[arm-allstar] Observations: 2000 miles mobile with an 888 node

[John Wagner]

I built up an 888 portable node about 6 months ago, and have used it
previously a few times mobile for shorter trips and stationary on vacation.
I had a chance to give it a workout mobile over Labor Day weekend on a 2000
mile drive from Phoenix, AZ to Akron, OH. I figured I'd share my setup and
my results.

First, a big thanks to everyone that figured out the ins and outs of
putting one of these together. It's a slick setup.

My setup is:
- Baoeng 888
- two cheap DC-DC converter boards from Amazon - one for the Pi @5V, and
one for the 888 @3.7V
- modified USB soundcard
- RasPi 3
- RasPi3 using WiFi joined to an iPhone 6S+ on Verizon with Personal
Hotspot turned on
- Accessed the node with a Yaesu HT.
- I experimented both with and without OpenVPN to tunnel traffic out to a
free tier Amazon EC2 instance
- I experimented powering the whole thing off a 12v 5Ah gel cell, and off
the car's power socket

I had the mobile node connected back to a couple of our local RasPi Allstar
node/repeaters in the Akron area for about 18 hours out of the 29 hour
drive, and in active QSO for probably 8 hours out of that. The entire trip
was over Interstates (I17, I44, I40, I70, I71) that had pretty good
cellular data coverage. The bottom line - it worked great! It was a great
tool for me, and also educated and impressed a lot of people in our area
about the strengths of Allstar.  When I got back into the home area, I
switched my HT from using my mobile node to going directly into the local
repeater, and aside form the different courtesy tone no one could tell the
difference in audio.

Here's a few specific observations:

   - I can't explain this, but while driving through parts of Arizona, New
   Mexico and Texas I was unable to connect outbound from the node back to the
   home nodes without using OpenVPN to carry the traffic. I was on LTE for all
   of those attempts with 3 bars or higher signal on the phone. Once I made it
   to Oklahoma and beyond, I was able to connect outbound without OpenVPN. I
   can't imagine that Verizon has the network configured differently in
   different areas of the country, but I suppose it's possible. I'd stop,
   enable OpenVPN, reboot, and it would work outbound just fine from
   everywhere I tried it. The other nice thing is the OpenVPN allows inbound
   connections as well, although I didn't use that on this trip.
   - The 5Ah gel cell powered the node for 12 continuous hours without a
   problem, and I came to prefer it over using the car's electrical system. It
   was down to 12.1V by the end of the 12 hours, and I recharged it with a
   wall wart overnight. 1) the node stayed up when I stopped at rest areas and
   gas stations and turned the car off and 2) I had a couple unexplained
   reboots of the RasPi while driving and connected to the car's power outlet.
   That could have been a connection problem or perhaps a spike that made it
   through the DC-DC converter.
   - While moving down the highway, audio reliability was very good in both
   directions. About once every 10 minutes in QSO, I'd hear a digital burst in
   the audio of about 500ms, perhaps during a cell site handoff or a dip in
   cell signal. People on the other end of the QSO reported the same behavior
   on their side. It didn't really impact the QSO, it was just observed.
   - It's hard to tell exactly how much data I used on the cell connection
   since it's mixed in with the other stuff going on on the phone. However...
   on my active QSO days, I used less than 300Mbytes on my data plan for my
   phone. I suspect most of that was NOT Allstar, but don't have logs to prove
   it.
   - My final favorite, most reliable configuration for mobile use was:
   - Gel cell powered
      - OpenVPN from the Pi over the hotspot connection to the EC2 instance
      - Use the *73 "permanent" connection to the node you connect to. Then
      if you do get a dip in coverage, OpenVPN will auto-reconnect, and Allstar
      will then auto-reconnect with no user interaction required.


  - John, N8CD
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