SVTrackR 1.62 : Dashboard speedometer & APRS Decoder

SVTrackR I2C LCD

One of my users suggested that I split the display from the APRS Tracker so that he can placed the SVTrackR together with the handy below the seat. I liked this idea and explore the unused I2C pins on the Arduino Mini Pro.

Once I found out that the I2C can goes up to 6m of length, I made a 1 meter cables and started my tests on the Eduboard I built with Serial and I2C header pins at the bottom right of the blue PCB.
I have also connected a APRS Modem to the Serial Rx,Tx pins.

SVTrackR 162 on Eduboard

Once I finalised to use the blue 16x2 I2C LCD, I search on Thingiverse for a 3D printed casing. I found this one below suitable and ask around for pricing and where to get it printed.

16x2 LCD I2C 3D casing

As I made my codes with #ifdef definations for OLED, I just added more #ifdef for 16x2LCD and format the display according to the size of the LCD, 16 characters by 2 rows. As these screen are physically bigger than the 0.96 OLED, the resolution is only 16x2 text whereas the 0.96" OLED can goesd up to 7 lines of 25+ characters.

As my main screen should be the large digital speedometer with number of satellites being tracked and heading in degrees, I will rotate to 2 other screen for other statistics like Rx, Tx packets, distance to base and altitude from the GPS receiver.

In order to displayed decoded packets, I wrote a checking to display the decoded packets for 10 seconds before switching back to the speedometer.

Below are some of the images taken from my dashboard, it fits nicely with the large number displaying the speed or other info.

SVTrackR on dashboard

SVTrackR decoded packets

16x2 I2C LCD during initial tests

I am still in the process of getting a 3D printed casing for this.

Tuning HF antenna with SWR Bridge and Rigol Oscilloscope

After viewing this Youtube video from W2AEW on #112: Use an Oscilloscope and Signal Generator help tune an HF Antenna, measure complex impedance, I decided to do a similar SWR bridge with a AD9850 as a signal generator.

Front of SWR bridge

Back of SWR bridge

SWR bridge with 3W 50ohm and 2x1K resistors

The actual circuit was on the above mention Youtube video.

SWR bridge mounted on Dremel Vise

Arduino + AD9850 + 8digit 7segment with VFO

I had the AD9850 on top of the Protoshield with a large 8 digit 7-segment display as the signal generator frequency with a rotary encoder as a VFO.

Sinewave of 50ohm compared to 50ohm terminator

Almost match impedance

The connection from the SWR bridge are BNC connector with a T-joint to the Rigol DS1052E with a 50ohm terminator. This ensure both ends are 50ohm terminated.

 To check the HF antenna impedance visually, turn VFO to the desired frequency and visually check the yellow (50ohm reference) and blue ( antenna ) sinewave. The above image is an almost match impedance. Once the two sinewave are close enough, turn the coax switcher to the IC-7200 and the SWR reading will be quite low.

Unmatch impedance

The above is an example of an unmatch impedance, with such big differences in the sinewave, it is almost certain the SWR reading on the IC-7200 will be very high.

Icom IC-7200

Finally got my first HF rig, a Icom IC-7200 (in Feb 2015) ..

MX200 Tuner, IC-7200

The Icom IC-7200 comes built-in with USB soundcard and IF DSP, the two features that are mostly found in higher end HF rigs..

Icom IC-7200

IC-7200 with MX200 Tuner

Power Supply, IC-7200 and MX200 tuner

KL Foxhunt and Emcomm APRS booth

Emcomm GoBox 2015

Here are some pictures of items displayed in APRS booth during KL foxhunt and Emcomm event in Kuala Lumpur.

RPi + aprx , SVTrackR + Maps, SVTrackR + OLED

Various APRS gadgets

Team Ham United

Ham United GoBox

APRS Arduino with map display

APRS Map on 2.2" TFT

While reading the chapter on Marinus: An APRS Display from the Ham Radio for Arduino & Picaxe by Leigh L. Klotz, Jr, WA5ZNU. I decide to give it a try over the weekend.

Ham Radio for Arduino & PICAXE

Initially it sounded complicated but after looking into my inventory ( Arduino, TFT display, SD card and APRS modem ), I have ALL the similar items needed to do this project.

I replaced the Arduino UNO with a DigiX , an enhanced Arduino DUE with Wifi, SD card, nRF and many more pins. The reason for this was for both mcu power, flash & memory storage and operating voltage of 3.3V as most of the TFT out there runs on 3.3V.

The next, I replaced the Adafruit display shield with a bigger and commonly used  2.2" TFT / ILI9341 (320x240) that runs on SPI. The Arduino forum here have lots of info on this display. This display runs on 3.3V only. As I have gotten this 2.2" TFT working on Adafruit GFX library before, it is just a matter of hooking up the pins correctly.

The SD card slot was built-in to the DigiX on pin 87 as Chip Select (CS). Nice...

MicroAPRS modem

The last piece, instead of Argent Radio Shield, I'm using an Open Source version of Arduino MicroAPRS modem by markqvist from unsigned.io. The above is a picture of the MicroAPRS modem board I made on DIY PCB.

