Category Archives: Amateur Radio

2024 Field Day

Several us here at the makerspace have amateur radio licenses and like to help with that community also. This year at Field Day we did another educational session at the event organized by PCAuxCom, a local amateur radio group.

Chris(N9VFD) shows Zach (KD9HIG) how to transmit a phone SSTV image.

We decided to give a presentation on SSTV and how it can be used with phone or tablet app to send pictures using an amateur radio – no network connection or cell phone coverage needed! We started using SSTV here at the makerspace to see the occasional transmitted pictures from the International Space Station(ISS) when it passes overhead. Later we discovered the cell phone/tablet apps for SSTV reception and transmission – then realized it would be easy to hold a handheld radio up to the device and transmit images that way.

If you’d like to read more, I’ve created a webpage that describes how it works and includes the presentation made that day. We’re also experimenting with an interface to connect a cell phone or tablet directly to an amateur radio, will update the webpage or stop by the makerspace if you’re interested.

Pictures by Radio

An amateur radio mode called Slow Scan TV (SSTV), given the speed of transmission, is really more about sending pictures than sending video. I’m guessing the name came from it’s similarity to how television video used to work.

SSTV picture of Castlemakers received using an app & ham radio.

I’ve used slow scan to receive images transmitted from the International Space Station as it passes overhead, which has been covered in a previous blog posting. At that time we recorded the transmitted ‘image’ using a voice recording app on a cell phone, emailed the image to a computer, and then used MMSTV to turn the recorded sound into an image. A more permanent/perhaps better setup would be using an interfacing cable to connect the radio directly to a PC with sound input.

Several months ago Ian stumbled across a simple phone app that decodes SSTV images, Robot36. It decodes the image directly on your phone, using the cell phone mic as input. After discovering a similar SSTV encoding app, SSTV Encoder, we realized we could send images directly to each other using our handheld amateur radios.

Closeup of our sign at night using a handheld radio to transmit the picture wirelessly.

Of course you should be able to use this setup with walkie talkies, FRS or even GMRS radios. We’ve used it over our local amateur radio repeater for even longer distances, and planning a demo with some of the other local amateur radio operators probably during Field Day in June.

We’ve started a webpage that explains SSTV and some of the software you can use to view it in more detail if you’re interested in trying it/learning more!

Slow Scan TV (SSTV)

International Space Station SSTV image
Image received from ISS on a pass over Castlemakers

SSTV is an amateur radio method of sending images using a transmitter and radio receiver that’s still in use today! The older transmission mode is not used as much as other digital modes, but there have been some software improvements that improve the quality & allow it’s use on devices other than PCs. Plus you can occasionally hear it used with satellites and the International Space Station (ISS)!

There are 2 popular programs used for transmitting and receiving SSTV transmissions using Windows: MMSSTV and YONIQ.
MMSTV is a very popular software program for amateur radio SSTV, but it is a pretty old windows program that hasn’t been updated since 2010. It still works however and what we first used for receiving transmissions from the International Space Station.
YONIQ is an update of the original MMSSTV which includes many improvements and many new features. The program, developed by a group in Spain, is available in both Spanish and English.
For Linux systems you can try QSSTV and for the macOS you can try Multiscan.

SSTV image of Castlemakers entrance
Cellphone image transmitted using SSTV & handheld radio

More recently we’ve been using our cell phones to decode/code SSTV images. If you’d like to experiment with that, so far we’ve tried Robot36 for decoding and SSTV Encoder for coding an image from an Android phone. Both are pretty simple applications, but seem to get the job done and convenient to use from your cell phone. For an iOS phone you can try SSTV Pad. There are a lot of other programs out there, this is far from an exhaustive list.

For ARRL’s Field Day we did a presentation for a local amateur radio group, you can view that presentation here. We’ve also got a blog post on our website that describes some of our experimentation.

Last updated on 6/23/24.

Satellite Tracker

This began as part of our amateur radio quest to contact someone using the International Space Station (ISS) repeater. You can read more here about listening and contacting other amateur radio operators and the ISS astronauts with an amateur radio license.

Assembled Satellite Tracker (v1)

Here’s a link to the satellite tracker being used in front of the makerspace.

And everything on this page is still a work in progress! Please keep checking back…

Last updated on 1/30/24.

