Introduction To Ham Radio (US Edition)

What Is Ham Radio:

The ARRL describes Amateur Radio as follows:
“Amateur Radio (ham radio) is a popular hobby and service that brings people, electronics and communication together. People use ham radio to talk across town, around the world, or even into space, all without the Internet or cell phones. It’s fun, social, educational, and can be a lifeline during times of need.”

You can set up a ham radio station anywhere!

On a beach…
On The Beach

…in your overland rig
In Your Rig

…or at home.
In Your Home

Although Amateur Radio operators get involved for many reasons, they all have in common a basic knowledge of radio technology and operating principles, and pass an examination for the FCC license to operate on radio frequencies known as the “Amateur Bands.” These bands are radio frequencies allocated by the Federal Communications Commission (FCC) for use by ham radio operators.”

What Are The License Classes:

In the United States there are three classes of Amateur Radio Operator Licenses (Ham)

  • Technician Class
  • General Class
  • Extra Class

Each Class license increases your privileges on the air.

Primarily the Technician Class license is for VHF/UHF communications, which work well for regional contacts. VHF (2M) and UHF (70CM) are the two most common forms of mobile ham radio communications equipment. Simplex these operate line of sight, which is to say 5-10 miles over flat level terrain.

The General Class license opens up 90% of the HF bands for you. These bands work for around-the-world communications, even with low power and modest antennas. As an example, while driving on Hwy 71 in Austin, Texas, I was able to carry on a conversation with a HAM outside Moscow, in Russia.

Finally the Extra Class license gives you the last small piece of the pie. Primarily these are edges of the bands which more closely overlap with other nations band allocations opening up more opportunities to talk to HAMs from other countries.

How Can You Get Licensed:

Ham Radio Clubs across the country offer testing sessions every month. The ARRL (Amateur Radio Relay League) provides a tool to help you locate Amateur Radio License Exams in your area. TEST FINDER

Tests cost around $15 to take. If you pass the Technician the testing site will let you take your General test in the same sitting for free. If you pass your General test, they will let you take the Extra for free in the same sitting. So with proper preparation it is possible to go from unlicensed to Extra in one day.

Once you pass a test, your license is good for 10 years, at which point you renew your license for free. You do not need to take any further tests.

Training/Study Materials:

There are books from Gordon West to help you prepare for the tests. I found Gordon West’s teaching style in his AUDIO CD Programs to be very compatible with my learning style.

You can take Practice tests for all three license classes here: QRZ.com (free registration required)
Each requires a score of greater than 70% to pass. If you are regularly scoring around 85% on practice tests, you are ready for the real thing!

FCC Law & VHF Radios (Race Radios)

I would like to thank Crom from Tacomaworld for taking the time to write this post, reproduced here with his permission.

This is just and FYI for those that may not know. And the bottom line first…

You may not use a VHF radio in the United States without a valid FCC-issued license or Amateur radio license. Use of VHF radios in Mexico is allowed during the SCORE Baja race, and subject to local regulations.

Here is an example of VHF itinerant/business band frequencies commonly used in the Baja Races. Operators of the frequencies are licensed. If you transmit on frequencies you’re not licensed for, then you are operating a pirate radio station, and are subject to fines and equipment confiscation. 🙁

I have observed a trend of individuals buying ham radios and modifying them to transmit outside the ham bands. That in of itself is not a problem. But if you key up outside the ham bands–that’s illegal, and you put yourself at risk for fines and confiscation (more on that below). Also problematic is buying business band radios and operating them on frequencies without the requisite license.

Some people think the FCC enforcement is a toothless tiger, and nothing bad will happen to them, and maybe that’s all true. But people should know that there are risks involved. And that’s why I took the time to write this, as to inform people. I don’t care what you do in the desert as long as it doesn’t hurt or interfere with other people.

Also, I think it’s incredibly foolish for people to post in a public forum the date, time, and place of a future meet and the illegal frequency they’ll be communicating on. :laugh:

If you have questions about Race radios, I have found this shop to be very helpful. PCI Race Radios. As it turns out they are the itinerant and properly licensed operator of the Weatherman frequency.

