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Apr
01

PSK31…A Ham Radio Mode for the Prepper

The March 27th, 2012, episode of “Doomsday Preppers” on the National Geographic Channel featured the “Ark Two” and it’s Ham Radio station. However, the mode they were using was not voice, but a digital mode known as PSK31 aka Phase Shift Keying 31. For all you techie Preppers, this is right up your ally, but let me reassure the rest of you that PSK31 is really very easy to use and understand.

One of the main reasons that PSK31 is such a great Prepper communications mode is because it makes the most efficient use of the transmitter’s power output. The reason for this is really simple. In order to transmit your voice over the radio waves you use about 2400 Hz of bandwidth using a common voice mode known as Single Sideband (SSB). However, in order to transmit a PSK31 signal you use only 31 Hz of bandwidth, which is just a hair over 1% of the bandwidth used for voice communications. That means if you are transmitting PSk31 data at 5 watts (considered very low power in the Ham Radio world) it would be like transmitting voice at 500 watts (considered high end power in the Ham Radio world) because your power output is focused in such a narrow bandwidth. This gives you huge advantages when operating on solar charged batteries or other Prepper power sources as 5 watts draws far less current than 500 watts.

If there were a downside to PSK31 it would be that a computer with a soundcard interfaced to your radio is required to use the digital mode. However, a computer doesn’t have a to be a big power consuming device and an Electromagnetic Pulse (EMP) protected computer would have some other serious benefits for the Prepper. I would highly recommend that the serious Prepper keep a small “netbook” computer inside a steel trash can and load key files, ebooks, etc. onto that laptop. Not only will this “netbook” computer allow you to communicate with the world using your Ham Radio, but it could store a wealth of books and information that you might not otherwise be able to bug out with.

So what is required to use PSK31? There are three basic components to a PSK31 station. First, a Ham Radio and an antenna capable of transmitting and receiving on the 20 meter (14.070 MHz PSK frequency) and or 40 meter band (7.070 MHz PSK frequency) in the High Frequency (HF) bands. An inexpensive HF Ham Radio is the Alinco DX-SR8, which can be purchased for just over $500 or a great Prepper radio, the Yaesu FT-857, which has both HF capabilities for regional and worldwide communications, but also VHF/UHF for local communications via repeaters all in a small package. Second, a computer, as I mentioned above, a “netbook” with Windows XP, Vista, or 7 and the free PSK31 Digipan Software would be a perfect solution. Third, what is known as a “Radio Soundcard Interface” is needed to connect the radio to the computer’s soundcard, such as the SignaLink USB. The computer soundcard does the work of decoding the data’s audio from the radio’s receiver by linking the audio output of the radio to the line in on your computer and creating the data’s audio to be transmitted by linking the audio from the audio output of the computer to the microphone input of the radio.

The following image shows what the Digipan Software looks like decoding some PSK31 on 20 meters using my station (an FT-847 Transceiver using a R7 Vertical Antenna). Notice that there are multiple yellow/red vertical lines in what is called the “waterfall display.” Each of these yellow/red vertical lines represents a text conversation on PSK31. In the upper portion of the screenshot, you will notice a variety of horizontal lines, this is where the computer automatically picks out the different signals and decodes them in realtime.  The box in the upper left represents the data at the point of the purple diamond at the top of the waterfall display. The purple diamond can be moved and represents where in the spectrum you would be transmitting if you were properly licensed and had the appropriate equipment configuration.  Click the image below to enlarge you will notice a QSO (conversation) between a station in the United States and CU3EJ in Portugal.

If you have a shortwave receiver capable of receiving Single Sideband (SSB) on 14.070 MHz or 7.070 MHz then you can easily get started with monitoring PSK31 simply by downloading the free software mentioned above and configuring it to use a built in or external computer microphone rather than a soundcard interface. Configure the software by clicking “Configure,” then “Soundcard” and selecting your microphone as the input device. Now just set your microphone next to your shortwave receiver and you should start to see your waterfall display populate with conversations if any are present. PSK31 has a unique sound, click this link for a PSK31 Audio Sample, so if you can hear it, your computer can too.

The information, concepts, or opinions from CatastropheNetwork.org are intended for informational purposes only and must be evaluated by the reader, in consultation with a professional, to ensure viability for their individual situation.

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