an introduction to aprs

1

An Introduction to APRS

Presented by Scott Grimmett

2

What is APRS?APRS stands for Automatic PacketReporting System (although it isfrequently also called Automatic PositionReporting System.)

APRS can be used to track an object usinga amateur radio and a GPS receiver.

The position location information can beviewed on internet websites.

2

3

APRS Applications

Typical applications are:

• Marathons, races, events and publicservice

• Search and rescue• Family tracking• Weather data exchange and display

4

APRS Hardware

APRS needs three pieces of hardware

TransceiverTerminal NodeController (TNC)

GPS

3

5

GPS – Global Positioning System

A standard GPS unit with dataoutput port.

Uses 24 orbiting satellites topinpoint anyone's specificgeographic location.

GPS also provides ground speedand altitude measurements.

6

TNC – Terminal Node Controller

A TNC which is basically aradio (or “RF”) modem.

The TNC connects the GPS tothe transceiver. It convertsthe GPS data into AX.25Packet protocol to send viathe transceiver.

4

7

APRS TransceiverA VHF Amateur RadioTransceiver operating on144.390 MHz. (USA).

Should be a “transceiver” asAPRS uses a collision detectionsystem to know when to senddata.

Range of coverage depends onthe power of the transmitter andterrain.

8

Radios with Built-in TNCs

These radios are specifically designed tosupport APRS functions in a singlepackage. Just add a basic GPS unit and itis ready.

• Kenwood TM-D700A• Kenwood TH-D7A• Alinco DR-135T MKII with EJ-41U TNC

5

9

Built-in TNC configuration

TransceiverGPS

10

APRS TNCs

This full featuredKantronics TNCcan both transmitand receive.

“TinyTracs” aresimple “TransmitOnly” stand aloneAPRS TNCs.

6

11

APRS TNCs

This full featuredKantronics TNCcan both transmitand receive.

“TinyTracs” aresimple “TransmitOnly” stand aloneAPRS TNCs.

12

APRS Hardware

Terminal NodeController (TNC)

GPSReceiver

Transceiver

7

13

APRS Weather Stations

TransceiverTerminal NodeController (TNC)

WeatherStation

In a APRS weather station the GPS unit isreplaced by an outside Weather Station.

14

How does the signal travel?

Internet

InternetGateway

Digipeater

APRS System

8

15

Use the internet to plot location

16

Plot Location

9

17

Track Objects

18

Show APRS Activity in an Area

10

19

What is APRS.APRS receiver (GPS, TNC, Radio)APRS Mapping SoftwareMy systemTrack this weekBike event trackingRadios with TNC built inOther APRS systems.How signal travelsWeather

20

APRS

APRS needs three pieces of hardware:• A Transceiver• A Terminal Node Controller TNC• A GPS receiver

11

21

Radios with built in TNCs

These radios are specifically designed tosupport APRS functions in a singlepackage. Just add a basic GPS unit and itis ready.

• Kenwood TM-D700A (includes front panel display)

• Kenwood TH-D7A (includes front panel display)

• Alinco DR-135T MKII with EJ-41U TNC

22

APRS Weather Stations

In a APRS weather station the GPS unit isreplaced by an outside Weather MonitoringStation.

12

23

Gateway Station

Internet

An amateur radio stationused to connect otheramateur radio stations tothe internet is called agateway.

Gateway

24

It uses graphical maps and other data displays.

All communications use a “one-to-many protocol”so everyone is updated in real time.

Uses Generic digipeating so knowledge of thenetwork isn’t required.

APRS turns packet radio into a real-time tacticalcommunications and display system foremergencies and public service applications.

13

25

APRS consists of a very large land based wireless network.Almost 30,000 users around the world.

This network works via RELAYS every 20-30 miles called“digipeaters.” And Globally via IGates to the internet.

APRS is also used via some of the Amateur Satellites.

It is also used to monitor telemetry values of weatherstations for the National Weather Service (NWS)

APRS has the capability to quickly relay telemetry values toresearch centers without the Internet.