SDR – Software Defined Radio

SDR – Software Defined Radio

What is it and why should I carry one? Software defined radio, SDR as its followers call it, is an electronics device that allows you to monitor signals across large swaths of bandwidth using only the SDR software.

So how will this help when the SHTF? Simple, most everyone will have a laptop computer of some sort. It’s beyond this article as to the capabilities a laptop computer will bring to you. That being said you can use this same laptop as a high tech radio receiver!

Here is one of many open source SDR software applications in use. The peaks you see in the uppermost window of the application are actual radio signals. All one needs to do is click their mouse on any of those peaks and the receiver frequency will change.


No knobs, no radio to speak of. Just a USB dongle similar to the one shown below:

Granted the antenna isn’t going to pull in all that much but antennas are something radio survivalists specialize in.

There are many other designs of SDR equipment so it’s suggested you use Bing or Google to search for more information on them. One thing you will learn, these other designs escalate in price as the features go up. There are SDR units that are stand alone and connect via a computer via a USB cable. Some are plug-in units that connect directly to a computer motherboards. Some SDR give you HF access, while the majority are for VHF and higher. Listen in on medical calls, business signals and more.

The list goes on:

Listening to unencrypted Police/Ambulance/Fire/EMS conversations. Decoding unencrypted digital voice transmissions.
Listening to aircraft traffic control conversations. Watching analogue broadcast TV.
Tracking aircraft positions like a radar with ADS-B decoding. Tracking maritime boat positions like a radar with AIS decoding.
Decoding aircraft ACARS short messages. Decoding POCSAG/FLEX pager traffic.
Scanning trunking radio conversations. Scanning for cordless phones and baby monitors.
Tracking and receiving meteorological agency launched weather balloon data.
Tracking your own self launched high altitude balloon for payload recovery.
Receiving wireless temperature sensors and wireless power meter sensors.
Listening to VHF amateur radio.
Decoding ham radio APRS packets.
Sniffing GSM signals.
Using rtl-sdr on your Android device as a portable radio scanner.
Receiving GPS signals and decoding them.
Using rtl-sdr as a spectrum analyzer.
Receiving NOAA weather satellite images.
Listening to satellites and the ISS.
Listening to unencrypted Army communications.
Radio astronomy.
Monitoring meteor scatter.
Listening to FM radio, and decoding RDS information.
Listening to DAB broadcast radio.
Use rtl-sdr as a panadapter for your traditional hardware radio.
Decoding taxi mobile data terminal signals.
Use rtl-sdr as a true random number generator.
Listening to amateur radio hams on SSB with LSB/USB modulation.
Decoding digital amateur radio ham communications such as CW/PSK/RTTY/SSTV.
Receiving HF weatherfax.
Receiving digital radio monodiale shortwave radio (DRM).
Listening to international shortwave radio.
Looking for RADAR signals like over the horizon (OTH) radar, and HAARP signals.