On 1/4/17 10:37 PM, Luis V. Romero wrote:
Are you guys doing the link between the two HamWAN sites via RF? If so, what is the link budget?
The radios are at -63 now at 140 Mbit/s. We need -70 or better. I think we need to tweak it a bit more, it can improve.
Since you tested it in the winter, I suspect lots ofFresnelzone issues and reflection off of the bay plus tropo issues in the summer.
Yes, but we can maintain a link to -90 and the radios will modulate down (with a drop in throughput)
How do I know this? I had a2 watt/30dBi gainHorizontal pol7GHz hop from across the street from RayJay to Riverview over Hillsborough Bay and in the summer, the path was a mess due to temperature inversion layer differences over ground vs the bay… Needed diversity receive antennas at Riverview. I had a hell of a time with that path! Thank god for Fiber – The RF path was the secondary STL for WFTS.
Who decided to do horizontal pol over the water? We run MiMo with H&V polarity. there is a much better dispersion fade margin in modern digital radios. The older analog radios needed a very hot signal to make it work due to the limited recovery due to fades built in.
The path over the bay is BRUTAL in the summer, especially in the early morning/late evening.
Wonder how this will affect that link. It will be interesting to see. Don’tknow how much fade margin you guys have in the link budget.
I need to start graphing it. It's going to be fun, and it's ham radio :D -- Bryan Fields, W9CR Florida Simulcast Group, Inc.