South Arm NEFR – A Tough Radio Challenge
The South Arm and Icicle Brook stages of the New England Forest Rally (NEFR) present challenging communications issues for radio operators.
What is the Primary Problem?
Look at the topographic map below and pay attention to the steep hill/mountain inside the red circle. The top of it is 1,200 feet higher than the roadway at the start and finish of both stages.
What Can Be Done to Ensure Clear Communications?
You need a tall antenna and lots of power to get a signal from the start to the finish if you intend to conquer the mountain using simplex VHF transmissions. The distance between the start and finish as the crow flies is just under ten miles!
A repeater could be located across Upper Richardson Lake about 2/3rds of the way between the start and finish of the two stages. At this location, it would have a very clear shot of all radio operators along both stages. The tall mountain would not hinder communications whatsoever.
You can also put a repeater in a circling airplane or suspended from a tethered balloon. Both of these options create their own set of very specific problems, not the least of which is cost.
There are other significant issues with repeaters. Here are but a few of the challenges:
Repeaters offer up a sole point of failure. If the repeater fails during the stage no one can communicate. With the current simplex setup, if one operator’s radio or antenna fails, only his position is affected.
Duplexers can be sensitive. They are required in a repeater to make the same-band repeat magic happen. These cans usually don’t like being bumped around traveling on gravel roads that have more potholes than Dunkin has doughnuts.
The provider of the repeater has to set up the repeater, controller, duplexers, etc. as well as the antenna in a short amount of time before the stages run.
The repeater location across Lake Richardson may not be accessible just before the rally. The roads may get washed out and the owner of the road may not repair it in time nor want to invest the money to repair it.
What About an HF Solution?
Yes, you might have great success using high frequency (HF) on 80 meters. All operators would have to have HF equipment and be able to deploy an 80M Near Vertical Incidence Skywave (NVIS) antenna.
The US military relies on NVIS operations in battleground situations. It’s that reliable.
A NVIS antenna can be just a simple thin wire suspended about 5-8 feet in the air. You can drape the antenna over tree branches or bushes. You can also use some simple wood stakes to hold it above the ground.
UPDATE: July 22, 2019 – On Friday, July 19, 2019 I did an 80M NVIS test at the start and finish lines of this stage. I was assisted by Sean Tarbox, N1BOX, and Tim Foy, W1FOY. Sean and Tim, along with Tim’s wife Monica, were just below the start of the South Arm start line. I was a mile beyond the finish line of South Arm.
We established crystal-clear comms using a simple antenna that was about 2 feet off the ground at my end. I was only transmitting with 13 watts out of my Elecraft KX3. Sean and Tim experimented with different power levels up to 50 watts. At 50 watts it was if they were standing next to me. A stunning 5-9 signal report.
Watch these videos to get an idea of how easy it is to do NVIS comms:
If you have ideas, put them in the comments below.