A disk and navigation apparatus for reproducing the disk in a position locating system wherein the maps are more clearly displayed without requiring a large increase in the amount of data storage capacity required. On the disk there are recorded in a frequency division multiplex mode a video FM signal...http://www.google.com.mx/patents/US4849827?utm_source=gb-gplus-sharePatent US4849827 - Disk and navigation apparatus for position locating system