Additionally, if your not a properly licensed amateur operator please stay off the 2M & 70cm ham bands, i.e. 144-148 & 430-450 Mhz. 🙂

Finally, WB4CS a licensed amateur radio operator wrote the FCC asking a question and the answer is relevant to the topic here.

Here is what the FCC wrote:

FCC response per WB4CS said:
As you note, “The rules are clear that in order to use Part 90 or 95 spectrum, the operator must have the correct licensing and certified radios to use those services.” The debate you are referring to, therefore, comes down to “How can we get around the rules?” The answer is, “You can’t.” We will be happy to relieve you of thousands or tens of thousands of dollars and your amateur radio license if you transmit on channels you are not licensed to transmit on.

William

FCC Wireless Telecommunications Bureau

For example:

  1. CB
  2. FRS
  3. Licensed GMRS
  4. MURS
  5. Licensed Amateur radio (HAM).

Ham Radio Gear – Part 2

Here are some example mobile transceiver options. Each of these is a dual band radio (2m and 70cm). Also each of these has a detachable, or detached, control head. I’ll add a note next to each with additional features.

Kenwood, Icom, and Yaesu are regularly referred to as “The Big Three.” They are the ham radio equivalent of Ford, GM, and Chrysler. There are other brands, but if we’re focusing on high quality, reliable equipment, these are the brands that are going to receive all of my attention.

Icom

  • IC-2730a – Dual Receiver / Cross Band Repeater
  • IC-880H – D-Star Digital Mode Ready
  • IC-5100A – Dual Receiver / Cross Band Repeater / APRS capable / D-Star Digital

Kenwood

  • TM-V71A – Dual Receiver / Cross Band Repeater
  • TM-D710GA – Dual Receiver / Cross Band Repeater / APRS capable

Yaesu

  • FT-7900R – Dual Band
  • FT-8800R – Dual Receiver / Cross Band Repeater
  • FTM-100DR – Yaesu Fusion Digital / APRS Capable
  • FTM-400DR – Dual Receiver / Cross Band Repeater / APRS capable / Yaesu Fusion Digital

Digital Modes
On the topic of Digital Modes. There are currently three competing standards. (Think VHS vs Betamax) or for you youngsters (BluRay vs HD DVD)

Yaesu has developed and released a system called Fusion. It’s based on C4FM.
Icom has had a system called D-Star for the last 10 years.
Motorola Has a system referred to as DMR, or MotoTRBO.

If my Crystal Ball is tuned properly, I think Yaesu’s Fusion system is going to end up being the winning technology for most average hams. I make no promises that this is correct. However looking at how unsuccessful Icom has appeared to be with D-Star, I think it’s unlikely they’re going to win the battle.

I think the EMCOM (Emergency Communication) crowd is going to flock to MotoTRBO/DMR. In large part because many of the ARES/RACES Emergency Communications types also work with Police/Fire/Search & Rescue Teams and are carrying Motorola radios already.

I didn’t mention Motorola radios above in my list. Motorola builds some exceptionally high quality equipment. However it’s all designed for use as Business Band Radios. They work fine in the Amateur Radio Service, and it’s legal for a Ham to use them as such. However I think anyone leaning toward a Motorola, is already experienced enough that they’re not looking for any advice from me. 🙂

Ham Radio Gear – Part 1

Mobile Radio Gear: (VHF/UHF only in this segment)
Radios for Overlanding fall into two major categories. Handheld Transceivers (HTs) and Mobile Radios.

Handheld Transceivers are effectively “Walkie Talkies” and can run from as inexpensive as $35 per unit for a Baofeng UV-5R all the way up to several hundred dollars for a top of the line Yaesu/Icom/Kenwood digital HT, like this Yaesu FT2DR. HTs typically offer several power settings, with Low being ~ 0.5W, medium being 1-2W, and high being 5W. At 5W the radios tend to get hot while transmitting a lot, and the batteries don’t last long. (It’s worth noting a CB maxes out at 4W in the United States…)

Mobile Radios come in three major varieties, and then have a host of options. The three major types of mobile VHF/UHF rig are:
Single Band (usually 2M)
Dual Band (usually 2M/70CM)
Dual Band CrossBand Repeater (usually 2M/70CM)
The single band radios are exactly what they sound like. These radios operate within a single band, which usually means 2M, although they don’t have to. These usually, but not always, output between 5w on Low Power and upwards of 75W on High.

