Quickly reads in high-data rate data from *.sn1, *.sn2, *.mp1, *.mp2, *.iod and *.ion (UNAVCO COMPACT) files produced from dual-frequency gps data. The data is graphically represented with imagesc. The functionality is similar to TEQCPLOT. However, no graphical functions rely on toolboxes the user may or may not have. MATLAB 6.1 was used--have not tried with MATLAB 7 versions. Also, the color map is default=jet for plotting, which may not be the best colormap for all files.