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Joined: Tue Apr 30, 2013 9:50 am

Open source APRS display unit with navigation ideas

Sun Nov 15, 2015 6:42 am

Some ideas i have for a carputer that has built in navigation and support for APRS,and connection to a vhf/uhf radio. This is a template for the idea,its hardware and software functions.

The GIT is located here:

I hope someone wants to contribute.

Hardware: Touch screen with mount that fits in a cars 2x DIN (180x100mm) hole.
A viable unit is the Icarus 2DIN housing, it has a touch screen and a rotary encoder,on/off switch and a 4 port active usb hub with connectors in the front. It also has a metal box. It does not have the possibilities for detachment so it is not so attractive for car burglars.
USB hub with 6 ports for under the dashboard modules.
A 12V to 5 V converter is also needed,this can be on board if a PCB is made.

Rasberry Pi B+ or better.
USB sound card for voice directions from navigation software.
TNC-Pi 2 for those radios that does not have a built in TNC. (

USB or on board RS-232 converter for interfacing to radios Terminal Data port.
Some never radios uses (ex Yaesu FTM-400DR) a usb cable with a something that i am sure is a built in converter.
USB port with optional rs-232 converter for CAT communication with the radio.
GPS receiver with external or internal antenna:
UBLOX NEO-M8N,Supports: GPS,BeiDou WAAS, EGNOS, MSAS and is Galileo-ready Good RFI/tvi shielding.

Optional hardware: RTL2832U based usb recevier, this one supports DVB-T and FM and DAB+ (retrofit of Glass mount antenna possible?)
Good quality 4x50W audio amplifier with interface plugs to typical car speaker plugs.
Blue-tooth, some radios already has this built in,should be possible to pair with a blue tooth headset.

Automatic brightness regulation with light-dependent resistor(useful for night operation)

Basic Software features and options:
Navigation and routing to addresses and gps coordinates,other APRS stations(when they are stationary for the moment). Display distance and bearing to the nearest APRS station with adjustable range filter(display only units that is inside xx kilometers,also displays beaconed message.
Display altitude and GPS status. GPS track logging. display speed/bearing of travel.
Stations that are inside the filtered range but outside the current zoom level is displayed in the right side bar on the units navigation/map display. If the station transmits a message with a frequency, double tapping on the message transmitted causes a CAT commando to be sent to the radio, so it tunes VFO2 to that frequency. Tapping it again returns it to your "home frequency",that is stored in the options/settings dialogue.
Hamlib can be used for software interfacing of many radios.
API documentation:

About APRS: ... ing_System The symbols and misc info about them is on this page:
Information on the APRS protocol can be found here:

Compatibility with (import of database from file or via wlan connection?)
Database stored on SD card. Automatic switching to navigation map if the vehicle starts moving, or no input from the touch device is detected. I suggest a timer of 5 seconds.

compatibility with maps from openstreetmap:
Suggested routing software:
GIT repo here:
Update of map data via wifi or other means.
I don't know if it can display APRS symbols. The software can possibly be customized to do so, or a "digital layer" that is displayed over the navigation map created.
(take a peek at )

Optional software functions:
DAB/FM tuner
Media player (MP3 and common formats from USB key)
Audio media level control.

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