As I’ve said in previous posts, ham radio is an important part of any permaculture design. Not only does it provide for communications resilience in times of emergency, it also makes for a really fun hobby. While the learning curve, licensing requirements and equipment costs can be a hurdle for some, the simple act of listening (AKA ‘monitoring’) is a great way to dip your toes into the world of radio.
Flipping through the January 2013 edition of QST Magazine I read the article ‘Cheap and Easy SDR‘ by Robert Nickels, W9RAN. It describes a very inexpensive way to assemble a 300 KHz to 1700 MHz receiver for your laptop using off-the shelf components that you can buy online. The article is behind a paywall, so I’ll paraphrase the content here and provide added resources and recommendations.
OK, so here’s the super inexpensive way to get into Amateur Radio (and more!) monitoring. We’ve all heard of scanners — those radio receivers that can pick up public service, weather, police/fire/ambulance, marine, aircraft, commercial mobile, amateur radio, citizen’s band, walkie-talkie and even baby monitor transmissions — but up ’til now, such wideband receivers were quite pricy, costing anywhere north of $400. What is a radio newbie (or even a veteran) on a tight budget to do?
Not too long ago (Q1 2012), Linux kernel developer Antti Palosaari discovered that $20 USB dongles used for DVB-T (Digital Video Broadcast – Terrestrial) reception had a really wide-range radio receiver in them, so he teamed up with developers at Osmocom (Open Source Mobile Communications) to build drivers and utilities to couple these dongles with SDR (Software Defined Radio) software commonly used by licensed amateurs to receive radio transmissions of all kinds. The DVB-T dongles have limited reception in the 64-1700 MHz range (which includes the 2 & 1.25 meter and 70, 33, and 23 cm amateur radio bands as well as many others including FM broadcast, marine, public service/emergency, and commercial 2-way services), but with an inexpensive $40 RF upconverter developed by Opendous, reception could be extended all the way down to 300 KHz, allowing for monitoring of AM & shortwave broadcast, maritime distress, Citizens’ Band and the 160 to 6 meter amateur radio frequencies. Wow… a nearly “DC to daylight” receiver for about $60 plus laptop, free software, antennas, feedline coax and connectors. With this system you can pretty much monitor anything: all the ham bands, CB radio, AM & FM broadcast channels, public service/police/fire/emergency, commercial 2-way radio, shortwave, marine, air, MURS, FRS, GMRS, intercom systems, older wireless telephone systems and more. This is really quite a breakthrough!
Here is what you’ll need:
1) Computer with a USB port
2) SDR Software. If you’re using Windows, start here: http://rtlsdr.org/softwarewindows. For those on Linux, see: http://rtlsdr.org/softwarelinux
3) Newsky TV28T DVB-T dongle (w/ R820T tuner): http://www.nooelec.com/store/software-defined-radio/sdr-receivers/tv28tv2.html
5) RF Upconverter board: http://www.nooelec.com/store/software-defined-radio/sdr-accessories/ham-it-up-v1-0-rf-upconverter-for-software-defined-radio.html
6) Antennacraft ST4 ultra-wideband discone antenna for 25-1300 MHz receive: http://is.gd/g5Y2Yo
7) The LNR Precision ‘EF SWL’ antenna for 1-30 MHz receive: http://www.lnrprecision.com/endfedz/
8) Appropriate length of 50-ohm coaxial feedline for antenna connections and any adapters needed to attach the feedline to the antenna jack on the RF upconverter. You’ll also need a jumper to connect the dongle to the upconverter. You can find coax and adapters of all sorts at Ham Radio Outlet, but prices are often cheaper on eBay, so search around.
I’ll be putting my SDR receiver system together soon and will write a follow-up with my experiences. If you decide to set one up for yourself, please be sure to let me know. It’s really amazing how modern technology is making PC-based wideband radio accessible to nearly everyone now!
And here are some resources that you might like to check out along the way:
Open source Software Defined Radio project
SDR dongles, RF Upconverter, and accessories
Info on DVB-T dongles based on the Realtek RTL2832U chip
Trunk tracking for APCO25, EDACS 4800/9600, Motorola, and MPT1327 protocols
HamRadioScience SDR videos: http://www.youtube.com/user/hamradioscience?feature=watch
W9RAN’s SDR Archives: http://tinyurl.com/blsg2or
SDR tutorials, guides and reference material
Monitoring Times magazine: http://www.monitoringtimes.com
Popular communications magazine: http://www.popular-communications.com
The Amateur Radio Relay League
Ham Universe: http://www.hamuniverse.com
Not just for hams, it includes articles, tip and tricks for CB and shortwave listening too!
Shortwave broadcast listening guide, forum and resources
Worldwide Radio Forum: http://www.worldwidedx.com
Discussion forum for all things radio. Have a question? It’s probably already been asked and answered!
Have fun and 73!