Raspberry Pi Satellite Rotator Interface

MacDoppler and GHTracker

MacDoppler and GHTracker

We’ve been using our Portable Satellite Station 2.0 for some time now, and it works great. One area that can be improved is the interface between the MacDoppler Satellite Tracking program we use and the GHTracker application, which controls the Green Heron Engineering RT-21 Az/El Rotator Controller in our setup. Our initial approach was to run the GHTracker app under Windows/VMWare on the same MacBook Air laptop that runs MacDoppler. While this approach works ok, it was more complex and less reliable than we had hoped.

Fortunately, MacDoppler and GHTracker use a UDP-based interface that will run over an IP network.

GHTracker Running On A Raspberry Pi 3

A Raspberry Pi Satellite Rotator Interface – GHTracker Running On A Raspberry Pi 3

Anita, AB1QB, got great results using a Raspberry Pi 2 with a Touch Screen for her DX Alarm Clock Project, so I decided to do something similar with GHTracker. The new Raspberry Pi 3 Model B boards feature a built-in WiFi networking interface and four USB ports, making the RPi 3 a perfect platform for this project. An email exchange with Jeff at Green Heron Engineering confirmed that GHTracker could run under Linux on the Raspberry Pi (RPi).

We wanted a compact package that did not require anything but a power supply to run the final project. There are many great parts available for building a Raspberry Pi system. Here’s what we used:

The total cost for all of the parts was $120.

The assembly of the case and the hardware was straightforward. The folks at Adafruit provide a pre-built Jesse Linux image for the RPi, including the necessary driver for the Touch Screen Display.

After some configuration work and creating a few shell scripts to make it easy to boot the RPi to an HDMI display or to the Touch Display, we were ready to install the GH Tracker App. We also enabled the VNC Server on the RPi to use a VNC Client application on our MacBook Air instead of directly connecting a display, keyboard, and mouse to the RPi. Finally, we installed Samba on our RPi to allow files to be moved between our other computers and the RPi.

GHTracker Running on the Raspberry Pi

GHTracker Running on the Raspberry Pi

Jeff at Green Heron Engineering provided a copy of GHTracker V1.24 and the necessary serial interface library to enable its use on the RPi. Jeff is planning to make a tar file available with GH Tracker and the library in the near future. We did some configuration work on LXDE (the GUI interface for Linux that runs on the RPi), and it automatically runs GH Tracker whenever the RPi is booted up. We also optimized the GUI for the sole purpose of running GH Tracker on the Touch Screen Display. Finally, we configured the Ethernet and WiFi interfaces on the RPi to work with our home network and LTE Hotspot modem.

RPi GHTracker Test Setup

RPi GHTracker Test Setup

With all the software work done, it was time to test the combination with our Satellite Rotator System. The setup worked on the first try using a WiFi network connection between the MacBook Air Laptop running MacDoppler and the RPi. The USB-based serial ports, which control the Azimuth and Elevation direction of the rotators, worked as soon as they were plugged into the RPi. Also, the touchscreen interface works well with the GH Tracker App making the combination easy to use.

MacDoppler and GHTracker via VNC

MacDoppler and GHTracker via VNC

The VNC Client/Server combination allows us to work with the software on the RPi right from our MacBook Air laptop. It also makes for a nice display for monitoring the GHTracker App’s operation from the Mac.

You can find information about how to build your own Raspberry Pi Satellite Rotator Interface here.

Other articles in the Portable Satellite Station series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Thanks to the help from Jeff at Green Heron Engineering, this project was very easy to do and worked out well. The Raspberry Pi 3 platform is powerful and relatively easy to work with. It makes a great start for many Ham Radio projects. Also, there is a wealth of online documentation, how-to information, and open-source software for the RPi. I hope that some of our readers will give the RPi a try!

Fred, AB1OC

Why Ham Radio?

Scorpion SA-680 Screwdriver Antenna

Fred’s Truck with Antenna

Every so often, I drive Fred’s truck to work and people ask me what that big antenna on the back of the truck is for. I explain to them that it is for Ham Radio.  But the reply is usually, why ham radio – isn’t that outdated technology?  We have cell phones and IM, etc…what do we need Ham Radio for?  So I thought I would put down my thoughts as a relatively new Ham about why I enjoy spending so much of my time with Ham Radio.


