ALM2TLE is a program to convert NMEA almanac data to NORAD two line element format. This program would be useful to those who want to determine the GPS satellite orbits.
Selective Availability Error Plots
gpsbatt.zip (12524 bytes) has a plot of battery discharge tests using four types of AA cells with a load representing a Garmin 45 GPS.
How GPS Works: An Introduction (7821 bytes) is an introductory article on GPS written by Craig Haggart (haggart@slac.stanford.edu)
dgpsinfo.txt (4227 bytes) is a short article describing Differential GPS.
grm45ant.gif (231453 bytes) is a .gif image of an X-ray of a Garmin GPS45 antenna, also available as grm45ant.jpg (25006 bytes).
grm38jpeg.zip contains 5 jpeg pictures of the insides of a Garmin GPS38, and a picture of a homebrew holder for a Garmin 38. From Harrie Gulikers (hgu@oce.nl)
ga26.zip contains two .gif pictures of the insides of a Garmin GA26 "patch" antenna, sold as an accessory for the GPS-45.
vista.rev (15,470 bytes) is a review of RMS Technologies "Vista" moving map software. This is an MS-DOS program that will display maps (your own scanned ones, or purchased ones in many formats) and will plot positions based on NMEA-0183 RMC sentences from GPS receivers.
utmgrid.ps is a postscript file to print grids that can be used to plot or read positions on USGS 1:24,000 or 1:25,000 topographic maps using the UTM grid. Just copy this file to a postscript printer. Also available as utmgrid.pdf which can be printed using Adobe Acrobat 3 (available from http://www.adobe.com)
mapgrid3.zip (292K Jan 10/99) makes grid overlays for topo maps on an HP Laserjet II or 4. UTMGRID makes a kilometer grid and can also make graph paper. LLGRID makes a lat-lon grid for USGS 1:24000 maps. With full Fortran and asm source. By R. Thrun