A dual band radio is virtually identical to the single band radio, except you can select between two bands. This means if you’re in a small group, and if everyone has dual band, you can select which band you want to use. The 2M band is the most popular band in the world. If you’re looking for a quiet place to talk within your caravan, you might choose as a group to move to 70CM for instance.

Finally we have CrossBand Repeaters. These are also dual band radios, but they have two receivers in them, rather than one. This means they act in many ways as if you have TWO radios at the same time in your vehicle. These include a special mode of operation though, that allow you to “connect” the 2M radio to the 70CM radio. Thus, anything received on the 70CM side will be instantly re-transmitted on the 2M side. And anything received on the 2M side, will be re-transmitted on the 70CM side. When coupled with an HT, this can allow you to use the HT on 0.5W on 70cm, but communicate with a remote station using the 50-75W 2M transmitter in your vehicle. (Ask me about “Red River Gorge” in Kentucky sometime.)

Digital Mobile Radios Another newer entry into the Mobile, and HT ham radio market is Digital radios. These all operate normal FM like the others listed, however they include some form of digital encoding. Right now there are no “standards” so each vendor has their own competing protocols. Yaesu appears to have the most widely adopted system with C4FM FDMA and their Fusion Repeaters. This is a fairly in depth discussion on its own, and I’d be happy to field questions to the best of my ability but won’t muddy the waters here.

Like everything else in life, in many ways you do get what you pay for. I personally intend to pick up a few (5?) UV-5R radios to keep in a Pelican case in the truck for dire emergencies but wouldn’t personally trust them as a primary radio. Ham radio is like a lot of hobbies. There are many different ways to participate and enjoy the hobby. I’ve hardly scratched the surface here. I, and I suspect the rest of the Hams on Overland Bound, would be happy to field any discussion on the hobby you might have.

Single Band 2M Radio
Single Band 2M Radio

Dual Band 2M/70CM Radio
Dual Band 2m/70cm Radio

Cross Band Repeater
Cross Band Repeater

Yaesu Digital Cross Band Repeater
Digital Cross Band Repeater

Ham Radio Could Save Your Life

Natural Bridge Kentucky

Natural Bridge

When my wife and I went to Natural Bridge in Kentucky back in 2007 she wrote the following diary note to go with this photo.

While hiking in the park, I noticed that the nearest Cell phone reception was 11 miles down the road from where we were.

There’s also a warning on the bulletin board near virtually every trail head: “Every year, about forty-five people fall from these cliffs. One or two usually result in death. Once contact is made with emergency personnel, it will take at least thirty minutes for someone to arrive. Many falls result in spinal injuries, so the person who comes to find you must wait for the EMTs to arrive to remove you safely – another thirty minute wait. Unpacking all the equipment, bundling you up securely, and getting you back to the emergency vehicle can take over an hour. It’s a forty-five minute drive to the nearest hospital. In other words, if you fall, it could be about three hours before you receive proper medical treatment. And that’s after you actually manage to contact someone.”

I ensured that from my car, parked in the lot I could reach the local 2M repeater in the next town over. I then turned on the cross band repeater, and set the 70CM side of the car, and my HT to match one another. This gave me an instant link to “town” and several times while hiking, I verified that I could both hear the repeater in town, and still communicate with the hams there. (all while using 0.5W) There’s nothing like eliminating the time to get to a place you can call for help.

APRS with an RTL-SDR & Xastir

Special Thanks go out to the authors of the following two blog posts without whom I would have had to have done most of this work by myself:

This post is mostly taking details from the above two sites, and merging them into a single, easy for me to find set of notes on how to get Xastir working with the RTL-SDR on a Debian/Ubuntu based Linux system. This will serve as the foundation of a future version that will be deployed on a Raspberry Pi3-B, configured with a 7″ screen, and installed in my truck for mobile APRS tracking.

