ATP-3-09-02 Field Artillery Survey Download
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Global Positioning System Application and Systems 16 February 2016 ATP 3-09.02 9-5 datum, and indicate a FOM 1 before the coordinates will be used. The PLGR with a FOM 1 will meet or exceed an accuracy of 10 meters CEP for horizontal and 10 meters PE for vertical. The averaging mode will yield a more stable and accurate set of coordinates. After the set attains FOM 1, switch to the averaging mode, and allow the counter to increment to at least 300 counts. (This will take about 5 minutes.) Position data should always be checked by a second independent mean; for example, a second receiver, an accurate map spot, or the current coordinates on the IPADS or IPADS-G. Height. The PLGR can determine height (elevation) relative to either the horizontal datum ellipsoid (spheroid) or mean sea level. Both modes of operation can be set for meters or feet as a unit of measurement. Normally, mean sea level and meters will be the preferred selections. Direction. The PLGR cannot be used to determine orientation azimuth for firing positions. As with the IPADS or IPADS-G, azimuth computed between two sets of GPS coordinates will produce erratic results. IPADS or IPADS-G operation. The PLGR does not require any special installation for IPADS or IPADS-G operation. Position coordinates for initialization or update can be obtained by moving a short distance away from the vehicle and placing the set directly over the desired location. Using the system away from the vehicle will reduce the possibility of antenna masking. When the averaged FOM 1 coordinates have been recorded, move the IPADS or IPADS-G vehicle to the PLGR position. If the PLGR auxiliary antenna is mounted on the vehicle when using IPADS or IPADS-G, the precise GPS vehicle lever arms information (X, Y, and Z) must be entered during system initialization. When using the PLGR during IPADS or IPADS-G operations, only data determined from a FOM 1 will be used. LIMITATIONS AND CONSIDERATIONS MASKING 9-10. GPS receivers rely on electronic line of sight with the satellites. Therefore, dense foliage, buildings, mountains, and canyons may mask the signal. The PLGR will initially select satellites that are 10 degrees or more above the true horizon. If usable satellites are not detected, the set will switch to 0 degree until satellite acquisition. After acquisition, the set will switch to 5 degrees above the horizon for normal operation. If enough satellites cannot be acquired, the receiver must be moved to a more suitable location. JAMMING 9-11. The AN/PSN-11 is subject to jamming. When low signal to noise ratios are detected or reception is blocked altogether, jamming may be the cause. Move to a new location, and try to place something between the receiver and the suspected jammer. When the signal to noise ratio is above 34 decibels (db), jamming has probably been eliminated. SPOOFING 9-12. The PLGR may be subject to spoofing errors. These errors are caused by false satellite signals designed to generate errors in navigation and position data. Maximum protection against spoofing is attained by using the crypto keys and the All-Y setup selection. If the PLGR is in a spoofing environment, the system may sense spoofer activity and generate a POSSIBLE SPOOFERS warning screen. TEMPERATURE 9-13. The PLGR operating range is -4°F to +158°F. When operating in cold regions, protect the receiver by carrying it inside your outer clothing or operating it from a heated vehicle and using the auxiliary antenna.