Following Satellites

Last Saturday was Field Day for North American amateur radio, an annual ‘open house’ where 40k ham radio operators get out the radio equipment to make contacts and demonstrate to others how it’s done. We’ve helped out the local group PCAUXCOM the last few years by having a project to build or putting on an education session at their location.

Amateur Radio Satellite Tracker
This satellite tracker was built with 3D printed parts and components from Castlemakers.

Last year we did something on using WSPR with a Raspberry Pi, so for this year we talked about listening to amateur radio satellites and the International Space Station(ISS). Although we don’t currently have the equipment to transmit to a satellite, it’s not hard to listen with a handheld receiver or police scanner. We have hopes of someday acquiring the necessary equipment to be able to actually contact other amateur radio operators using one of the satellites, or one of the radios on the ISS.

We also showed off a prototype satellite tracker that Ian has been designing that was made with 3D printed parts from the makerspace. While it’s still a work-in-progress, the prototype uses data from a satellite tracking app to move a mounted antenna to follow the satellite as it passes the sky overhead. There wasn’t an ISS pass but Ian was able to show how it tracked another satellite during the presentation. The major components were designed in Tinkercad, the same program we use in our Intro to 3D Printing class, and the tracking hardware is moved by software running on a Pi Pico!

ISS & Satellite Listening

The first amateur radio satellite goes back to OSCAR 1 ( Orbiting Satellite Carrying Amateur Radio) in 1961, just 4 years after Sputnik 1. Since then 30 countries have launched amateur radio satellites and AMSAT has designated the latest Hungarian satellite OSCAR 110. Their resource for current operating amateur satellites is on this webpage.

NASA has had a long history of supporting amateur radio, there was even a handheld radio used on Space Shuttle Columbia in 11/1983 on STS-9. So it’s not surprising that a 15 nation consortium formed the Amateur Radio on the International Space Station (ARISS) in 1996.

There are also a number of non-amateur radio satellites, many of these are not easy or ‘open’ as the ARISS and amateur satellites to pickup or listen to.

How can I listen in to the ISS?

Perhaps the easiest of the non-stationary orbiting objects to hear is the ISS when it passes overhead. It is very popular with amateur radio operators because you can occasionally hear an astronaut talking to someone on earth! This is a pretty rare however, although I just listened in 1/30/23 to astronaut Dr. Josh Cassada (KI5CRH) talking to a class in Norwich, Connecticut as it passed over Greencastle.

Most of the ISS voice & data traffic is from earth that is repeated back down, which significantly extends the transmissions and reception using these frequencies. Dedicated equipment is not needed to listen in to the ISS, a handheld police scanner or base unit can do the job.

Here’s some key frequencies to listen in:
145.800 MHz – Voice traffic, this is also the downlink frequency for ARISS classroom contacts. It can also used for SSTV transmissions. Note: the current status here.
145.825 MHz – Data traffic for APRS transmissions. If you can decode it, usually with a PC or Raspberry Pi, the short transmission time makes it easier to verify the contact and usually includes a GPS location for the contact.
437.800 MHz – This is the current downlink frequency that amateur radio operators are using. Listen in to hear efficient communications & contact confirmations, they don’t have much time per pass to talk with other operators!

You can check the current ISS location here; there are also a number of websites, programs and apps that give you more detailed information and predictions of when it will be over your location. It’s also not a bad idea to check on the current status of the ISS onboard radios, which you can do here. The do turn them off during extravehicular activity (EVAs).

There is also a Slow Scan TV (SSTV) radio on the ISS, but it is currently stowed away. We were receiving it last year and special events are sometimes scheduled during the year. We’ve also added a quick reference to SSTV on our website.

Amateur Radio Satellites

While there’s a lot more variation in the amateur radio satellites, most transmit on similar frequencies to the ISS. AMSAT provides a webpage that shows current status of the satellites as reported by others, but it can be a bit overwhelming. But it’s a great place to help make sure the satellites are still operating and some recent report receptions. N2YO also keeps a pretty impressive website that tracks the satellites and allows you to track them at your location also.

Although there’s lots of commercial satellites you can hear, only a few anymore you can still receive and decode the data. One popular series is the NOAA weather satellites – you can view and receive the images directly!

Last updated on 7/14/25.

Listening to the International Space Station

A lot of people don’t realize that Amateur Radio can involve spacecraft, including the International Space Station (ISS). When it passes overhead, there’s a lot more than images you can receive!

