TM 5-6675-318-14
d. A set of Cartesian coordinates is calculated representing the estimated
MX 1502 position at the beginning and end of each doppler count. The range from the
satellite to the estimated MX 1502 position at each time mark is calculated. The
doppler counts are measures of the actual changes in range between satellite and
MX 1502 over the doppler counting interval.
The measured range differences derived
from the doppler counts are compared with the corresponding calculated range
d i f f e r e n c e s .
e. By computing derivatives with respect to latitude and longitude, the MX 1502
determines how far its estimated position should be moved to minimize the least
squares differences between the measured and the calculated range differences.
These calculations are repeated two or three times until the solution converges .
f. There are two methods for determining a three dimensional point position.
They are point positioning and translocation.
P o i n t p o s i t i o n i n g i s a c c u r a t e to
within 5 meters rms and translocation is accurate to within 1 meter rms.
Both
methods can be utilized in either real time or off-line mode .
g . P o i n t p o s i t i o n i n g i s a c u m u l a t i o n o f s a t e l l i t e d a t a f r o m 1 0 t o 5 0 s a t e l l i t e
passes collected by a single MX 1502.
In the real time mode, 3D point position
information can be retrieved after each acceptable satellite pass.
I n t h e o f f - l i n e
mode, collected satellite data that has been recorded can be post-processed to
derive the 3D point position .
h. Translocation uses data collected from two MX 1502’s located at separate
stations tracking the same satellite simultaneously. Translocation can be used in
either the off-line or the real time mode .
This method determines the relative
position of a remote site with respect to the control site .
4 - 3 . 2 D e t a i l e d .
a.
The antenna/preamplifier is a dual-frequency tuned monopole antenna designed
to receive 150 MHz and 400 MHz radio signals.
The preamplifier provides gain at the
antenna to maintain system sensitivity.
The received frequencies are amplified in
narrow bandwidth receivers to filter out unwanted VHF and UHF frequencies.
The
power for the preamplifier is supplied through the coaxial cable by the receiver/
processor and is -10 V.
During a self-test, the power to the preamplifier is turned
o f f .
b . T h e 6 / 8 b o a r d i s a d u a l - c h a n n e l s a t e l l i t e r e c e i v e r b o a r d . I t h a s a p a s s i ve
diplexer to separate the 400 MHz and 150 MHz signals which are then sent to the
receiver section where the doppler and message data are developed. These signals
are then processed to produce four outputs to be sent to the processor board. The
four outputs are doppler count, data,
signal value, and phase error.
The dual-channel satellite receiver board develops 150 and 400 MHz signals to be
u s e d i n s e l f - t e s t.
The board has two voltages supplied from the power supply +5 V
and -10 V.
The +5 V for use on the board and -10 V for the preamplifier. The -10 V
t h a t i s a p p l i e d t o t h e p r e a m p l i f i e r i s t u r n e d o f f d u r i n g s e l f - t e s t t o p r e v e nt
o u t s i d e i n t e r f e r i n g s i g n a l s .
4-11
