Mobile Command Unit

Replies to This Discussion

Permalink Reply by opg4759 on October 4, 2010 at 2:20pm

This is one of the projects I'm currently working on specifically with APRS and Damon with the cross band repeater system.

It's mainly setting up at base and having multiple radios and an operator to go along with it.

Cost is all dependent on how much you are willing to spend.

Permalink Reply by potatomutato on October 4, 2010 at 2:27pm

cool, that would be perfect. this kit will be my next "mod" since it is crucial to our events and i'll even get my HAM license at some point to operate it.

i spent a day at base camp during the most recent High Sierra run and it would have been nice to have been in contact with some folks...not that it was necessary, but you never know what could come up in the future. i could've definitely used it at AllCal as well.

it would be ideal to have a relatively portable system that can be set up in about 15-30 minutes. i wouldn't want to skimp out on pricing, but wouldn't want to break the bank either. i would say the cost threshold would be a "good, effective working system."

Permalink Reply by potatomutato on October 4, 2010 at 2:38pm

Josh, i'm assuming with the APRS set up, we could effectively track rigs out in the field. how would the tracking/reporting be done if we're monitoring remotely (e.g. not at home)?

Permalink Reply by opg4759 on October 4, 2010 at 5:24pm

One of my projects is a portable Digipeter for APRS that is powered by solar and batteries that we can place at a high point.

A friend of mine has a portable voice repeater we do is with when we do group trips to Tahoe.

Permalink Reply by potatomutato on October 4, 2010 at 6:18pm

hmm, i may have to make it out to Pacificon to check it out. i'll let you know a couple days in advance if i can make it.

Permalink Reply by potatomutato on October 4, 2010 at 6:29pm

i like how you think.

Permalink Reply by Bz on October 4, 2010 at 7:32pm

Nice!!!

What could I expect to pay for that set up???

Permalink Reply by opg4759 on October 4, 2010 at 7:47pm

to listen in on HAM frequencies you don't need a license. To transmit you will need to get your Tech license.

The above setup is just a scanner 25-50 bucks used since you don't really need a complex scanner just something that receives VHF, a computer and software is freeware.

But it will only allow you to listen.

Permalink Reply by manoweb on October 4, 2010 at 2:31pm

A generator seems a bit much to me. Normally for this type of operation batteries should be just fine. A pole and a good vertical antenna would serve the purpose. For the ham antenna, we can start from 50-70 bucks I guess; anything more than that will be bulky and not easy to operate on the field, especially in a windy environment.

The best way I've found to mount a pole on the field is a "holder" made with a piece of pipe welded perpendicularly to a plate that is put to the ground and then you go on top of it with a tire of a car that keeps it steady.

Some RG213 cable that goes to the unit either inside the car or on a small table close by, maybe an "easy up" if the wind allows, and the control center is on the air.

Permalink Reply by potatomutato on October 4, 2010 at 2:41pm

what type of batteries are we talking about?

good idea regarding the foundation for the antenna and the antenna does not seem that spendy so far. would you happen to know the optimal height the antenna should reach? 2-3m?

Permalink Reply by manoweb on October 4, 2010 at 5:14pm

I've used batteries as small as 7Ah to huge 180Ah. The best setup is probably about the size of a car battery. Ideally, you would recharge it every day or so connecting it to a car. The "deep discharge" batteries cost more for the same nominal charge but last more.

For the foundation I can ask some pictures to be sent to me from my friends so you can have a better idea, but it's really simple to build one, and very effective.

For an antenna position, the higher the better, but a 2-3m telescopic pole is already good. On orographically "interesting" places like most of the ones we visit during our trips, it make sense to have a radiation pattern that is "wide" on the elevation side so it can better use the reflections of the mountains. It is intended to be a "tactical" use antenna for local (tens of miles) communication. For this reason we cannot have a very high gain so the antennas are not extremely long and expensive:
http://www.rfparts.com/diamond/x50a.html
This, for example, is 170cm long and does not need to be assembled (it comes in one piece) so it's very quick to setup at the camp. It costs 99bucks at hamradio.com (it's an original japanese "Diamond") but there are very very similar models for less.