For the library, DB1NTO modified the ArgentRadioShield library for the MicroAPRS for decoding the normal and compressed packets functions.

All the main codes remains the same as I just modified the TFT & ArgentRadioShield library only.

The image below are the whole system, DigiX with SD card, 2.2" TFT display, 5V to 3.3V from the MicroAPRS modem to the Serial3 of DigiX.

Marinus on DigiX / MicroAPRS

With help from the author WA5ZNU, I was able to generate the OSM map tile for 320x240 to match my 2.2" TFT display. Since I'm using a "bigger" Arduino with lots of memory, I generated a 7x7 tile to be stored inside the SD card.

OSM 7x7 map tiles

With everything setup, I put everything inside a plastic box and go for a ride. Below are some of the pictures and decoded callsigns on the maps.

APRS Map decoding my 9W2SVT-8 packets

APRS Map inside a plastic box

9W2SVT-8

9W2RUT-2

Summary hardware :-

• DigiX with SD Card http://digistump.com/products/50
• 2.2" TFT ILI9341 320x240 ( search on ebay.com )
• MicroAPRS modem from markqvist

Special thanks Leigh L. Klotz, Jr, WA5ZNU for the great article and his assistance to get everything up and running. Markqvist for the MicroAPRS modem and Taner DB1NTO for the modified MicroAPRS library to support for packet decoding for normal and compressed packets.

Summary Links :-

• http://hamradioprojects.com/authors/wa5znu/+marinus/
• MicroAPRS modem
• Marinus DigiX/DUE codes on pastebin.com
• Arduino SVTrackR
• MicroAPRS library for packet decodes
• Arduino Forum on 2.2" TFT

Updated SVTrackR with mini 0.96 OLED display

After a few months of testing and development, I have reach a milestone of version 1.0 with all the necessary functions and features.

SVTrackR with OLED

The functions and features of this APRS Tracker called SVTrackR are :-

• Super bright 0.96" mini OLED display
• Decodes mic-e / compressed packets
• Calculate distance to station from received packets
• Calculate bearing to station from received packets
• Display two decoded packets in multiple lines
• Decodes and display messages for the callsign
• Top section display GPS lat/lon and number of satellites
•  Lower section display important counters, speeds, heading and altitude
• Enhance Smart Beacons 
• Calculate distance to base station location
• Display uptime / minutes since power-up
• Sequence number of every packet to detect packet loss
• Byte saving by sending status every 10 packets

SVTrackR message

The OLED screen are bright enough during the day and are made for you to glance it during stops. It was NOT design to view it during driving as the text are too small.

The mic-e / compressed packet was decoded as 9M2NIA-9 was 142 degree, 6km away from my current location.

SVTrackR mic-e decoded

Summary links :-

Initial blog entry on SVTrackR
http://9w2svt.blogspot.com/2014/07/building-open-source-arduino-aprs.html

My repo on github :-
https://github.com/stanleyseow/ArduinoTracker-MicroAPRS

Cheras APRS Fill-in Digipeater Installation - 9W2SVT-1

This is a short entry on my team's installation of a 9W2SVT-1 digipeater at north of Cheras. Due to the blind spot at north of Cheras that was not covered by 9M2RPN and also the fact that my parent's house is on top of a small hill at around 80m altitude, I have decided to install a APRS digipeater with the help of other APRS Studio members.

Panoramic View from balcony

This is the panoramic view of my balcony looking over the entire Kuala Lumpur ( now blocked by trees ) and Bandar Tun Razak on the left side of the picture. With a clear view of downtown, this makes a good location for a fill-in digipeater location to compliment the coverage of 9M2RPN.

A bit of story about the antenna used here ...

1/4 wave ground plane

The first time I saw such weird looking antenna was at EMCOMM Go-Box event organised by MARTS. It is a 2m quarter wave ground plane antenna with four ground plane legs.

This four-legged quarter wave antenna was donated by 9W2KHN for this fill-in digipeater. The antenna was made by Pak Razif, 9W2JQQ.

1/4 wave ground plane

1/4 wave ground plane

As I'm more of an electronics and hardware programming fellow, doing drilling and physical hardware installation was not something I am familiar with. Luckily, within our group, APRS Studio, we have people with a wide range of skill-sets including antenna installation.

Below are 9W2CEW, 9W2KHN and 9W2WHT helping out with the digipeater installation on a hot and sunny day.

Below are the guts of the APRS digipeater powered with the BH4TDV NET51TNC as the digipeater and a TYT F8 as the radio. Both the radio and NET51TNC are powered by a 12V SMPS.

I plan to power up this digipeater using solar power and 12V battery in the near future.
The completed installation at the front of the roof.

1/4 wave ground plane

1/4 wave GP installed

After almost a week, here are the coverage area of this fill-in digipeater from aprs.fi

9W2SVT-1

Special thanks to APRS Studio team members 9W2CEW, 9W2KHN and 9W2WHT for the antenna installations, tools and donation of this weird looking but good performance antenna to make this fill-in digipeater possible..

If any APRS users driving along south of KL, Loke Yew highway or Sg Besi highway, do drop a few packets to this digipeater ..