Many phones today have FM radios built in. You
may not realise it, but your phone could have an FM radio receiver inside. However manufacturers
don't always include an app to access it. It's kind of odd that a legacy radio format first
popular in the 1980s is still being included in digital devices today. And most of the time
it's not even mentioned. This quirky situation has come about because there are some places in
the world that still rely on FM radio. Such as in developing countries and Qualcomm, who make
many of the chips for smartphones and tablets, include FM radio along with other standard phone
features. Such as Bluetooth Wi-Fi and GPS in their chips. That's because it's easier to make one chip
and let the phone makers decide which functions to include in their phones. So if you want to
find if there's a radio in your phone, there are third-party apps that can activate the radio.
One of the apps that's able to detect if your phone has a radio inside it is called NextRadio.
There was even a version of NextRadio for iPhone that could enable the hidden FM radio. The Federal
Communications Commission in the United States asked Apple to enable access to the
built-in FM radio in iPhones by default. To help with natural disasters and communications.
But Apple has since deleted NextRadio from the app store and removed FM radio functions from their
chips since the iPhone 7. Samsung has been much more open about allowing access to their hidden
radios. In my Windows 11 on Lumia phone video, I was amused that the developers of the Windows
On ARM project for Lumia included an FM radio app for Windows. That prompted me to go looking at
some of the old phones I have. And I found this Samsung Core Prime from 2014. It already has an
FM radio app included. To use the radio function a pair of headphones needs to be plugged in. This
is because the headphones also act as an antenna. At this point after listening to the radio for
a bit, the idea of a radio in your phone becomes kind of boring. But if you've seen my videos
in the past, you may have seen that I like to try interesting experiments. Such as that time I
recorded video onto audio cassettes. Or that time I turned a broken camcorder into a data backup
tape drive. Well something I always wanted to try is sending images over radio. Using a method that
amateur radio enthusiasts have been doing for decades. Called Slow Scan TV or SSTV. I downloaded
an Android app called Robot36 that does SSTV. And I've set up a phone in the background
that's going to send images to this Samsung. So let's have a look at receiving some
images using the built-in FM radio. Then afterwards we'll have a look at the phone
sending the images and see how all this works. This SSTV software is really cool I'm running
the FM radio app in the background. And the Robot36 app listens through the microphone and
decodes the images out of the audio signal. I had to set this up with the FM radio playing
through the headphones and then feed that back into the microphone. While it would be possible
to do this in software entirely inside the phone. Rather than go to the trouble of doing that.
I found the easiest way was to simply get the signal through the headphones and then back in
through the microphone for the SSTV decoder. So that's how I set up the receiving station.
But I also need something to send the images. So I needed to find a phone with a built-in FM
transmitter. These are quite rare. But they were more common in the 2000s. Before most cars came
with built-in Bluetooth, FM radio was an easy way to play music from your phone directly into
your car stereo. Even so finding a phone with an FM transmitter inside is still difficult. Most
manufacturers didn't include FM transmitters because of all sorts of regulations in different
countries around the world. There was an Android phone in 2013 by Fujitsu that had an FM
transmitter. But it was a Japanese release only and really not easy to get. I was having a
look through my junk phone box and I found this Nokia N8. This is Nokia's flagship model from
2010. Launched the same year as the iPhone 4. It's got some interesting features compared to
other phones at the time. Such as a 12 megapixel camera, and it's got HDMI output. But importantly
it's also got that feature that I'm looking for. It has an FM transmitter built in. That means when
I play some music on the Nokia, there is a menu option to switch on the FM transmitter. Turning it
on causes music to start being transmitted on FM radio. Using the frequency that you've chosen.
In this case I've set it to 88.1 megahertz. Which has no radio stations near me. On the
Samsung I've set it to the same frequency, and now we can hear the music
that's playing on the Nokia. I'll do a quick range test. This is not a strong
transmitter. It's only about 10 micro watts. It is static at two meters. Three meters. Until you're done at four meters. So to send the image over FM radio I've had to
upload both a jpeg and an SSTV audio version. The jpeg is just for viewing. The SSTV audio version
is what's required to send the actual image. If I had that Japanese Fujitsu phone I could have done
the conversion on the phone itself. But instead I used some Windows software called MMSSTV to do the
conversion and then upload that into the phone. Then it's just a matter of playing
the converted image as SSTV audio. And this is what the SSTV signal sounds like
when it plays through the FM transmitter. Each warble in the sound is a single line of
video. With both brightness and colour information all encoded in an analogue stream. That signal
then gets decoded by the Robot36 app into Samsung. Achieving my goal of sending images phone to phone
without internet or 4G, no Bluetooth and no Wi-Fi. It's been really interesting
learning about Slow Scan TV. Next time I play Portal 1 and 2 I'm ready to
decode the hidden SSTV images in both games. I really enjoy making these videos and I hope you
enjoy watching them. If you have any thoughts on all this I'd be keen to hear them. Thanks
for watching and I'll see you next time.