Here’s a good screen capture of my Xastir map after running for about an hour.
Xastir Map

Blacklist Drivers:

cat << _EOF_ > /etc/modprobe.d/blacklist-rtlsdr.conf
blacklist dvb_usb_rtl28xxu
blacklist dvb_usb_v2
blacklist rtl_2830
blacklist rtl_2832
blacklist r820t
_EOF_

Install DVB-T dongle:

cd ~/src
sudo apt-get install git build-essential cmake libusb-1.0-0-dev
git clone git://git.osmocom.org/rtl-sdr.git
cd rtl-sdr
mkdir build
cd build
cmake ../ -DDETACH_KERNEL_DRIVER=ON -DEINSTALL_UDEV_RULES=ON
make
sudo make install
sudo ldconfig

Install MultiMon-ng Encoder/Decoder:
While your system is likely to have “multimon” in the software repo, you will need multimon-ng

cd ~/src
sudo apt-get install qt4-qmake libpulse-dev libx11-dev patch pulseaudio
git clone https://github.com/EliasOenal/multimonNG.git
cd multimonNG
mkdir build
cd build
qmake-qt4 ../multimon-ng.pro
make
sudo make install

Install RTL-SDR Kalibrate tool:

cd ~/src
sudo apt-get install libtool autoconf automake libfftw3-dev
git clone https://github.com/asdil12/kalibrate-rtl.git
cd kalibrate-rtl
./bootstrap
./configure
make
sudo make install

Run the Kalibrate tool (Take note of the PPM)
For me Channel 1 was the strongest. (In step 2, use the strongest channel)

kal -s GSM900
kal -c 1

Test APRS Reception:
The PPM value from the above step was about 50, so that’s the value I’m using

rtl_fm -f 144390000 -s 22050 -p 50 -g 42.0 - |multimon-ng -a AFSK1200 -A -t raw -

If everything is working, you should see output similar to the following:

w9zeb@aprsstation:~/$ sudo rtl_fm -f 144390000 -s 22050 -p 50 -g 42.0 - |multimon-ng -a AFSK1200 -A -t raw -
multimon-ng (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
(C) 2012-2014 by Elias Oenal
available demodulators: POCSAG512 POCSAG1200 POCSAG2400 FLEX EAS UFSK1200 CLIPFSK FMSFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA CCIR MORSE_CW DUMPCSV SCOPE
Enabled demodulators: AFSK1200
Found 1 device(s):
0: Generic, RTL2832U, SN: 77771111153705700

Using device 0: Generic RTL2832U
Found Rafael Micro R820T tuner
Tuner gain set to 42.10 dB.
Tuner error set to 50 ppm.
Tuned to 144643575 Hz.
Oversampling input by: 46x.
Oversampling output by: 1x.
Buffer size: 8.08ms
Exact sample rate is: 1014300.020041 Hz
Sampling at 1014300 S/s.
Output at 22050 Hz.
APRS: KF5JZT-2>S0QX8V,K5GJ*,WIDE1*,LAGRNG*,WIDE2*:`}Fl"vR/'"6!}|*A%,'s|!wnz!|3
APRS: W5ROX-3>APOT30,AUSWST*,WIDE1*,WIDE2-1:!3034.44N/09724.99W_009/000g000t079p000h70b10169T2WX
APRS: W5ROX-3>APOT30,AUSWST*,WIDE1*,LAGRNG*,WIDE2*:!3034.44N/09724.99W_009/000g000t079p000h70b10169T2WX
APRS: W5MF-7>S0PQ8Q,N5LUY-2*,LAGRNG*,WIDE2*:'{;il ;[/>"48}146.760MHz T103 -060Marty from Houston=
APRS: W5MF-7>S0PQ8Q,N5LUY-2*,AUSWST*,WIDE2*:'{;il ;[/>"48}146.760MHz T103 -060Marty from Houston=
APRS: NK5P-9>RYUQ2T,WA5GC*,WIDE1*,AUSWST*,WIDE2*:`~&xp!,k/`"6v}147.220MHz_%
APRS: KG5DWX-13>APN391,AUSWST*,WIDE2-1:@271617z3025.30N/09740.88W_000/000g000t084r000p000P000h76b10164.DsVP
APRS: KG5DWX-13>APN391,AUSWST*,LAGRNG*,WIDE2*:@271617z3025.30N/09740.88W_000/000g000t084r000p000P000h76b10164.DsVP
APRS: W5OEM-9>APRS,AUSWST*,WIDE1*:> Ver. 02SEP2006 - TCARES ARCHES System Online: www.tcares.org
APRS: KF5DMO>APTT4,AUSWST*,WIDE1*,WIDE2-1:>/TinyTrak4 Alpha

