“Worlds smallest APRS transceiver with TNC” offers many applications. Matchbox-sized, built-in GPS receiver.
The transceiver can not only be used as APRS tracker and receiver for APRS data, but also as TNC (KISS protocol) for computer.
The graphical OLED display (128×64 pixel) shows received APRS packets such as position reports, APRS messages and status information.When receiving position reports the distance and cardinal direction to the sender is shown.Each of the four most recently listened in stations, including distance and cardinal direction as well as received messages are saved and can be retrieved via menu.
The own GPS coordinates are also shown, allowing the PicoAPRS to be used as a GPS receiver as well, for example for Geo Caching.
It’s possible to save a fixed GPS position. This position is used when GPS positioning is not working. The fixed GPS position is then only used to show distance and cardinal direction of received stations. A speedometer is also included. You can choose to have your speed displayed as either km/h, mph or knots.
All handling is done with two push buttons. With the help of a versatile menu system the transceiver can be individually configured and operated without using a computer.
The device comes almost fully preconfigured. Just save the call sign and you’re ready to go.The transmit power is approx 1 Watt and can be switched down to 0.5W. The own position data is transmitted as a compressed MIC-E APRS message to keep transmit duration as short as possible. This also helps to save battery power. Of course received messages in compressed MIC-E can be decoded and displayed as well.
The built-in 850mAh LiIon battery allows operation up to 10 hours  depending on configuration.
The HF receiver can be deactivated to save a lot of power, the Pico-APRS then functions as a pure APRS tracker. To extend battery lifetime even further the GPS receiver can be turned on and off in programmable intervals and the display can be dimmed. While charging the charge current is being displayed. A buzzer is used for alarms and confirms button touches (can be turned off).
The PicoAPRS can now fulfill functions of a POCSAG pager. In contrast to a normal pager the device can even send an acknowledgement when receiving a message. This shows the sender that his message has been received successfully. Messages can be sent directly to other radio amateurs ion the APRS system, or even to E-mail adresses. A simple reply function allowes the use of pre-made standard replies. Just select “Reply”, select the prepared text and send. Ready!
While en route you can send a link to your position on aprs.fi to your destination by e-mail. With this function the people you are visiting can easily see where you are and when to start brewing a fresh coffee. This works worldwide without a mobile phone system, without roaming bills, without a mobile phone. The own callsign including SSID is embedded in the link, the recepient just needs to click on the link.
The new tactical ‘follow’ function is helpful for example when skiing with a partner. Just select the callsign of the partner, select ‘follow’ and you will continously see the position and direction of the followed station. When receiving new position reports the display is updated automatically. Or you can use this function while driving in a convoy with multiple vehicles.
The built-in micro USB connector is not only used to charge the built-in battery and for upgrading the firmware, but also to use the tranceiver as a USB-GPS mouse or as a TNC at a computer. This allows you to set up your own APRS Digipeater or iGate in a breath! We will provide a guide for this in the near future. Via a menu you can choose wether the PicoAPRS should automatically turn on once connected to a USB power source. This is especially useful in cars when your power source is switched on upon startin the car.
The transmitter utilzes a 7-pole low pass filter to suppress unwanted harmonics. The main processor is well known from the Arduino world, it’s an ATmega 1284p. The current software uses a little more than half of the available memory, this allows for a lot of further developments in the future.
The tiny size of just 33 x 58 x 24 mm is close to that of a matchbox. The weight (without antenna) is just 52g. This is perfect to carry the Mini APRS Transceiver with you all thetime, whether on a hiking trip, on a journey with your bike or boat or even when skiing.
The Pico-APRS was developed by Taner Schenker (DB1NTO).
 Depending on how frequently the position data is to be sent, whether APRS packets are to be received, whether the GPS receiver should be switched off automatically when not in use, and how often the display can be switched off
Menu items (to be extended):
- Device off
- Recently listened in stations
- Received messages
- APRS symbol
- GPS status and display of GPS data: coordinates, absolute altitude, Maidenhead (QTH) LOCATOR, GPS date, number of satellites, course
- USB mode (AUS, GPS, TNC)
- Save current position as “default position”
- Transmit power (1 Watt / 0.5 Watt)
- Send Beacon
- Time zones for adjusted displayed time
- MyCall, SSID
- Receiver exchange ON/OFF (OFF = just tracker for sending position report)
- Autoclose (closes received messages after an adjustable time automatically)
- Display timeout (“screensaver”)
- GPS power saving (ON/OFF)
- Display contrast (low / high)
- APRS comment text
- Information display
The PicoAPRS ships completely assembled. No charger or antenna included. Thanks to the standard micro USB connector, the charger of any newer mobile phone can be used for charging. Alternatively, charge with any USB charger or USB port of a PC. For suitable USB cables see accessories list.
Any antenna with SMA connector can be used as an antenna, for recommendations see our accessories list. The tiny device makes you want to use a tiny antenna as well, but small antennas have a comparatively poor efficency, of course, and we only have 1W of transmit power. When used in a vehicle, an external antenna is recommend, for example a magnet base antenna.
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