Richmond Amateur
Telecommunications Society

W4RAT · Richmond, Virginia

Celebrating 50 Years · 1972 - 2022 



NOTE:  RATS ceased further investment in its APRS network effective November 2019.  The APRS.RATS.NET information provided on this web site is being maintained for reference until all W4RAT digipeaters are retired.  Several club members remain active in APRS and the Technical Committee is happy to help connect members wishing to get involved in this aspect of the hobby as a user or a digipeater operator.

RATS APRS Network

Richmond's APRS network began almost 20 years ago with a digipeater in a hotel elevator shaft.  In a two-year period from 2006 to 2008 what started as VA-APRS expanded to become the largest "single operator" APRS network in the state while under RATS care.  Today, there are 3 RATS-affiliated digipeaters still in operation.  [More History]

What is APRS?

The Automatic Packet Reporting System has, quite literally, from the time of its inception in the mid-1990’s, taken the Amateur Radio world by storm.  Ironically, storms like hurricanes and other weather disasters, were the first crucibles that proved the value of a simple, reliable communications system that allowed both “tracking” of individual stations as they moved about, and also the simultaneous transmission of all kinds of important data, from weather updates to medical emergency information, in a way that could be shared by every station equipped with the basic level of equipment, whether they be mobile, or fixed stations.  Whether you simply use an old 2-meter HT and a tracker module along with your GPS unit to fix your position on a map back home while hiking, or pass on vital emergency information during a public event or weather emergency, chances are you already have most of what you need to get into APRS.

APRS was developed by Bob Bruninga, WB4APR.  From his website:

"The Automatic Packet Reporting System was designed to support rapid, reliable exchange of information for local, tactical real-time information, events or nets.  The concept, which dates back to the mid 1980's, is that all relevant information is transmitted immediately to everyone in the net and every station captures that information for consistent and standard display to all participants. Information was refreshed redundantly but at a decaying rate so that old information was updated less frequently than new info.  Since the primary objective is consistent exchange of information between everyone, APRS established standard formats not only for the transmission of POSITION, STATUS, MESSAGES, and QUERIES, it also establishes guidelines for display so that users of different systems will still see the same consistent information displayed in a consistent manner (independent of the particular display or maping system in use)."

APRS, quite simply, is the transmission and reception of digital location data obtained via GPS over an amateur radio frequency.  This information can be viewed through the use of a TNC (Terminal Node Controller) and a computer terminal (desktop, laptop, or even a PDA).  The tracking information is processed by any number of freely available programs, and superimposed on a map of the area.  Your call sign, and those of other operators online, show up on this map, and will track along the map if you are in motion. In addition to this basic location information, APRS can pass along many different kinds of data along at the same time, ranging from messages (from your station to other individuals, or the whole network), to weather information ( you can even interface weather stations to APRS), and even such specialized information as emergency beacons and National Traffic.

APRS Operating Guidelines

The following local operating guidelines have been adopted and users are asked to adhere to the following:

  1. Set your DIGIPEATER PATH to "WIDE2-2" for fixed or "WIDE1-1,WIDE2-1" mobile stations.
  2. Please do not exceed 1 location-beacon per 3 minutes. Controllers will automatically ignore more location-beacons in excess of every 2 minutes.
  3. Enable the "MIC-E" transmission format, this is a compressed beacon format and is more effecient.
  4. Limit your output power to 25 watts or less.

Digipeater Operational Guidelines

Already running a digipeater? Contact the Technical Committee and we'll help convert your older controller to the newer APRS standards.

  1. High-Gain antenna at a minimum of 100 feet above ground, or any location suitable for a local-coverage VHF repeater
  2. Radio with 25-30 watts output
  3. Any controller:
    • Commercial solution: USmartDigi digipeater daughterboard for the TNC-X TNC. This is the recommend controller for the APRS.RATS.NET network
    • Linux solution: Linksys NSLU2 or WRT54G device modified for Linux with DIGI_NED software
    • PC solution: Any KISS-mode TNC connected to a PC running DIGI_NED (cygWIN Linux emulator required)
  4. Emergency Power (72 hours or more)

Controller Rules for APRS.RATS.NET Nodes

BEACON RATE: 15 minutes (30 for fill-in or smaller coverage nodes)

PATH: WIDE2-1 for major nodes, "direct" for fill-in nodes

No single path may exceed 3 (ie: WIDE3-3) and no path count may exceed 5 (ie: WIDE2-2,WIDE3-3)

Excessive Paths are re-written to WIDE2-2 - IN BETA TEST

Coordinate Blocking of a defined NORTH/SOUTH/EAST/WEST boundary (Geo-Fencing)

Throttling of LAT/LON beacons with intervals of less than 120 seconds (Message Packets are exempted from throttling rule)

No WIDE/RELAY/TRACE allowed

RATS APRS History

Richmond's APRS network began almost 20 years ago with a digipeater in a hotel elevator shaft.  In a two-year period from 2006 to 2008 what started as VA-APRS expanded to become the largest "single operator" APRS network in the state while under RATS care.  The original network was started by Peter Martin K2VIZ and Jay Silvio N9WMU (SK).

The first nine RATS-owned or RATS-affiliated APRS digitpeaters were:

  • W4RAT-1 Chesterfield, sponsored by WCVE/CPB
  • W4RAT-2 Coatesville, sponsored by Peter Martin KF4VIZ
  • W4RAT-3 New Kent/Barhamsville, sponsored by New Kent County
  • W4RAT-4 Goochland/Shannon Hill, sponsored by Ralph Fetty W4FEG
  • W4RAT-5 Prince George, sponsored by Rob Turner KG4YJB and Brad Price KI4BWJ
  • W4RAT-6 Downtown Richmond, sponsored by VDEM and Terry Hebert KG4GLS (SK)
  • W4RAT-7 St. Stephens Church, sponsored by Peter Martin KF4VIZ
  • W4RAT-8 Victoria, sponsored by Peter Martin KF4VIZ
  • W4RAT-9 Buckingham/Dillwyn, sponsored by Gordon Winn WW4GW

Major support for the original APRS build was provided by the following individuals & organizations:

  • Rob Turner KG4YJB
  • Brad Price KI4BWJ
  • Jay Silvo N9WMU (SK)
  • Ralph Fetty W4FEG
  • Melodie Martin KF4ZGF
  • Peter Martin KF4VIZ (now K2VIZ)
  • Terry Hebert KI4GLS (SK) & the Va. Dept of Emergency Management
  • Gordon "Bubba" Winn WW4GW
  • Max Lind
The three remaining APRS digipeaters are privately owned and maintained but continue to operate under the W4RAT call sign.

Updated 12:12a 2022-10-09 by KG4PEQ
Updated 9:29a 2022-10-29 by KG4PEQ -- additional historical information

Richmond Amateur Telecommunications Society, Inc. (RATS) is a 501(c)3 non-profit organization. PO Box 70613, Henrico VA, 23255

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