When this blog post was written there were 7 astronauts aboard the ISS and several have an amateur radio license. There are 2 radios currently aboard and the astronauts will occasionally use them to contact people when passing overhead, although that is really pretty rare. But the radios are almost always in use, except during a spacewalk, from amateur radio operators sending radio signals up to the station which then repeats them back down to earth.

Set for receiving 2 channels at once, you can hear both voice and data audio from the International Space Station.

The ISS passes overhead an average of 5-6 times a day; anyone can track and predict when it will be passing over their exact location. You can even see the station passing by in the night time sky on a clear night. But what’s exciting to me, as the station passes overhead you can hear amateur radio operators sending voice and data traffic up to the ISS which then transmitted down to earth. That allows their signals to travel much further; I’ve easily picked up signals from Oklahoma and further with a handheld radio or scanner.

A couple of us at the makerspace are working on building an antenna to transmit up to the ISS. If you’re interested in learning more, stop by the makerspace during Open Shop time. And if the ISS is passing overhead, we can let you listen to the traffic yourself!

Radio Beacons

Circuit board & Raspberry Pi used for WSPR transmission.
Raspberry Pi Zero & circuit board Ian built for WSPR

There’s a lot of similarity between amateur radio (or ham radio) and ‘makers’ – in fact many people are involved in both. With the electronics workbench area that we added to the makerspace, there has been even more interest in amateur radio. Several months ago, we put a 2m/70cm member-donated antenna on the roof, then started looking for a transmitter/ receiver & more projects next.

WSPR signal reception graphic.
WSPR Signal reception reports from multiple continents using only 100 mW of power!
Antartica reception report.
Antartica reporting of an Indiana transmission!

A recent article(p30) on building a low power Weak Signal Propagation Reporter (WSPR) radio beacon using an Arduino had us wanting to make one. We have experience with single board computers & most of the parts at the makerspace already – so why not make one! But before I could get mine finished another member, who recently got his amateur radio license, redesigned the project using Raspberry Pi Zero and got his running in Crawfordsville!

Transmitting on less power than many wifi routers (100mW in this case), he’s had confirmation of his signal on the 20m frequency band in Australia, Denmark, off the coast of Africa, and even an Antartica research station! Stop by the makerspace – we’re glad to show off what we’re doing.

Slow Scan TV

This week the International Space Station (ISS) has been broadcasting images using Slow Scan TV (SSTV) from the Russian portion of the station on 145.800 MHz. It’s relatively easy to pick up the signal if you have the right equipment and can calculate the time it passes overhead correctly.

Audio from Tuesday’s ISS SSTV transmission over Greencastle Indiana.
SSTV image received from the International Space Station when passing over Greencastle.

This happens several times a year and will continue through at least June 26th, so we’re going to try receive and decode the image this coming Saturday morning at Open Shop. Overhead passes start 5:10 am, are about 90 minutes apart, and go through 1:22 pm local time. Stop by during our open hours from 9-12 am and you might get to see an image directly from the space station!

Building Antennas

coax cable antenna making
George (KB9RZQ) showing a finished antenna to the group.

For the June Castlemakers Kids meeting we built an emergency radio antenna out of coax cable.  Since it was ARRL’s Field Day, an annual ‘dust off the radios & get on the air’ event, we relocated our meeting to Putnam County’s Emergency Operations Center (EOC), where some local amateur radio operators were seeing how many radio contacts they could make. It also gave everyone a chance to see amateur radio operators making on air radio contacts and then try out the built antennas.

Testing a newly built antenna in the parking lot.
Testing a newly built antenna in the parking lot.

The design uses a short piece of coax cable with a connector on the end, you can see the instruction sheet we made and an example antenna. It’s a simple design that works quite well by cutting a different cable length for different transmission frequencies. Just strip the wire and twist the coax braid then you’re done. The antennas were then hooked up to a radio, and with a licensed radio operator supervision, they tried their antenna, some inside the building and others in the parking lot, to talk to each other.

Of course making antennas and watching radio operators ‘work the grid’ raised lots of questions. Thanks to George Edenfield (KB9RZK) and the rest of the PCAUXComm crew for hosting us. And special thanks to Dave Costin for giving us a behind the scenes tour of the Putnam County EOC – lot going on there many  don’t realize.