Getting Pointing Information from gpredict for use in an External Program

Ham Radio

Special thanks to KN4UU’s post on:

Thought it might be more helpful to go in a bit more detail (also so I won’t forget).

One day, when I get time (yea right) I want to make a custom satellite tracker. The thought is to use inexpensive Raspberry Pi and an Arduino to do the stepper control. I would run gpredict on the Pi, and write a serial string containing the azimuth and elevation data to the Arduino. I would ssh/vnc into the Pi to select the satellite I wanted to point to. The Arduino would have a cheap inclinometer and compass connected and would simply use a control loop to move the device via stepper motors until the the position data matches the target. The first step is to compute the pointing data.

Gpredict does a good job of this. So, we now need to get the pointing data out of gpredict in a fashion we can send to an Arudino. This method basically uses rotctld as a pass-thru and only uses a small fraction of its functionality (not really how it was intended to be used).

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2019-09-03,15 Lowering and Raising the Ham Tower

Ham Radio

I updated my method of raising and lowering my ham radio tower. The tower is about 50 feet tall. I added a Harbor Freight winch which allows me to raise and lower the tower from a safe distance.


Antenna Analyzer Box

Ham Radio, Laser Cutting

Now that I have both a VHF/UHF and now a HF antenna analyzer, I figured it would be a worthy investment to get a decent Harbor Freight “Pelican Case” for them. However, I couldn’t stop there. Figured I’d have some fun with the laser making some labels for the box. I also laser’ed my name and contact info in the paint of the actual analyzers as well.

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Ham Radio

Well, I managed to take a perfectly good $15 dollar APRS I-Gate solution and make it WAY more expensive (see For some reason, I wanted to make something that looked more polished. Not sure I succeeded. The goal was to maximize functionality and minimize cost, while allowing me to be lazy, purchasing easy to manipulate modules. Of course, much more money could be saved with custom board work. But that takes effort and time I don’t have.

I do not mean for this to be a how-to, or step by step instructions.  At best, the hope is to spur ideas for better versions.

You can check on the packets this thing finds first at:  Packets that other I-Gates find first, will be reported on their page, even if I hear them too.

Forgive the mess in my shed.

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Zoom Radar

Ham Radio


MD380 tools

Ham Radio

I have fell in love with Travis Goodspeed’s hacked MD380 firmware after a fellow ham pointed to these guys.  It is certainly worth messing around with if you have a MD380.

The git hub page is here.  At the bottom of the page are installation instructions. It is a real good idea to review this page, and make sure you understand what is going on and you are messing with the correct radio, etc.

The big thing I see is that it allows you to load the entire DMR-MARC into the radio. That way, you see the name and QTH of just about everyone talking.

I also like the microphone bar graph. It gives a decent visual representation of your modulation. Good to find where to hold the radio.

Cosmetically, it makes the radio prettier. Read the rest of this entry »



Ham Radio

Been meaning to write a bit about my APRS setup for a while now. Primarily, as many others have, to demonstrate how inexpensive APRS can be.

Some good discussion on what APRS is can be had here and here.

First, you can see my APRS stats, etc from  Nothing special.

The antenna I use is a Firestik 2MCKB that can be had on for around $30 (this is the most expensive thing that I didn’t have lying around). The antenna tower is comprised of an old sailboat mast and is fed with some RG-11 coax I had laying around. The mast has the ability to tilt down (when hurricanes head our way) by pulling a single bolt, and unwinding the brake winch.  I understand, the best I can hope for is a 1.5 SWR with RG-11, but can’t argue with free. Besides, the F-connectors I’m using are supposed to be waterproof (we’ll see).


The signal then goes to an old Bearcat I have.  The eventual plan is to feed it to a Baofeng, which will allow me to transmit.


The audio output (from headphone out) then goes into a $9 usb sound card, that I got off Amazon.  The sound card is plugged into laptop I got for $11 via surplus auction.  The laptop is running Mint Linux.  I’m using direwolf to decode the APRS packets (you can see some in the terminal emulator) and YAAC for display.  I’m starting to prefer YAAC over xastir as, frankly, it is prettier.   This laptop is running from a bootable USB thumb drive (I was to cheep to buy a hard drive for the laptop).

Care must be used when setting the volume levels from both the scanner and the audio in (mic) levels on the usb sound card.  Quieter is better.



Even though it is a fixed location (I plan to eventually put one of these in the car), I put a eight dollar USB GPS on the machine.  It is running via gpsd.


This is an overview of the process I use to install the required software

sudo apt-get install direwolf
cd ~
#modify this file to suit your installation, it will be in your home directory

#go to
and download
mkdir ~/YAAC
mv ~/Downloads/ ~/YAAC
cd ~/YAAC

sudo apt-get install gpsd

#now, you need to start gpsd, direwolf, and YAAC

gpsd [/dev/PATH_TO_GPS_DEVICE]


java -jar ~/YAAC/YAAC.jar


Lowering the Ham Towers

Ham Radio

Videos of my lowering my two ham radio towers.   The wooden one is around 35-40′.  The metal tower is around 50′ tall.

Not sure any of this is something to be duplicated by others or not. The wooden tower is much too heavy. It’s not just safe, it’s 30% safe.

Took the towers down in prep for Hurricane/TS Hermine.  It shouldn’t be bad enough here to warrant taking them down, but figured it would be good practice.

I replaced the wooden tower above with the mast out of a sailboat.   It is much lighter and feels much more safe.

If anyone tries something similar, don’t blame me if something goes wrong!
73, KM4NRZ (now AC4JG ).