[aprssig] Mobile Off-Air Display

Andrew P. andrewemt at hotmail.com
Wed Aug 12 11:04:29 EDT 2015

Actually, this is a very good idea for more than one reason. For one particular bicycle event my ARES group works around here, the vehicles that are loaned for SAG are the first ones I've seen where the cigarette lighter sockets turn off when the ignition goes off. Good for not destroying your car battery when you leave stuff plugged in, but horrible for keeping a tracker going while you are stopped at one of the rest stops loading/unloading the vehicle with supplies and/or exhausted riders. Net Control kept calling us on on cell phones wondering why we kept dropping off the map until we figured out what was going on.

Date: Tue, 11 Aug 2015 21:52:11 -0700
To: na5dw at cox.net
CC: aprssig at tapr.org
Subject: Re: [aprssig] Mobile Off-Air Display
From: aprssig at tapr.org

The attached photo is a simple schematic. Basically, we connect to car power through a one ohm resistor. It basically makes high current draws come from the battery instead of the car, but allowing the car power to keep the battery topped.
We run about 15-20W TX power. We have not had power issues for all-day events, plus the battery allows the op to continue working if he needs to temporarily disconnect from the car (or if the car turns off the power socket when they are one break.
If you have any questions, please feel free to msg me direct at na6br at blandranch.net. Happy to help.
On Tue, Aug 11, 2015 at 9:28 PM, Dan Walls <na5dw at cox.net> wrote:
Can you give me some more info about how you provide power for your sag radio's.  I am helping the the tour de cure in Colorado this weekend and I will be using car provided for me.  The power issue is a concern to me.  I thought about powering the mobile from a 7 amp h  battery.  I am concerned about how long the battery will last.


On Sun, Aug 9, 2015 at 6:25 PM, Charles Bland via aprssig <aprssig at tapr.org> wrote:
I'd like to get the latest opinion from this group about putting together a simple mobile APRS display solution.
Our local club does a couple of bike events each year. We have an ad-hoc network to support our trackers over the course area. I have been turning my attention toward broader use of the info. For example, our rest stops now have displays, and we run a Public Info table so that we can make event participants aware of what we do and how we do it.
I am now turning my attention to our radio operators in the sag wagons. For insurance purposes, the bike club provides the cars and drivers. The radio op rides shotgun, using a Go-Box that has battery assist so that the cigarette lighter adapter isn't doing the heavy TX lifting and can be shared for other uses.
I'd like to have simple, non-transmitting display setup so that the operator can "look" around the course as he has need. I'm not sure where to start looking for commercial solutions, if there are any at all. I also have been wondering, given the abundance of R-PI hardware, if a R-PI and display would be enough to run something like YACC. A simple RX and antenna would be enough, and the package could be small enough to occupy little of the precious space in the vehicle and not pose a safety issue. Even nicer if it could be on the dash.
So, what do you folks know? How would you approach such a requirement?


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Dan WallsNA5DW
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