Portable APRS Unit

Here is a pic of my Portable APRS unit that I've also used to test my Raspberry Pi TNC setup to ensure it is working OK:

You'll notice the high quality blue elastic that holds the Mobilinkd TNC to the back of the Yaesu VX-6R radio (grin). The cable was also purchased from Mobilinkd and I'm running APRSDroid on my ASUS Android tablet. The tablet is connected to the TNC via a Bluetooth link. You can see the map displayed on the tablet, however I usually run it in log mode to see  all of the traffic that it receives or transmits.

Raspberry Pi TNC & APRS

I've finally got my RaspiTNC up and running on my Raspberry Pi. It is hard to tell from the screen, but I'm running Xastir APRS software. The APRS (Automatic Packet Reporting System) is a wonderful project led by Bob Bruninga, WB4APR, APRS. Essentially APRS is digital communications for Amateur Radio operators. Here is my home iGate station with Xastir running on the screen:

Here is a closer look at the radio and Rasperberry Pi & TNC:

The radio is showing APRS, which is the memory name for 144.390MHz, the North American APRS frequency.

A closer look at the brains of the system:

The red board is the RaspiTNC, & the green board just below is the Raspberry Pi. Just below that in the somewhat clear case is an external USB hub to power everything and below that is an 8 port switch to hook everything up. 

**** Please ignore the very, very poor job of soldering the capacitor & resistor to the 9 pin SubD connector on the RaspiTNC. This is what happens when you are in a hurry……

However I am happy to report that the TNC receives data packets via RF and transmits them to aprs.fi, and also receives packets from the internet and sends them out via RF.

You can see the APRS J-Pole antenna that I used in a post about 4 weeks ago. it is omnidirectional to provide fairly even coverage around Irricana.

If you want to see where my station is from anywhere in the world, click over to aprs.fi and track call sign VE6RBN-1 which will zoom right into my rig show here.

Raspi Block Heater Control

Well, I have a Raspberry Pi controlling a 5VDC relay, which in turn controls a 120VAC Relay which can then turn my vehicles block heater on & off. For those of you who don't live in the colder Northern climates… a block heater is an electric element that is positioned within the water jacket of your automobile engine. When the temperatures drop below -10C to -20C, the engine is cold, the engine oil is much thicker, the battery loses some of its capacity, and starting can be difficult. When we talk of plugging our cars in, we're referring to plugging the block heater in to provide heating (much like a hot water kettle) for the engine so that it will be much easier to start at those frigid temperatures. My first attempt:

You can see the Raspberry Pi in the upper left hand corner, and the 2x5VDC relays (blue) just above it.  The 5VDC relays can safely be driven from the Raspi's GPIO pins and they can safely trigger a 120VAC relay that will power the block heaters. You can see the 2 x 120VAC relays on the DIN rail just above the 3 white/grey circuit breakers. There is an advantage to using these relays (commonly known as ice cube relays, because they are about that size), and that is 1) there is an indicator light to tell me if it is powered on and 2) there is a manual lever that I can move to manually activate the relay for troubleshooting purposes. Also, if for some reason, my Raspberry Pi was not running, I could manually activate the relays to power the block heaters continuously to ensure my vehicles start in the morning. There are 2 sets of relays to power 2 different block heaters in 2 vehicles.

The only problem with the above setup is that if there is a power failure during the evening, the Raspi's SD card may become corrupted and not restart when power is applied. I find this happens on occasion and I assume it is because the SD card is being written to when the power fails.

So version 2 includes my thoughts on a UPS that I've talked about here on this blog. I've installed a power supply (upper right) and 6 x AA batteries in a holder mountain just above the Wall Adapter on the right.

Now the 12VDC wall adapter powers the power supply (small circuit board to the upper right of the DIN rail) through a 1N4007 diode. Also the 6 x AA (6 x 1.5VDC = 9VDC) batteries are tied to the power supply as well through a 1N4007 diode. Normally when the wall adapter is working, it's diode is forward biased and the power supply is supplied by the wall adapter. Should the House Power fail, the voltage will drop until it reaches 8.3VDC (9VDC from the batteries - 0.7VDC to forward bias that diode). At this point the Raspberry Pi power supply will be powered from the batteries.

