On Monday, September 25, I traveled out to Fire Station 61 in Wasilla to test connectivity and throughput with a Ubiquiti RocketDish/Rocket M3 radio to our Site Summit node. A quick setup with the dish mounted to a tripod on the ground showed very good signal levels; about 20 db SNR. Should have made for excellent throughput. Unfortunately, I had virtually no throughput. It just didn’t make sense. I headed over to the Chevron station near Knik Goose Bay Road and Vine, and found about the same thing; good signal strength but no throughput. I gave up and headed home to scratch my head.
I gave Tom Delker, K1KY, a call in Tennessee. Tom has been our mentor for all matters MESH and is a mover and shaker in the AREDN MESH world. He clued me in real quickly. I had forgotten to consider the “distance” setting on each of the radios. The distance setting effectively controls the latency on the transmit/receive cycle. If the latency is too long (or distance setting set too long), you’ll end up with throughput, but its speed won’t be maximized. If the distance setting is set too short (effectively shortening the latency period), you’ll get virtually no throughput. When I made a check of the radios in question, that’s exactly what I found. The distance parameters were set to about 10 miles on each unit, so neither radio would listen for the other radio long enough after each packet for a reply; they’d effectively re-transmit too soon.
I made the necessary distance parameter changes (about 22 miles between Site Summit and Fire Station 61), and voila, excellent throughput! It’s great when a plan comes together!
Today I did a bit of testing from the west side of Lake Hood to Site Summit and our two Hillside Nodes and found excellent signal strength and throughput as well.
Bottom line is that the RocketDish units linking with our 120 degree High-Gain Sectors really work well together. We now know for sure that we’ve got good path and connectivity availability between Anchorage and Wasilla on the MESH and look forward to our friends in the Valley joining the MESH.
If you’d like to learn more about the AARC MESH network and want to get involved, would like to host a node site, or just want to learn more, contact Kent Petty, KL5T (firstname.lastname@example.org).