In order to feed the output from multimon-ng into xastir, you will also need the socat command:

sudo apt-get install socat

Now we’re ready to fire up the RTL-SDR, with multimon-ng. We will redirect the output to the network on localhost:14580
Which is where we’ll then point xastir to look for it’s data.

w9zeb@aprsstation:~/$ sudo rtl_fm -f 144390000 -s 22050 -p 50 -g 42.0 - |multimon-ng -a AFSK1200 -A -t raw - | sed -u -r 's/.{6}//' | socat STDIN TCP-LISTEN:14580,reuseaddr,fork

Finally we need to launch xastir, and tell it how to find our APRS data. Launch xastir, and after the intial setup click: Interface –> Interface Control –> Add –> Internet Server Then select “Activate on Startup”
Deselect “Allow Transmitting (Your RTL-SDR is only a receiver afterall)” Set the host to “Localhost” Then click OK.
Finally you will need to select your new Internet server from the list, and click Start, or just click Start All.

Here’s a “Potato Quality” photo of my Thinkpad X201i running Xastir, with a few stations plotted on the map.

Xastir-Thinkpad

There are several Weather stations in the area I can receive directly as well.
Weather Stations

If everything went well, you should start seeing stations appear on your map. Happy APRSing.

APRS with an RTL-SDR – Part 2

In part 2 of my RTL-SDR powered APRS series I’m going to discuss how I configured an IGate using aprx. The first order of business however is getting the RTL-SDR to receive, and decode APRS traffic. The software I used is called multimonNG the installation of this package is pretty straight forward.

# git clone https://github.com/EliasOenal/multimon-ng.git
# cd multimon-ng
# mkdir build
# cd build
# qmake ../multimon-ng.pro
# make
# sudo make install

Once this is complete, we can fire up rtl_fm which we built in the part 1 and by using the Unix Pipe we are going to send the output of the receiver through multimon-ng and then onto the network. The command I’m using to start the receiver is as follows:

# rtl_fm -g 80 -f 144.390M -s 22050|multimon-ng -t raw -a AFSK1200 -f alpha -A /dev/stdin| netcat -l 6666

This opens the receiver and sets the gain to 80, on the North America APRS calling frequency of 144.390mhz, with a sample rate of 22050hz. The output of the reciever is then sent into multimon-ng which uses the AFSK1200 decoder and the -A flag tells it specifically to use the APRS format. Due to some limitations in how multimon-ng works getting the output into something usable requires interacgint with /dev/stdin. If we ended the command there, the decoded APRS packets would be displayed on the terminal for you like the following entries:

lars@bmc ~ $ rtl_fm -g 80 -f 144.390M -s 22050|multimon-ng -t raw -a AFSK1200 -f alpha -A /dev/stdin
multimon-ng  (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA
             (C) 2012-2014 by Elias Oenal
available demodulators: POCSAG512 POCSAG1200 POCSAG2400Found 1 device(s):
 EAS UFSK1200 CLIPFSK FMSFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA CCIR MORSE_CW DUMPCSV SCOPE
Enabled demodulators: AFSK1200
  0:  Generic, RTL2832U, SN: 77771111153705700

