Sunday, June 29, 2014

Testing the NET51TNC as an APRS Tracker

On the GPS tab, I turn on Smart Beacon and took it for a ride.. The Smart Beacon is the 3rd options from the left .. I've setup my tracker as 9W2SVT-9 with a red car icon ...

GPS tab
Here are my setup on 2 cigarette power supply powering the NET51TNC and my Wouxun UVD1P radio.. I have also setup the GPS (9600 baud) and connected a Skylab SKM53 GPS module on TTL to the I/O pins.

Power Supply, GPS I/O

From the picture below, I have mounted the small GPS module from Skylab SKM53 inside the car. This GPS module is really sensitive and can received GPS signal from insde the car.
GPS mounted inside the car

This APRS packet was bounced off a digipeater really far away ....

The below image shows a WIDE2 scenario where the APRS packets was repeated twice before reaching an iGate.


Tuesday, June 17, 2014

The 5-in-1 NET51TNC APRS WX/iGate/digipeater/Tracker/TNC/Bluetooth device

Three of us ( 9W2WHT, 9W2KHN and myself 9W2SVT ) ordered this item from Taobao, an 5-in-1 APRS wx station, networked iGate, digipeater,  Tracker / TNC and BT module finally arrived after a week.


NET51TNC with China handy cables

This little gadget from BH4TDV is a multi function device :- WX station, Network enabled, iGate, digipeater, tracker ( add your own GPS module ) and BT to android phones via APRSDroid.

Here are a summary of what it can do ...

1. When connected to the network / Internet via the RJ45 port, it becomes an iGate.

2. When disconnected from the network/Internet but connected to a radio, it becomes a digipeater.

3. When you connect an android app ( APRSDroid or others ) via bluetooth, it becomes a BT TNC

4. When you connect a TTL/RS-232 (jumper selectable) GPS to the I/O ports, it can act as an APRS Tracker

5. It can read sensors and becomes a weather station (WX) without the need of a computer.

Comes with data cable ( PS/2 connectors on both ends ) to connect to the mobile rig data port. We ordered the Kenwood / China based handy to connect to my Wouxun handy.

Below is the screenshot from APRSDroid connected to this NET-51TNC via BT TNC.

NET51TNC with APRSDroid

Below are some of the settings screenshots of NET51TNC :-

Status tab :-
net51tnc status
Network tab :-

net51tnc network
Beacon tab :-

net51tnc beacon
TNC tab :-
net51tnc tnc
GPS tab :-

net51tnc gps

Data Monitoring tab :-
net51tnc data

**** Updates : There is an english version of the software found at

Making Arduino UNO / atmega328 as an AFSK modem or TNC

This is a Micro APRS from this site ( ). I just get a few common parts and put everything together on top of a ProtoShield. 

Arduino AFSK modem/TNC

Once it was working, I made another one so that it can talk to each other over RF. The picture below are two Arduino UNO connected directly to test the Tx and Rx encoding/decoding.

Decoding APRS packets off the air on 144.390 Mhz.

The Arduino modem / TNC working and connected to my Wouxun handy.

Decal on my car - 9W2SVT

Printed this decal from a hobby and DIY shop in Jalan Peel.


Some antenna pictures I took on top of Bukit Bendera, Penang

Here are some pictures during my trip to Penang.

Also some maps from APRSDroid.

Added a L-shaped iron rod proper mounting pole for the Slim Jim antenna

I've mounted an iron rod and extend the antenna 1 foot away from the balcony for better transmission and reception. As you can see, I'm being surrounded my high-rise building at every angle. I'm on the 16th floor. 

My dual band 2m/70cm mobile antenna - Diamond MR77

Here is my dual band Diamond MR77 2.15 / 3.14 dBi gain antenna. The specs are 2m 1/4 wave and 70cm 1/2 wave antenna.

Playing with SDR using a RTL2832u with Elonics 4000 Tuner

My RTL2832 with E4000 tuner and PAL connector with UHF female at the other end for hooking up to the external antenna.

Terratec RTL2832 + E4000

My handy - Wouxun KG-UVDP1

Here is my dual-band handy from Wouxun KG-UVDP1 connected to Samsung Beam running APRSDroid and a DIY audio cable.

Wouxun UVD1-P

My first 2m radio & antenna

This is my first radio Kenwood TM-281 ...

Kenwood TM-281
and my first outdoor Slim JIM Antenna tied to my balcony ...

Slim JIM 2m antenna