On Wed, Aug 19, 2009 at 12:23 PM, spencerhamons<[email protected]> wrote:
> James - thank you for taking the time to post this response. > I'm sure it took a while to do, but this is the most comprehensive > response I have seen yet. I'm not sure that this topic is really right for this reflector, but I'm going to keep pushing for OT2 use, so it is somewhat relevant. The NWAPRS reflector is a great place for discussions such as this. It's a group of APRS people from all around the Pacific Northwest, and you are definitely fitting that description. Have a look around the website for a start... www.nwaprs.info. One thing that might be a detractor, is that if you ask for an opinion there, you're going to get a bunch, and some may be contradictory to another... that starts up a discussion that can run away from the original question... > I will reply back to some of your points. I would suggest that you > go to http://aprs.fi and do a lookup on Bethel, Alaska. Don't look > at the "Map", but in the upper right corner, select "satellite". > I think that will give you a good idea of our area here in Bethel. Yeah, not much to look at... 8) I see the lovely Teleatlas road database is wonderfully aligned with reality. Can you point out where the 200 foot tower is located? > I'll answer one of your questions first, and that is the reason for the > 210 foot antenna height. <snip> > Therefore, we are going to put our local VHF and UHF repeater > antennas at the top of the tower when the work is done. Okay, I wasn't really asking the reason for the height, but rather what role the tower would play, especially with the D710 attached. I think I understand now... your house is a digipeater for now, but the TV station will become the main digipeater once the antennas are in place. > Remember, there are no other towns around us, so we need > to get everything that we can out of the equipment we have available. Hey, it's that way everywhere else as well... > Back to the placement of digipeaters. We anticipate that once the > primary digipeater is in place on top of the radio tower that it will be > our primary coverage device. What my concern is, and I think you > are correct that it will just be a matter of playing with it, is whether > or not mobile units placed on the periphery of town would be useful > at all. Our town is very small (see the satellite image), so although > I could see the potential of peripheral, fill in digipeaters helping out > the HT signals reach the main tower / digipeater / IGate, I'm just not > sure that they would be that beneficial. Umm, unless there's some weird RF vortex phenomenon up your way, there's no reason to put fill-in digipeaters on the periphery of town. "Town" is 5 miles across, from end to end. You should easily get HT coverage out 10 to 15 miles. Now, if you're talking about putting fill-in digipeaters 15 miles away from town, that might be useful. Put the digi in place, and try it out before you go crazy.trying to build a network. I bet you'll find things work quite well for you. That would be my plan if I were in your shoes. Leave your house up as an i-gate. > We want to be sure we can accomodate any operator in any > way possible. That was part of the reason for chosing the > Kenwood as a digipeater. We can utilize VHF and UHF, > depending on the equipment a rescuer has as well as > whatever antenna can get out the best given the conditions > on a specific day. Okay, let me poke some holes in your theory... If you install the D710 at the TV station, and configure it to work as a digipeater, you will be tying up one side of the radio on 144.390 most likely. That does leave the other side of the radio for voice work... just what you want. However, if you are using the second side of the radio on VHF, you will loose one receiver whenever the other transmitter comes up. If you are listening to someone on voice, every time the digipeater digis a packet, you will miss a portion of the incoming voice call... If you are talking to that same person, as long as you are keyed up, the digipeater is deaf, missing all the packets. A digipeater needs to be a dedicated part of the network. It can't be part time. Trying to use the D710 as a digipeater, and a dual band radio is folly. I would put a dedicated radio/TNC in place as a digi, and keep the D710 for use as that dual band radio with APRS capability. I'd look at tying the digipeater and or repeaters on that top antenna, and if you still have the lower antenna, hang the D710 off of that. You can get all the functionality out of the D710 that you are looking for, and still have the digipeater working properly. If you need to go to simplex, you have an antenna well located on a nice high spot. > There are a few uses that we would like to use APRS for. > Our radio club does quite a bit of work with the Yukon-Kuskokwim > Health Corporation during emergency drills, mass dispensing > exercises, pandemic drills, etc. We want to be able to use > the bulletin board and other capabilities of the system to > effectively move data during these exercises. Yup, can probably get that functionality nicely... have a look a d-rats... It's designed around D*Star, but you could use it to send messages and files around on the APRS hardware too. Not so good in a full APRS network, but on an isolated digi like your area, you can probably get away with it. Another subject for later... > Search and rescue is a major player, especially in the winter > here, and we would like to be able to send messages to the > search teams from a command post in town, as well as use > it for position reporting. We also help support the Kuskokwim > 300 dog sled race, and see position reporting as a big potential. All things that can benefit from APRS. > As we are setting up our system, our biggest concern is with > search and rescue. Although we are trying to increase licensure > of that group, only a small portion of the SAR team has an > amateur radio license. We are considering purchasing some > trackers to place on snow machines for some of the non-licensed > rescuers (we have some questions into the ARRL lawyers about > some of this). Don't worry about it... If you put the trackers on the machines under your callsign, and fire them up, there's no legal worries. The operators of the snow machines are not in care and control of the tracker. The trackers are running under automatic control. It's functionally the same as you running a digipeater under your callsign. It's all perfectly legal. (You may find someone who disagrees, but they are WRONG!) We've been over this a number of times on the NWAPRS sig, and it's run through the APRS sig many times as well... put them on the machines, and get out there. > Those that are licensed, we would like them to be able > to use all the functionality of APRS, not just position > reporting. The big issue here is safety. This is good to hear, there's more to APRS than just tracking the car. > These SAR groups can go 40 - 60 miles out of town out > onto the tundra to try to find someone who didn't make > it in from a trip. In mid- winter, 4.5 hours of daylight is > about all we get, so safety is a big consideration for this group. Okay, now you're putting some heavy demands on the equipment. I doubt you're going to get 60 miles out of a tracker back to town on a single hop. Now we are talking about needing to set up a self deploying APRS network. That's a place where a SARn-N network can be perfect. This is where the OT2M is the only unit out there to do what you need. The trackers can be set up to act as preemptive digipeaters, and as you get near the end of the digipeater coverage, you drop a digi, or have a snow machine stay at that point. The rest continue along until they run out of range of the extender. Drop another digi, and continue. Put this idea into your files, and we'll get back to it later. Let's get you on the right track with a regular digipeater. > Finally, point well taken on the what happens when all the APRS > stations are at the coffee shop on a Saturday morning, all > digipeating the signals. Good illustration. Toss the idea of having mobile fill-in digipeaters for now. You won't need them in town. SAR teams in the boonies are a different beast. > To answer your last question, we have 50 > not-so-well-equiped Hams. The usual mix... again nothing out of the ordinary. James VE6SRV