Using device 0: Generic RTL2832U
Found Rafael Micro R820T tuner
Tuner gain set to 49.60 dB.
Tuned to 144643575 Hz.
Oversampling input by: 46x.
Oversampling output by: 1x.
Buffer size: 8.08ms
Exact sample rate is: 1014300.020041 Hz
Sampling at 1014300 S/s.
Output at 22050 Hz.
APRS: W2MN-9>S0RY7V,W5OEM-12*,WD5IYT-2*,WIDE2-1:`}Nbl7'v/"77}
APRS: WD5IYT-2>APNU19:!3019.41NS09748.12W#PHG9550 APRS DIGI UIDIGI 1.9b3 Austin b1
APRS: KF5DMO>SPQU6V,WD5IYT-2*,WIDE1*,WIDE2-1:`}JWl //"5]}/TinyTrak4 Alpha

The last three lines in the above block are actual APRS packets received by the RTL-SDR, decoded by multimon-ng, and displayed on the terminal. This is fun but ultimately I want to push those messages into the APRS network. For this I need to add an IGate like aprx. Installing aprx is much like everything else we’ve done so far.

# git clone https://github.com/PhirePhly/aprx.git
# cd aprx
# ./configure
# make clean
# make
# sudo make install

Next we need to configure aprx. For this edit /etc/aprx.conf. The file is well commented, and should be pretty straight forward. In my case, I set the following fields:

  • mycall
  • myloc
  • passcode
  • server
  • filter

Then in the section I set aprx up to use a TCP socket.

<interface>
tcp-device      localhost 6666 TNC2
</interface>

From this point we need to adjust the line we used to start the receiver, as aprx is listening to a network socket, and not looking at a terminal for packets. So we go back to our initial command and pipe the output from /dev/stdin into netcat and are left with the following:

# rtl_fm -g 80 -f 144.390M -s 22050|multimon-ng -t raw -a AFSK1200 -f alpha -A /dev/stdin| netcat -l 6666

Finally we start aprx

# aprx

And if we want to see the packets as they come in we can tail the aprx-rf.log

lars@bmc ~ $ tail -f /var/log/aprx/aprx-rf.log
2014-12-11 03:59:48.152 APRSIS    R W5ROX-3>APOT30,WIDE1-1,WIDE2-1,qAR,W5ROX:!3034.44N/09724.99W_081/001g002t060p000h78b10196T2WX
2014-12-11 04:00:04.576 APRSIS    R KF5RLL-2>APRX28,TCPIP*,qAC,T2TAS:!3032.53N/09735.37WxPHG0000 Hutto,TX - TX/RX-IGate - Linux/Aprx-2.08 - Uptime 108(hrs)
2014-12-11 04:00:05.848 APRSIS    R kc5wxt>APRS,TCPIP*,qAC,THIRD:@110400z3006.00N/09718.00W_163/001g006t061r000P002h87b10202
2014-12-11 04:00:20.635 APRSIS    R KC5AFM-1>APZAFM,TCPIP*,qAC,FIRST:!3031.57NI09747.27W#Cedar Park Digi Tx-iGate
2014-12-11 04:00:23.406 APRSIS    R KC5AFM-9>APOTU0,WIDE1-1,WIDE2-1,qAR,AE5UM:!3032.07N/09749.74W>070/029/A=000966 13.6V
2014-12-11 04:00:23.624 APRSIS    R KC5AFM-9>APOTU0,WIDE1-1,WIDE2-1,qAR,KF5RLL-2:!3032.07N/09749.74W>070/029/A=000966 13.6V
2014-12-11 04:00:26.710 APRSIS    R KE5RCS-A>APJI23,TCPIP*,qAC,KE5RCS-AS:!3044.65ND09736.13W&RNG0010 1.2 Voice 1293.2000 -20 MHz
2014-12-11 04:00:26.824 APRSIS    R KE5RCS-C>APJI23,TCPIP*,qAC,KE5RCS-CS:!3044.65ND09736.13W&RNG0035 2m Voice 145.130 -0.600 MHz
2014-12-11 04:00:26.824 APRSIS    R KE5RCS-B>APJI23,TCPIP*,qAC,KE5RCS-BS:!3044.65ND09736.13W&RNG0035 440 Voice 440.575 +5.00 MHz
2014-12-11 04:00:30.812 APRSIS    R WB5FMZ-1>APRS,WIDE2-2,qAR,KC5AFM-1:@000001z3032.06N/09745.43W_110/000g000t056r000P001h93b10212/ 15171,12.1V73F45%,F=0,V053105 LOC

That’s it for now.

