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I was one end of a mobile link experiment on a long strech of I-10 in west Texas. For sevral hours we passed live video and files back and forth between two vehicles. Antennas were basic factory antennas. A great deal if distance can be gained with better antennas. We were traveling at about 80 mph which is the speed limit in west Texas on the Interstate. Side by side we got very good links. We forced link breaks by alowing one vehicle to get a mile or more ahead of the other vehicle. Then we noted behaviour as we went over hills and made turns that forced the link to break. Once links reconnected in a few seconds with the automatic link OLSR code, the frozen video started to move again with no user intervention. FT file transfers of a 10mb file took from about 30 seconds, to several minutes as all the timeouts and retries in TCP did their retries. With factory antennas on the dash board of the cars involved a range of 2 miles or more was possible in some cases. With better antennas I am sure the range could be improved. In a seperate test a mobile node could pass data to a fixed node in a plastic box, on the ground for about 30 seconds link time. Again, with fore and aft aimed antennas I am sure longer links could be made. We suggest placing fixed nodes on hospitals that are regularly on highly traveled routes. In Austin many are right next to an Interstate or other large highway. Significant sized messages can be passed with link times of a minute or more. Note in many cases aproching the node is all set up time for the link. Most of the data is passed after the car has passed the node. With a good link the entire ARRL handbook in PDF format can be passed in about 45 seconds, so when I say significant sized messages could be passed, I mean LOT of data if you are ready to blast the data over the link when it opens.
KD5MFW
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