Amateur Radio for Public Service

Public Service

The number one reason we still need Ham Radio along with all the other technology we now have is for public service.  When there is a disaster and cell phones, television, etc are all not working, Ham Radio operators provide the critical communication.

Ham Radio operators help locally to keep hospitals and first responders in contact with each other to help those affected by the disaster.

Hams also use our ability to communicate around the world on HF bands to help family members around the world to get in touch with loved ones affected by a disaster.

Ham Radio operators have been on the scene helping in every disaster from the earthquakes in Nepal to the recent flooding in California.


Amateur Radio Cube Satellites

Technology and the Maker Movement

I only became a Ham 5 years ago but many of my fellow Ham Radio operators got their license when they were in their early teens and used what they learned to launch their careers. Many have had very successful careers in STEM fields, all launched by their interest in Ham Radio at a young age.  As technology advances, so does the technology used in our hobby.   We even have a nobel laureate, Joe Taylor K1JT who is a ham. Joe has developed weak signal digital communication modes that let us communicate by bouncing signals off the moon!

As technology has advanced, so has the use of it in Ham Radio.   Most Ham Radio operators have one or more computers in their shack.  Many also have a software designed radio (SDR), where much of the radio functionality is implemented using Software, we use sound cards to run digital modes, which are a lot like texting over the radio, and we use the internet extensively as part of operating.  We can also make contacts through satellites orbiting the earth and even the International Space Station.

Most hams love do-it-yourself technical projects, including building a station, home brewing an antenna, building a radio or other station component.  In my day job, I am a program manager for software development projects, but its been a while since I have built anything. As a Ham I taught myself how to code in Python and about the Raspberry Pi and I built the DX Alarm Clock.


QSL Card from VK6LC in Western Australia

International Camaraderie

One of the coolest things about being an amateur radio operator is that you can communicate with other hams all over the world. Ham Radio is an international community where we all have something in common to talk about – our stations and why we enjoy ham radio.    The QSL card above is from a memorable QSO with Mal, VK6LC, from Western Australia, who was the last contact that I needed for a Worked All Zones award.  I must have talked to him for 1/2 hour about his town in Australia and his pet kangaroos!


Amateur Radio Map of the World

Geography Lesson

I have learned much about geography from being on the air and trying to contact as many countries as I can.  There are 339 DX Entities, which are countries or other geographical entities and I have learned where each one is in order to understand where propagation will allow me make a contact.  I have learned a great deal about world geography. Through exchanging QSL cards often get to see photos from so many areas of the world.


DXCC Challenge Award Plaque

Achievement – DXing and Contesting

DXing and Contesting provide a sense of achievement and exciting opportunity for competition. Many Hams work toward operating awards. You can get an operating award for contacting all 50 states, contacting 100 or more countries, contacting Islands, cities in Japan, countries in Asia, or anything else you can imagine.  Each of these operating awards provides a sense of accomplishment and helps to build skills.  Contesting builds skills through competition among Hams to see who can make the most contacts with the most places in 24 or 48 hours. Contesting also improves our operating skills and teaches us to copy callsigns and additional data accurately.


Teaching a License Class

Teaching Licensing Classes – Passing it On

Recently I have joined a team of club members who teach license classes to others who want to get licensed or upgrade their existing Amateur Radio licenses.  Teaching provides a way to improve my presentation skills and also helps me to really understand the material that we teach about Amateur Radio.  It is always a thrill at the end of the class to see so many people earn their licenses or upgrades.

There are so many interesting aspects of Ham Radio which is what makes is such a great hobby.  Getting your license can open up a world of possibilities.  Upgrading to a new license class provides more opportunities to communicate over longer distances.  Ham Radio clubs, including our local club, the Nashua Area Radio Club,  provide many resources to help you get your first licenseupgrade to a new license class and learn about the many aspects of our hobby.

