Ham radio repeaters: maps / coverage / usefulness?

[e9999]

well, since some of you have been so convincing as to how smart a move it would be to use ham radios in the trucks, I spent some time this weekend at the local ham club, checking out the big Contest. Interesting. Of course, there is a 100 ft or so tower to play with...


one sorta disappointing piece of information I learned (is it right?) is that -contrary to my expectations- a repeater will generally only help you within its radius. So basically, you are at the mercy of whether there is one around or not. I had assumed that once you connect with a repater there is a chain reaction so to speak with others and your range becomes much greater... Apparently, according to the guy I talked to it is possible but not obvious to have the repeaters do that. (of course, things would get very crowded on the bands if that were to happen automatically everywhere).

Soo, that made me wonder. If I'm in the middle of the Sonoran or Mojave desert or in some mountains away from civilization, how useful is that 2m (widely suggested here) going to be if I break down, for me to get ahold of CDan if a mobile 2m can only do 30 miles or so (I think). I imagine there aren't many repeaters in the middle of nowhere.

I tried to find a map on the web that would show the coverage of repeaters and see if that is an issue but no luck. Is there such a thing?

No doubt that a 2 m would be much better than a CB and just the ticket for truck to truck commo, but is it really the ticket for emergency desert type of situations? Or should one try and look at different bands (HF etc)?

Or what am I missing?


added: of course, if the repater is much more powerful than your transmitter, you would greatly increase the area where folks can hear you, but not necessarily where they can talk to you back...

[e9999]

so -practically speaking- are you saying that if I have a 50W mobile 2m I can contact a repeater anywhere in the Mojave?

[Kofoed]

Originally Posted by e9999

so -practically speaking- are you saying that if I have a 50W mobile 2m I can contact a repeater anywhere in the Mojave?

Not the same machine, but at least one macine I would say (canyons excluded). The east Mojave (east of Afton Canyon) gets less repeater coverage than the western portion.

[Cruiserdrew]

Originally Posted by e9999

so -practically speaking- are you saying that if I have a 50W mobile 2m I can contact a repeater anywhere in the Mojave?

Maybe and maybe not. You have to know the repeater is there, it has to be operating, you have to know the access code, and someone has to be listening to it. There is a book called "the repeater map book" that has repeaters listed on a map, from which you could deduce coverage to some extent. The funny thing is, deserts are ideal repeater territory, especially if you can get a bit of elevation.

You can set your radio to scan, and IF someone is broadcasting on a repeater, your radio may be able to read the signal, decode the access code (mine can), then you can set the access code and access the repeater. Knowing the repeaters in the area and trying them one by one is easier, believe it or not. We did this driving through Southern Utah last May, and talked to a bunch of local radio guys who were happy to talk to us.

ARRL publishes "the repeater directory", and while it is reasonably complete, and mostly up to date, it is difficult to use, unless your own knowledge of geography is very complete. The listings are by state and then by county.

I was in the middle of Mojave last month and had good reception of the 2m weather beacons, but did not try the repeater system since I didn't need to. I do carry my directory with me.

If you want to get coverage anywhere, you will need a very sophisticated radio with HF and wavelength capabilities above 10 meters. Oh yeah, and a "General" license.

If you are that concerned, have you considered a satellite phone?

[e9999]

is it easy to get the repeater to broadcast to other repeaters if nobody in the first one's area hears your call?

[MrMoMo]

Some repeaters are set up to do what is called an "autopatch" where you can access a phone line through the repeater, and basically make a phone call from your radio. I believe usually this is either restricted to club members or there may be a charge for it, however in an emergency it may just do the trick.

The other feature of some repeaters is called Echo-link (IRLP). This allows you to call up a repeater - which can then go over the internet to any other echo-link repeater and broadcast your call from the remote repeater. As an example, I frequently hear a repeater in Austraillia echo-link to the one that is local to me, in Kingston, Ontario -Canada.

I would hazard a guess that in most areas... if there is a repeater - someone will hear you.

I am very new to this, so there may well be areas here where I am wrong, If this is the case someone will correct me I hope!

[Cruiserdrew]

Originally Posted by e9999

is it easy to get the repeater to broadcast to other repeaters if nobody in the first one's area hears your call?

No-not unless it is part of a linked system. Some do have the ability to autopatch a phone call, but I've never done that, nor do I know how it works.

If you are going out alone, you would either want to be a very sophisticated operator like ParadiseCruiser or FJ40_Owner, or have a satellite phone.

