Getting Internet access and N3FJP Logging configured at your ARRL Field Day site

ARRL Field day is an exercise for emergency communications, and a fun contest for ham radio operators.

Most clubs use software, like N3FJP to handle logging from multiple locations at the same time. This presents the need for a network to connect the server to the clients.

Having done this many times in many different field day sites, I humbly offer my advice.

  • Keep it simple. Single wireless network access point may be all you need (have a spare just in case)
  • Mesh networks are neat, but they are added complexity if you don’t need them (you often won’t need more than an access point if you can get it high enough.) Consider only using the mesh for the internet path, and keep it outside of the logging-device path if you can.
  • Wireless devices are relatively noise free. Wired ethernet, less so. When possible, have some shielded ethernet cables handy in case you get HF noise from your cable runs.
  • Use TCP mode in the N3FJP software – it’s way better than the old way… Also, run a script to back up the database on the back-end.
  • Test before Field Day!

Now, that’s all good and now we’re hooked up and logging. But most people are also used to having internet – it’s good for conferencing in people who aren’t at the site, spotting where your digital signal is going, downloading that latest WSJTX or CW decoding software you’ve been meaning to upgrade, keeping your employer at arms length and keeping YOU from having to leave Field Day and have to drive in…

Most years, we’ve at least provided basic internet to our Field Day network. The easiest way to host a network would be to go 100% wireless – just get a wifi hotspot, go into its settings, and crank up the number of allowed connections, rename it and set a password for the event, then connect in with wireless on your server laptop and use only wireless. This works but has some limitations – some devices max out at 16 connections (which is a bit anemic). Built in hotspot antennas are NOT ideal, and they’re generally not meant to have so many users at a time. (however, some hotspots are small enough to put in a watertight enclosure on a 30″ pole, and even though USB spec doesn’t allow a wire that long, getting some voltage to it only on the power pins will probably work for a very long time)

Sometimes you may want an actual hardwired ethernet port, or more users.

This is the configuration that I’ve found to be the most robust for Hotspot to Ethernet, on the road:

Our internet access comes from an old-school Verizon hotspot. That goes to a GL-Inet router (the thing in yellow). This thing is inexpensive, runs Linux and can do just about anything. Well worth the $30. For testing at home once, we swung our whole home internet off of cable, and on to this device, using cellular plan internet. It all worked. None of the devices in the house noticed they were not on Comcast anymore. In this case, it provides power to our hotspot on the USB, and connects the wireless network to an ethernet port. It does that running off of USB, which provides power backup running off of the laptop battery (very important for generator-powered FD operations).

You COULD use a GL-inet device for everything, but we like to have our logging server behind a NAT (network address translation) so that internet access is outgoing only and can’t affect the server. Also, if you want to do more on GL-Inet there are other models with dual-band and better antennas that I’d chose to use instead (maybe next year?). There is a captive portal feature that could even direct visitors to your website.

The GL-Inet can feed the internet in either by tethering, direct ethernet connection, or by a wifi connection to somewhere else (building, standalone hotspot, phone/tablet hotspot, etc). It provides two ethernet jacks – one for WAN and one for LAN (but both can be LAN if that’s what you need).

The wifi router is old, but don’t knock it. It runs on 12V DC, and it’s been proven not to provide any HF noise. Your mileage may vary. We normally run the access point off of RV batteries rather than a wall-wart.

The end result is something that can get to the internet, that works, that can tolerate temporary power loss without losing network connectivity, and holds up the logging network.

Speed is best with devices on the 5 gig wifi band. My hotspot access points are set to 2 gig because of some legacy uses, but we’re still getting 20 down 8 up. Plenty for average field day needs.

Hope you all have a safe and fun Field Day 2021.

If you have something else that works well, or comments, please let us know!

-Tim

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