Our power outages occur fairly frequently (several times a month), however they are short lived. I am hoping this battery pack will last me thru the winter…..grin.

I'm running the WebIOPi software which allows me to have the block heaters turn on and off via preset times, as well as through a webpage on my smart phone or tablet. Thanks got to Eric Ptak (trouch) who is the author of this wonderful software, WebIOPi

Raspberry Pi UPS

I've had an ongoing issue with my Raspberry Pi's corrupting the SD card if the power failed during a write cycle, at least that's my assumption. On occasion, after a power outage, I cannot access the Raspberry Pi and have to reboot it. By watching the terminal display, it often indicated a kernel panic and I know that I have to re-write the SD card. About 10% of the time I cannot and have to throw the SD card out.

Most often, it seems that the power outages last for a brief period of time. So I went looking for a short term backup solution. My first thought was to go with rechargeable batteries, and I may still follow this route, but for now I've settled upon standard alkaline batteries to provide my short term coverage.

I've come up with the following circuit to prevent power loss to my raspberry pi's. I use a 12VDC wall adapter together with 6x1.5VDC (AA) batteries. Both feed the 10-30VDC > 5VDC power supply through diodes. My reasoning is that as long as the wall adapter is working, it will supply the voltage & current to the power supply, since the battery diode is reverse biased. If I lose utility power, the wall adapter voltage drops to zero, and then the battery diode becomes forward biased and supplies the voltage and  current to the power supply.

I have sourced the power supplies & wall adapters from China. 6 cell AA battery holder from my local electronics store and using 1N4007 Diodes to provide the isolation.

APRS J-Pole Antenna mounted

Well, last week I was finally able to get up on the roof and mount my J-pole antenna which is tuned to 144.39MHz for the Amateur Radio APRS frequency.

It is mounted right above my Television Yagi antenna and time will tell if it interferes with our television signal.

Makin' the LED Blink!

Yeah, I know it is the programming equivalent of "Hello World", but it is still enjoyable to watch the LED turning on and off after successfully installing a program (sketch) into the Arduino. I've got mine mounted on Vulcan 1 Digital Logic board made in (or at least assembled in) Calgary.
Originally today, I was going to setup the Arduino as a TNC, but I've gone and misplaced my cable....sigh. Hopefully, I've left it at work, or I'm going to be placing another order with Mobilinkd

Raspberry Pi TNC

As if one project isn't enough (Arduino running as a Mobilinkd TNC). I found this link for a TNC for my favorite platform, Raspberry Pi. (TNC-Pi)
Here is a pic from their website:

I've got a couple on order and will be playing with both the Arduino / Mobilinkd TNC as well as the RaspiTNC.

Mobilinkd TNC

Well, I'm really enjoying my Mobilinkd Bluetooth TNC piggybacked onto my VX-6 (got the idea from VE6AB, Jerry Clement).

The photo does not include the cable running from the TNC to the radio because I'm playing with another project that Rob Riggs of Mobilinkd has shared with everyone. Using an Ardiuno as a TNC

I was able to successfully download his .hex file into my Arduino Nano and now I'm in the process of wiring it up!

Solar Charge Controller & Battery Bank

The 2 solar panels that are mounted on my deck are wired into the charge controller in my garage:

This in turn is wired into my battery bank(s). I have 4 sets of 2 x 12V batteries that I can use at any time. In addition, they all have 50A Anderson Power Pole connectors to plug into my Go Power 1500W Pure Sine Wave Inverter (yellow box under the charge controllers).

If I lose power at the house & garage, this inverter and associated batteries will run my Radiant Tube heater to keep my garage warm. If it is the middle of winter, I have a 3000W Guardian Generator in the shed that I can bring into the garage to warm up and then run outside to power my furnace & refrigerator in the house.

Solar Panels mounted on the Deck

Another of my hobbies that aligns with Amateur Radio is Solar Power. I just installed 2 x Sharp NE-80EJEA solar panels on the railing of my deck. These complement the 2 that are on the shingles of my garden shed (can't show a pic because the are buried in the 4" on snow that we received last night & today)

Yes, all of those white specs are the snow that is still falling!

