So You Wanna Run A Mobile Station
So you wanna run a mobile station. You've got a few options to choose from these days and it'spretty hard to go wrong. This document won't cover what options you've got, but rather how to configure them. Something to bear in mind is that APRS traffic takes place on 144.390MHz. For those people storm spotting or using 2m FM voice for emergency operations, your APRS setup may desense or affect the peformance of your 2m rig during nets. As such, you may wish to coordinate with your storm spotting groups to decide the best course of action in trying to use APRS with 2m FM voice. The goal of with regards to mobile arrangements is to provide coverage for mobile rigs running 5 watts. While it is possible to run higher power mobile setups, we feel that 5 watts is the magic number in order to be able to support 2m FM voice and other activities while mobile. Your mileage may vary. Suggestions for running a Tinytrak The TinyTrak and Opentracker have become a popular option for those wishing to run a low cost "homebrew / homebuilt" APRS setup. These tracker have many useful features and take the place of the TNC. The suggested configuration of the TinyTrak is to beacon no more than every 3 minutes. This is especially important if the "Smart Beaconing" feature is turned on. If the Smart Beacon feature is turned on, our suggestion is to beacon every 3 minutes if your course stays relatively straight and to beacon if your direction changes by 90 or more degrees. If you think about it, if you're traveling down the interstate, it's pretty safe to assume that you're going to still be on that interstate 3 minutes later. And if your course changes direction then you're going to beacon anyway (hopefully not by 90 degrees on the interstate). Options to consider for your UNPROTO path Please note the following configuration is no longer suggested and not be supported on the Middle Tennessee area digis: RELAY,WIDE,TRACE It was announced at the Hamvention 2003 APRS forum that TRACE is deprecated. In 2005 the APRS SIG mail list hammered out the New n-N Paradigm. This new basically boils down to this: RELAY is replaced by WIDE1-1 so that even older firmware TNCs can work in the new paradigm and not cause too much congestion.WIDE is replaced by WIDEn-N The n=N in your settings butN counts down in the packet as it is digipeated. Keep N as small as possible. TRACE is replaced by (TNn-N for Tennessee, KYn-N for Kentucky, ALn-N for Alabamea, etc.) This is used to keep packets from digipeating outside your home state. There are several options to consider for your UNPROTO path. For those not in the Nashville area, you need to find out if your digi's support the WIDEn-N protocol. If they do not then there is no point using the WIDEn-n path. While a WIDE digi will pick up and retransmit the WIDE portion of the statement, it will not decrement the counter accordingly. Likewise, if you will do a lot of traveling and cannot confirm the status of digi's in the vicinity of travel, then you may wish to plan your path accordingly. If you're a homebody and never leave Nashville, well, then you can use WIDEn-n and call it a day. Nashville is WIDEn-n compliant. Here are some UNPROTO configurations: WIDE2-2WIDE1-1,WIDE2-1WIDE1-1,WIDE2-2 In effect, all of the statements above are the same. All state that any station with an ALIAS of RELAY should act upon your packet by RELAY'ing it, preferably to the nearest digi. ALL UNPROTO statements state that the nearest WIDE digi should pick it up, and pass it along (retransmit), where if another WIDE digi hears it will retransmit it too. However, any other WIDE's will not act upon the packet because both WIDE statements were fulfilled. At that point the mobile station is "2 WIDES out" and hopefully into an Igate accordingly. TRACE is a WIDE but instructs the digipeater to do callsign replacement if it's capable of it. All of the UIDIGI and KPC3 type TNC's with appropriate ROM's will do callsign replacement on any WIDE statement, with or without the TRACE statement. However TRACE has been deprecated by the advent of WIDEn-n. Thus, do not use TRACE. TRACE was announced as being deprecated at the 2003 Hamvention APRS forum. WIDE2-2 is in effect WIDE,WIDE. However, if you notice you've saved yourself 2 characters. As a result, the packet is slighly shorter. This becomes important in heavily congested APRS nets. Bruce Martin commented that for the Nashville area, this should be more than enough:
The RELAY,WIDE,TRACE,WIDE2-2 I have been using 5 years ago on my mobiles can now be shortened to WIDE1-1,WIDE2-1 and it will still get me into Atlanta's local RF network about 1/3 of the time. WIDE2-2 should be enough to make it to an Igate and get into the APRS-IS system. Please use WIDE2-2 wherever possible. Yo