Anita, AB1QB

The DX Alarm Clock – Part 1 Software

Raspberry Pi based DX Alarm Clock

The Raspberry Pi-based DX Alarm Clock

I have been a Ham for 5 years and my favorite thing to do is chase DX. As a new Ham, it was always a thrill to work a new DXCC, but now that I have over 280 DXCCs and over 1000 band points, it is a little more difficult to find a new one. Add to that the fact that I am trying to get a DXCC in 80m and 160m., which are usually open when I am asleep. I created the DX Alarm Clock as a way to get notified that there is something new on the air when I am not down in the shack.  This article will talk about how I developed the software for the DX Alarm Clock.  Part 2 will talk about building the Raspberry Pi-based Hardware and loading the OS.

The DX Alarm Clock is a Python software program running on a Raspberry Pi that gathers data online about my log and what is on the spotting network and uses that data to alert me when there is a “new one” on the air.

DX Alarm Clock and Raspberry Pi Architecture

DX Alarm Clock Architecture

The ClubLog website provides a light DX Cluster website called DXLite, which has an XML Interface. The DX Alarm Clock uses this interface to get the current spots. The software uses the Developer API from ClubLog to get a JSON matrix of all DXCC entities by band indicating whether I have worked, confirmed, or verified each band-entity. The software loops through all of the spots returned by DXLite and looks each DXCC up in the JSON ClubLog matrix. I also use the QRZ.com XML Interface to get additional information for each callsign that is spotted, like the state.


DXCC Configuration Screen

The DX Alarm Clock uses tkinter/ttk for the GUI.  I used the Notebook widget to create a multi-tab GUI.  There is a tab for configuring filters for DX Entity. The user can choose all New DXCCs, as well as specific bands and nodes to provide alerts for.


WAS Configuration Screen

There is another tab for configuring filters for WAS. ClubLog has no log look-up capability based on US State so the WAS filter lets you create a list of States and associated bands to provide alerts for.


Notification Configuration Screen

The Notification tab allows the configuration of what notifications the user would like to receive. The user can specify a separate email address for New DXCCs, New Band Points, and New US States. This allows alerts to be sent to email accounts or as SMS texts. You can also configure the sounds the DX Alarm Clock itself makes to “wake you up” when that ATNO or new Band Point is spotted.

The DXAlarm clock wakes up every 5 minutes and gets the latest spots from the DXLite Cluster. It checks each spot against the ClubLog log and if there is a match based on the configured filters, it sounds the alert, and then speaks the alarm, giving you the Callsign, DXCC Entity, Band, and Mode.   A simple text-to-speech package called flite (festival-lite) was used to implement the speech on the Raspberry Pi.


Alert Screen

It also puts a message with these details and the Frequency, UTC Date/Time, Spotter, and Comment on the display.


Text Notification to iPhone

Additionally, it sends this information as an email to the configured email address, which results in a text or email.


Apple Watch Alert

I can even get the alert on my Apple Watch.


Filtered Spots Display

Once all spots are processed, it keeps a running list of all spots that resulted in alerts on the main screen. Spots are aged out if they do not recur over time.

Raspberry Pi DX Alarm Clock

DX Alarm Clock Hardware

The DX Alarm Clock just alerted me that ZC4SB is on 20m – that’s an ATNO!  Got to go down to the shack and work him!    Stay tuned for Part 2 of this post on the DXAlarm Clock Raspberry Pi-based hardware and on setting up the Raspberry Pi OS.

Anita, AB1QB

Giving Back To Amateur Radio

Nashua Area Radio Club - 2016 Year In Review

Giving Back to Amateur Radio through the Nashua Area Radio Club

Anita, AB1QB, and I have spent a good deal of time this past year with the Nashua Area Radio Club here in Nashua, NH USA giving back to the Amateur Radio Service. Our work with the Nashua ARC has produced some of the most enjoyable and memorable times of our Amateur Radio experience.

Giving back to Amateur Radio - Teaching Nashua Area Radio Club Hosted License Classes

Teaching Nashua Area Radio Club Hosted License Classes

In particular, our contributions to the work that our club is doing around helping people to earn licenses and introducing young people to the Amateur Radio Service have been most rewarding.

Abby, KC1FFX Operating a GOTA Station During Nashua ARC Youth Day - Givigin Back to Amateur Radio

Abby, KC1FFX Operating our GOTA Station during Nashua ARC Youth Day

We recently produced a 2016 Highlights video about our Club’s activities and the club’s contributions to the Amateur Radio hobby. We thought that some of our readers here might enjoy the video. You can view it on our club’s home page here. We hope that you consider giving back to Amateur Radio by volunteering your time.