73!

APRS with an RTL-SDR – Part1

Recently I purchased a RTL-SDR to play with. These are dirt cheap on Amazon or Ebay usually to the tune of $10 or less shipped to your door. I had a few different ideas of how I would use this, but first on my list was to build an APRS receiver & decoder.

First I had to figure out how to get my RTL-SDR working on Linux. First we need to install a bunch of pre-requisite packages on our Debian/Ubuntu system.

# sudo apt-get install doxygen doxygen-gui doxygen-latex doxygen-dbg doxygen-doc gnuradio-dev gnuradio libgnuradio* libboost-all-dev libusb-1.0-0-dev libusb-1.0-0 gnuradio build-essential cmake mono-complete monodevelop libportaudio2 fftw3-dev

Next we need to download and install the rtl-sdr drivers. Please follow This Link for more information.

After installing the drivers, we need to patch gnu-radio. Please follow This Link for more information.

Next we need to blacklist the standard dvb_usb_rtl28xxu kernel module. Run the following command:

# sudo echo "blacklist dvb_usb_rtl28xxu" >> /etc/modprobe.d/blacklist.conf

Next we need to install kalibrate. Kalibrate is a tool used to calibrate the RTL-SDR using GSM towers in the 900mhz band.

# git clone https://github.com/steve-m/kalibrate-rtl cd kalibrate-rtl
# ./bootstrap && CXXFLAGS='-W -Wall -O3'
# ./configure
# make
# sudo make install

Finally, I installed SDR # which isn’t technically necessary for APRS decoding, but it is a fun way to play with the RTL-SDR that doesn’t requiring doing a lot of hacking in Gnu-Radio.

I’m going to wrap up Part 1 here. This should get you to a working state with your RTL-SDR. In Part 2 I’ll go into getting the Ham Radio side of the software configured.

That’s all for now.

73!

APRS – Ham Radio and Mapping

APRS – Ham Radio Special Modes:

One of the great strengths of Amateur Radio is how flexible the hobby is. One type of operation that is very interesting for the Overlander is called APRS. (Amateur Position Reporting System) APRS takes raw NEMA2 data from a GPS, encodes it, and transmits it over the amateur bands. A simple APRS Transmitter/Receiver can be built by connecting an inexpensive handheld transceiver (around $35 on Amazon) to an Android Phone or Tablet with a GPS, and then installing a $4.95 piece of software called APRSdroid. This APRS site can then simultaneously transmit your coordinates, as well as display the near real-time locations of every other APRS station within receiving distance. Imagine a caravan of five vehicles, each with an small APRSdroid powered APRS system in their vehicles, with the map display turned on.

Android Phone, and Baofeng UV-3R
APRS Portable

Map Display
Map Display

Overland Mapping & Ham Radio

It’s no big secret I have a bunch of radios in my truck. In fact one of my next posts will highlight what I have installed in my Mobile Antenna Farm.

Mobile Antenna Farm

One of the radios installed though is a 10w Byonics Microtrak-RTG APRS Transmitter. If you’re not familiar with APRS take a second to read a little about it.

While driving through the mountains on the Rimrocker Trail my APRS transmitter was happily sending out telemetry data every 5 minutes (because I was traveling less than 60 miles per hour) or every time I had a more than a 14 degree change in direction. Because of the range 2m has while in the mountains (Line of sight from 9,000 feet is a long way.) I actually have a pretty complete picture of where we traveled.

RimRocker APRS Tracks

APRS isn’t as perfect as plotting your own maps with an onboard GPS and Tracking software, but it’s kind of neat to know that the family of one of the guys with us could fairly reliably track our progress through the Rocky Mountains.