I should have spent some time in Mojave seeing if the local repeaters provided good coverage, but most of the group was on CB and I wasn't using the 2m that much except to get the weather reports. We should make that a priority on our adventures as it would make the future trips into the same area more secure. Hmmm....Maybe our own "Offroader's guide to amateur radio"

I did start to do that in Death Valley, and will make it a priority this year.

Ron, thoughts?

[MrMoMo]

Originally Posted by e9999

if a mobile 2m can only do 30 miles or so (I think).

I would think that with a good antenna setup and a decently powered radio you should be able to get quite a bit more than 30miles - Obviously dependant on terrain though.

I can get 25km very clear on my radio on low power (10W). I have not yet used my high power setting of 40W. My next radio is going to have an output of 75W.

I can easily hear the repeater across the lake from me 65nMi away, but I am not sure if I can reach it with my radio.

[Cruiserdrew]

e9999-We have talked about distance before. 30 miles is nothing. With clear line of sight to a hilltop repeater, 100+ miles on medium power is pretty standard. See some of the previous Ham threads here in the outfitting section. We have talked truck to truck over 100 miles. I can hit the Walnut Creek repeater (90 miles) from my driveway on 10 watts (Low 2).

[Cabrito]

Yes Yes!
Cruiserdrew I also can hit the W6CX Repeater in Concord (Mt. Diablo) from anywhere in SF Bay area all the way up to our hideaway on Cobb Mt. in Lake County (elev. 2900ft.)
This is with a few 3 and 4000ft elevation ranges in between. Last week I made contact with someone in Elk Grove from Cobb – That is me going about 90 miles to the repeater in Concord and him going about 90 miles to the repeater. It’s awesome! I could never do such a thing with my CB. Even in Simplex mode depending on the terrain I have been able to get 20 miles est. of range on flat ground but it was getting pretty scratchy at that distance.

Ham is the way to go and the test isn’t all that bad.
Icom ic-V8000 is my rig.

Cruiserdrew - Does your radio tell you the off set and the pl? I need to check my manual for this feature -
73-
Michael

[CDN_Cruiser]

A few minor points of clarification:

- Direct transmit to a repeater with good line of sight with a high power mobile and a good antenna should easily get you +60miles without problem and potentially 100 miles with the right conditions, etc. Most repeaters are public and all the 'codes' (eg frequency, offset, required tones, etc) are public and easy to find

- Specialized antennas (ie not verticals that radiate generally equally in all directions) like directional Yagis have a higher + more focused gain. ie, point them in the direction and the signal is radiated in that direction only (mostly) can help with greater distances

- Finding repeaters isn't a problem - buy AARL for Repeaters software - all the repeater data is loaded in the program and you just point to areas on the map that you will be in and it drives a list (it also programs my radio with all the required frequencies - very handy!)

- Once on the repeater, there - may be - additional options:

1) autopatch - used to patch into the PSTN for normal calls. May be restricted by owner (ie have to support repeater for access

2) Some repeaters have IRLP Internet-based, but radio-controlled patches that allow you to connect to repeaters anywhere in the world (that are equipped with IRLP). You dial a 4 digit access code - you need to know the codes = public. This is different than Echo Link which is software you use that allows computer to patch to repeaters (you won't be using this in the field) - computer - radio communication. IRLP is radio - radio communication.

3) Some repeaters are on (non-IRLP) linked repeater systems. These are true emergency back-up links b/c they don't rely on Internet, they use radio waves to link them. Some require a series of codes to open the next repeater and to 'jump along the chain' leaving the entire path open (ie people can hear you across the entire repeater footprint you are linked to). In other cases, a special sub-tone is used to trigger automatically opening a number of repeaters = you will be heard across the entire footprint. Both operate in my area and may in your as well.

If all of that fails, we then turn to HF. If that fails we use the flare gun and the signal mirror and if that fails we use the EPIRB and wait for the low pass of the C-130 (be careful, the lines on the parachute flares can burn and drop the flare on your head) ...or use a satphone....


Cheers, Hugh

[alia176]

Originally Posted by e9999

Soo, that made me wonder. If I'm in the middle of the Sonoran or Mojave desert or in some mountains away from civilization, how useful is that 2m (widely suggested here) going to be if I break down, for me to get ahold of CDan if a mobile 2m can only do 30 miles or so (I think). I imagine there aren't many repeaters in the middle of nowhere.

what you need to do in that situation is learn to fix your junk and limp out! UPS doesn't deliver to the middle of the Mojave. You've read the past trip reports from Cruiserdrew so you know the capabilities of these things.

cheers!