Fred, AB1OC

Building An Amplifier

Elecraft KPA500 Amplifier

Elecraft KPA500 Amplifier

I have been planning to add a medium power HF Amplifier to our station for some time now. The plan was to use an amplifier of this type for two purposes –  as an amplifier for Anita’s (AB1QB’s) position at our home station and to have an amplifier that we could take along on DXpeditions and other portable operations. After doing some research, it looked like the Elecraft KPA500 Amplifier would be ideal for this. It is small in size, can operate using either 120 VAC or 240 VAC power and has a quite reasonable weight of 26 lbs.  After dropping some not so subtle hints, I received a KPA500 kit as a holiday gift.

The Elecraft KPA500 is a no-solder kit and requires 4 – 6 hours to assemble. Just for fun, I decided to make a time-lapse video of the assembly, checkout and an initial QSO with our KPA500.

The assembly of the kit was quite straightforward and I was able to complete it in about 5 hours. The amplifier worked fine after assembly. It  performs well on all of the Amateur Bands from 160m – 6m and delivers its rated output of 500 W with 25-35 watts of drive power. The initial QSO in the video was made using our Elecraft KX3 Transceiver which provides a maximum of 12 watts of drive power to the amplifier. As you can see in the video, the KPA500 produces about 200 w output using the KX3. I have also tested the KPA500 with a 100W transceiver and found that it produces the rated output on all of the bands and runs cool and quiet. Testing with my station monitor as well as on-air reports indicate that the KPA500 produces a clean signal.

I know that some of you may be wondering how I made the time-lapse video included in this post. I found a very good how-to webpage that explains how this is done and includes links to some good software choices to perform the various steps in the process. The software and hardware that I used are listed in the credits at the end of the video for those who are interested.

Time Lapse Video Setup

Time Lapse Video Setup

The basic setup requires a digital camera on a tripod that can take a series of still images at regular intervals. My video was created using a Nikon D7000 which took a still frame  every 5 seconds. The video required a total of about 3,900 individual photos to produce a 24 fps video that is about 2:40 minutes long. A combination of Batch Photo Editing (Adobe Lightroom), Time-Lapse Assembly, and Video Editing (Apple iMovie) tools were used to complete the project.

The plan is to couple the KPA500 with Anita’s new Flex-3000 Software Defined Radio (I got a not so subtle hint too). More on the Flex-3000 and its operation with the Elecraft KPA500 will be the topic of a future post.

– Fred (AB1OC)

First Tower Part 17 – Feedline Breakout System

Feedline Breakout System

Feedline Breakout System

Since Anita (AB1QB) and I both want to operate at the same time, we are planning to put two SteppIR DB36 Yagis on our tower. These antennas will be connected to a DX Engineering Stack Matching System so that they can be operated together as a 4 over 4 array. The DXE Stack Match can select either antenna individually and connect it to the feedline associated with the array but it does not provide a breakout of both antennas onto separate feedlines. We designed and built a custom feedline breakout system to enable the simultaneous breakout of both antennas to separate feedlines. This project involved the construction of both a tower-mounted box to house a part of relays and a control box for the shack.

This device is inserted between the Stack Match and the antennas in line with the two phasing lines to each Yagi. It is critical that the breakout device provide identical impedance and phasing effects on both phasing lines if the array is to function correctly. To accomplish this, we selected a pair of Tohtsu Coaxial Relays (Model CX-800N) that have a very low SWR impact in the HF bands. These were installed in an outdoor utility box that we got from DX Engineering. Only one relay is used to break out the lower antenna to a separate feedline as the Stack Match can break out the upper antenna to the main feed line for the array. The reason that two relays are needed is to ensure that the RF performance of both phasing lines to the two antennas is identical.

Coaxial Relay

Coaxial Relay

The relays require a 24V source to energize them. I built a simple control box for the shack to provide the needed control voltage. The controller includes three switches so that it can be used for additional 24V relay applications in the future.

