How to chat with astronauts aboard the ISS: USB dongle and antenna lets Polish man receive images from Russian cosmonauts

• A ham radio operator from Poland has received images from the ISS
• On Reddit he revealed his low-cost method to talk to cosmonauts
• He used a USB dongle known as an RTL-SDR to receive sounds
• When decoded these were revealed to be images of Russian space history
• Amateur radio enthusiasts can regularly talk to ISS crew members

By Jonathan O'Callaghan for MailOnline

Published: 10:54 EST, 4 February 2015 | Updated: 11:18 EST, 4 February 2015

Amateur radio - also called ham radio - operators were dealt a treat this weekend, when Russians aboard the ISS communicated with Earthlings.

And one first-time enthusiast received a welcome surprise when, using a USB dongle and other equipment, he was able to receive the transmissions from the cosmonauts orbiting Earth.

By analysing the bits of data they sent, he was able to piece together images and sounds from the space station that commemorated moments in Russia and the Soviet Union’s space history.

Scroll down for a video of the sounds and to see how the image decoding is done

A ham radio operator from Poland has received images from the ISS. On Reddit he revealed his low-cost method to talk to cosmonauts. He used a USB dongle known as an RTL-SDR to receive sounds. When decoded these were revealed to be images of Russian space history (postcard of Yuri Gagarin shown)

The amazing images were posted to Reddit by 22-year-old student Radoslaw Karwacki, from Poland.

'These images are not transmitted regularly. I was really lucky to receive them, because it was my first experience with this kind of equipment,' he told MailOnline.

'I blindly tuned in on that frequency during ISS flyby and happened to receive the signal.'

Astronauts and cosmonauts on the station regularly communicate with people back on Earth using ham radio.

Indeed, anyone with a radio licence and the right equipment can listen in, or even talk to the astronauts and cosmonauts.

Over the weekend, though, the Russians decided to use a picture transmission method known as slow-scan television (SSTV) to relay images to Earth.

In this instance the images included several of Yuri Gagarin, who became the first human in space on 12 April 1961 - and was born more than 80 years ago on 9 March 1934.

Gagarin is seen in his spacesuit preparing for launch, while the rocket that took him to space - an evolution of which is still in operation today - was also transmitted with the images.

'I think it's a great way to commemorate the first person that went to space,' Mr Karwacki added.

'Having an international crew on the station all the time is something to really think about and appreciate.

'It shows that our civilisation can cooperate to achieve great things, and I'm sure that is something that will grow.

'And it's great that they still remember about their roots.'

By listening to the transmitted sound broadcast on voice frequencies, receivers were able to decode the incoming messages and see the pictures the cosmonauts on the ISS decided to send.

‘Images are transmitted using the Slow Scan Television (SSTV) protocol,’ Mr Karwacki explained on imgur, where he posted the images.

‘Before the picture transmission started, I could hear an astronaut voice - "This is Romeo Sierra Zero India Sierra Sierra" - which is RS0ISS in the Nato phonetic alplabet.

RS0ISS is the Russian callsign from the station, while the Americans used the callsign NA1SS when they communicate with ham operators.

To receive the images and sounds, Mr Karwacki said he used an RTL-SDR USB dongle (shown), an antenna, the SDRSharp programme to receive the data and MMSTV software to decode it

Here is one of the images received by Mr Karwacki. The caption reads: '80 years since the birth of the first cosmonaut of the planet Earth - Y. A. Gagarin'

To receive the images and sounds, Mr Karwacki said he used an RTL-SDR dongle, an antenna, the SDRSharp programme to receive the data and MMSTV software to decode it.

The software is available free online, while such a dongle costs around £10 ($15).

According to the website ISS Fan Club, the transmissions took place on Saturday 31 January and Sunday 1 February.

In total 12 images were sent by the Russian ISS crew.

To make contact, line-of-sight with the station is required, so ham radio operators tune in when the ISS is flying over their location.

ISS crew members often make unscheduled calls back to Earth with ham radios when they have a spare moment.

And by picking up a few bits of equipment you, too, could listen and talk with the astronauts and cosmonauts on the station.

Astronauts and cosmonauts on the International Space Station (pictured) regularly communicate with amateur radio - also known as ham radio - operators back on Earth

Nasa astronaut Doug Wheelock, Expedition 24 flight engineer, is pictured using a ham radio system in the Zvezda Service Module of the International Space Station on 5 September 2010