted to a receiver inside the vehicle. The satellite antenna also includes a receiver for receiving channel selection data and/or for providing two-way communication with equipment inside the vehicle. The antennae, transmitter and receiver are self-powered by a storage device which is charged by a wind driven generator. A retractable radome lowers to a lower profile when the antenna is not in use.
1. A tracking system for a vehicle mounted satellite antenna, said tracking system comprising:
a) a yaw sensor;
b) a pitch sensor;
c) a roll sensor; and
d) bias correction means coupled to said yaw sensor, said pitch sensor, and said roll sensor, said bias correction means including one of
first bias correction means for correcting yaw sensor bias where roll sensor bias has been calibrated to zero, and
second bias correction means for correcting yaw sensor bias where pitch sensor bias has been calibrated to zero.
2. A tracking system according to claim 1 , wherein:
said first bias correction means includes means for calculating {DAz+DEl tan(Az)tan(El)} where DAz and DEl are antenna correction rates, Az is the azimuth of the antenna, and El is the elevation of the antenna.
3. A tracking system according to claim 2 , wherein:
said bias correction means includes pitch sensor bias correction means for calculating pitch sensor bias.
4. A tracking system according to claim 3 , wherein:
said pitch sensor bias correction means includes means for calculating {DEl sec(Az)}.
5. A tracking system according to claim 1 , wherein:
said second bias correction means includes means for calculating {DAz+DEl cot(Az)tan(El)} where DAz and DEl are antenna correction rates, Az is the azimuth of the antenna, and El is the elevation of the antenna.
6. A tracking system according to claim 5 , wherein:
said bias correction means includes pitch sensor bias correction means for calculating pitch sensor bias.
7. A tracking system according to claim 6 , wherein:
said pitch sensor bias correction means includes means for calculating {DEl csc(Az)}.
8. A tracking system according to claim 1 , further comprising:
e) azimuth angle correction means coupled to said yaw sensor, said pitch sensor, and said roll sensor for computing a corrected azimuth angle for said antenna based on input from said sensors.
9. A tracking system according to claim 8 , wherein:
said azimuth angle correction means includes means for calculating {Az−(fx cos(Az)tan(El)+fy sin(Az)tan(El)+fz)Dt} where Az is the azimuth of the antenna, El is the elevation of the antenna, fx, fy, fz are derived from the roll, pitch, yaw sensor outputs respectively, and Dt is a time interval.
10. A tracking system according to claim 9 , wherein:
fx, fy, fz are the respective roll, pitch, yaw sensor outputs less the estimated bias for each sensor output.
11. A tracking system according to claim 8 , further comprising:
f) elevation angle correction means coupled to said yaw sensor, said pitch sensor, and said roll sensor for computing a corrected elevation angle for said antenna based on input from said sensors.
12. A tracking system according to claim 11 , wherein:
said elevation angle correction means includes means for calculating {El−(−fx sin(Az)+fy cos(Az)) Dt}.
13. A tracking system according to claim 12 , wherein:
fx, fy, fz are the respective roll, pitch, yaw sensor outputs less the estimated bias for each sensor output.