Breakout Control Box

Breakout Control Box

I wanted to be sure that the Breakout System had good isolation characteristics between the two phasing lines so that the device did not allow a transmitter using one antenna to interfere or possibly damage a transceiver using the other antenna. The relays we choose have good isolation characteristics which are a good start. To ensure that we have good isolation at a system level, I used an ArraySolutions Vector Network Analyzer (VNA) 2180 to measure the isolation between the various input and output connections in the Breakout System. The ArraySolutions VNA 2180 uses a PC and software to control a measurement unit that can perform one and two-port SWR, impedance, loss and phase measurements (many other measurements are possible as well). In this case, we are making a port to port loss measurement.

Isolation Measurement Setup

Isolation Measurement Setup using a VNA

The VNA 2180 has a dynamic range of about 100 dB which means that it can measure isolation up to this level. As you can see from the following screenshot taken with the VNA software, the isolation of the Breakout System is very close to the limits that the VNA can measure. The worst-case isolation measurement is about -97 dB on the 6m band. We also use Bandpass Filters when we are both operating and these filters provide an additional 55 dB or more of isolation which means we have a total of about 150 dB of isolation through this path. In the real world, the antennas themselves will likely have much less isolation between them than this so the isolation performance of the Breakout System should be more than adequate.

Isolation Measurement Results

Isolation Measurement Results

We are making good progress towards the planned installation of three of our Yagis on the tower next week. I will provide some additional posts over the next several days covering additional aspects of the preparation for next week.

You can read more about our tower project via the articles which follow:

– Fred, AB1OC

Shack Construction – Part 4/4 (Final Setup Of Equipment)

Printer and Phone

Computers, Printer, Phone, and Antenna Switching

The final step in the construction of our new shack was to outfit it with all of the infrastructure for power, RF switching, computers and install the radios and related support systems. This post will outline what we did in this area. One of the first things we did was to get the LAN in the shack working and set up our computers (two Windows 7 PCs) and a local printer. We also installed stands to suspend two computer monitors by each of our operating positions and keyboard trays to allow our keyboards and mice to be stored under the desk when they were not in use. The monitor stands were a good idea as they allowed us to place our displays just above our radios at eye level – perfect for the computer-aided operating that we often do.

We also installed RF ground blocks by each operating position and terminated the ground connections from outside of our shack on the blocks. The ground blocks act as a convenient single point to connect the grounds for all of the devices in our station.

Ground Block

Ground Block

Desk space is usually at a premium in most shacks, and ours is going to be no exception. To best use the available space, we built dollies to place our 13.8V and 28V DC power supplies from Astron on the floor, along with the main unit for our power amplifier (an Icom PW-1).  The amplifier has a small remote control and meter head that sits on our desktop and takes up almost no space.

Dolly's for Amplifier and Power Supplies

Dolly’s For The Amplifier And Power Supplies

The power supplies are terminated on RIGRunner power distribution panels by each of our operating positions as well as by the construction area. We have 13.8V and 28V DC power distribution blocks installed in these locations so that both voltages are readily available for distribution via Powerpole connections. Some of the 13.8V distribution panels have sensing capability so that when we turn on one accessory at each operating position, the distribution panel powers up all of the 13.8V gear in that location – a nice convenience feature. We also added AC power distribution strips at several locations around our operating desk as well as APC UPS Power Supplies on both computers. With this infrastructure in place, we were ready to move our radios and related equipment into the new shack and set it up.

DC Power Distribution

DC Power Distribution

The next step in the equipment setup was to connect our antennas to the antenna switching consoles that were built as part of our shack. These devices were all grounded to the ground blocks for safety reasons. The switch panels allow us to assign our seven antennas to any of the four radios in the shack. This provides a great deal of flexibility when we are both operating at the same time. With the antenna cabling done, we set up both operating positions. Fred’s position is shown here. You can see the FilterMAX III switchable bandpass filtering systems on the right of Fred’s (AB1OC’s) position, which provides needed isolation when both of us are operating on different bands at the same time.

This is Fred's operating position.

AB1OC Position

Here is Anita’s (AB1QB’s) operating position. Anita has a single radio installed but plans to add a second one soon. She has her own set of bandpass filters on the right of her operating position. The filtering and antenna switching matrix combination allows us to operate our station in a multi-SO2R configuration during contests.