These panels have several ratings that are important:
Maximum Power (PMax) = 80.0W
Open-Circuit Voltage (VOC) = 21.6V
Short-Circuit Current (ISC) = 5.15A
Operating Voltage (VPMAX) = 17.3V
Current at VPMAX = 4.63A
Maximum System Voltage = 600V
Maximum Series Fuse = 10A

I've wired the 2 panels in series to deliver 24VDC to my charge controller which is a MorningStar SS-20L-24V

Installing the Kenwood TM-D710G

Well I chose today (Halloween) to install my Kenwood TM-D710G Dual Bank APRS Radio into my vehicle. The weather was nice for the kids out halloween'ing, and comfortable to be working on the vehicle.

I'll include some pics later to show the wiring from my battery, as well as the mounting of the head unit and the transceiver under the seat.

Car Antenna Setup

Well, I tried the TRAM 1181 several weeks ago when I was still using my Yaesu handheld and the coverage was less that that of my Larsen 5/8 wave. So I have stayed with the Larsen:

I drive a Hyundai Accent (Which I will never buy again, I have had the worst service from the Calgary dealer and absolutely no support from Hyundai Canada!!!)

With the new vehicles, the gap between the hood & fender of trunk & fender is very narrow. So I went with a Comet CP-5NMO Trunk Lip Mount which uses 18" of RG-174 at the mount to allow clearance for the cable to enter the vehicle, and then converts back to 17' of RG-58 to reach your radio.

This arrangement is working out well for me.

Looking for a mobile antenna

I'm shopping for a new 2m/70cm mobile antenna, and it looks like the most economical route is a TRAM 1181

Jerry, VE6-AB has had good luck with his, so I'm interested to see how it performs on my mobile.

Been away for awhile...

Well, I've been away from the Amateur Radio world for a number of years, but a couple of factors have "encouraged" me to get re-involved.....

First, I work at SAIT (Southern Alberta Institute of Technology) and they have an Amateur Radio Club. Membership has been dwindling and so I'm one a few hams that still access the shack. Also, CARA (Calgary Amateur Radio Association) has a VHF and UHF Repeater here on campus and so they need access to be able to service their gear.

Secondly, I have a friend who has been involved for may years, Jerry Clement, VE6AB and he has been sharing with me the advances they have made in APRS and other VHF digital technology. So I think it's time for me to check out how I can merge my interest in Amateur Radio with my interest in Raspberry Pi Single Board Computers.

Office Raspberry Pi

Here is a photo of my office Raspberry Pi (normally I've got the meter hooked up to measure the current flow to the Raspi). The power is quite intermittent here in the office, so it's not unusual to corrupt the SD card and right now I've got it in my PC to reflash.

I've learned the hard way to ensure I backup the SD card on a weekly basis.

I'm designing an uninterruptable power supply for my Raspi and will post it once I have it completed.

Jumbled Mess

This jumbled mess is my primary temperature logger (raspi15) with a LAMP stack that logs all of the data to the mysql database. Raspi16 is turned on three times a day to receive backup files & data and then shut down so that if I ever have a power outage, I’m hoping that raspi16 won’t be on and I will be able to use the data to restore my original. So far… So good…..

Garage Raspberry Pi

This pic is of the Raspberry Pi web server in my garage office. In the last year, I have setup a Pi in my garage hooked to 3 Temperature Sensors. One at the ceiling, one at my desk, and one outside. Then I’ve added a Pi in my house to monitor the house temp and one at my office to monitor the temp there as well.
All are running wheezy and a LAMP stack, recording the temps into a mysql database.
All of the data is then consolidated into the Pi in my garage.
The sensors are DS18B20, Dallas One Wire devices and I’m using the python programming as suggested on the www.adafruit.com website. These folks have amazing tutorials and a great selection of parts for Single Board devices (and much more!). I have made purchases from them and highly recommend them.
Another good site to purchase electronics in Canada is canada.newark.com.