This is Anita's operating position.

AB1QB Position

We also set up all our construction and test equipment in the shack. It is a great convenience to have all of this equipment set up and ready for kit-building, making cables, and general test purposes whenever we need it.

Electronic equipment for equipment construction and test.

Construction Area

We took advantage of the storage space in our shack for all of the odds and ends that are handy to have close at hand. This area also provides a nice spot to display our operating awards.

Storage and display area

Storage Area

Finally, we set up an A-V area with a TV, audio system, and remote control and integrated this equipment into our whole-house A-V network. This allows us to listen to music or watch videos when we are not operating in the shack.

TV and Entertainment Audio Equipment

A-V Area

Here is a picture of our completed shack. We were able to get it into operation in time to use it for the 13 Colonies Special Event in July 2012. This allowed both of us to operate simultaneously as K2K, one of the New Hampshire 13 Colonies Special Event Stations.

Our Shack

We are both really enjoying our new shack, and we find that we are operating much now that our equipment and the associated support system are properly set up. We are now working on a significant expansion of our Antenna Farm with the addition of a tower and several new antennas. We will continue to post as we progress on this next phase of our station construction project.

Are you interested in learning more about our shack design and construction? Here are some links with more information:

– Fred, AB1OC

A Tour Of Our Shack

Our New Shack

I wanted to share a little more about our new shack, which was recently completed. Anita and I each have our own operating positions, which are SO2R capable. Anita’s setup consists of a Yaesu FTdx5000 and has provisions to add a second radio in the future. Fred’s position uses an Icom IC-7800 and an Icom IC-9100. Some of the key specifications and capabilities of our shack include:

  • A manual antenna switching matrix that allows us to connect any one of 6 antennas to our radios
  • W3QN bandpass filters systems for each radio to allow simultaneous operation of multiple transmitters at the same time on different bands
  • microHAM MK2R+ and SignalLink USB sound cards to enable digital mode operation
  • Dedicated displays and keyboards for the FTdx5000 ahttps://www.n1fd.org/2017/04/23/member-spotlight-ab1qb/nd IC-7800 radios to enable better use of their built-in Pan Adapters
  • Icom and Yaesu desk microphones and Heil ProSet headsets with boom microphones
  • Bencher paddle for CW
  • Windows 7 (64-bit) computers with dual monitors for running all manner of HAM software (we mainly use Ham Radio Deluxe at this time – more on software in a future post)
  • An Icom PW-1 Kilowatt Solid State Amplifier

The shack also has 125A of dedicated AC power, 70A of DC power, and its own Heat Pump system for heating and cooling. Our house also has a 20 KW automatic generator system that provides emergency power to the shack.

The following are a few pictures of our shack:

This is Fred's operating position.

AB1OC Position

This is Anita's operating position.

AB1QB Position

Our shack also has a dedicated area for equipment construction and test. It sure is nice to have a place where all of our test equipment, etc. can be left connected and set up for immediate use.

Electronic equipment for equipment construction and test.

Construction Area

Our shack includes areas for storage and an A-V area with a TV and entertainment audio. These are all essential items for a complete HAM-cave.

Storage and display area

Storage Area

TV and Entertainment Audio Equipment

A-V Area

Anita and I were able to use our new shack in its multi-op configuration for the 13 Colonies Special Event on the 4th of July. We were both on the air at the same time as K2K New Hampshire, and this was the first test of our station in a multi-operator configuration. One of us did SSB-phone on one band to avoid audio interference, while the other operated digital modes on a different band. For now, we built a matrix of manual antenna switches, allowing any of our four radios to use any available antennas. In the future, we plan to automate all of this with a microHAM system.

The work to construct our shack took about 8 months and was quite a bit of work. We started with an unfinished area of our basement, and we did the framing, electrical, HVAC, plumbing, drywall, ceiling, floor, and finish work. We had the help of several great contractors along the way. We plan to do a series of posts sometime in the future to explain a little more about what went into the construction of the room and the systems which support it.

[fvplayer id=”3″]

The video playlist above provides a “Virtual Station Tour” of our station.

Are you interested in learning more about our shack design and construction? Here are some links with more information:

– Fred, AB1OC