Radio Communications during a disaster


Duration: 6 min

In this short vid, Walter Cronkite waxes lyrical about the usefulness of Ham radio in disaster situation calling it “the best back-up radio communications system in the world”.

This post is inspired by a great talk I heard at the Last HOPE (Hackers on Planet Earth) 2008 Conference. It focused on “off the grid” voice/data communications options, specifically two-way radio as an effective and reliable means of short-range or global communications in the event of network failures, natural disasters, and political/police actions. Given the risk of network failures and disasters in the countries we operate in, I thought it would be worth while to give the topic a mention.

Listen to audio from the session
It starts with a nice bit of crooning from Zero7 🙂

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flashvars:”file=http://www.aidg.org/multimedia/offgrid_voicedata_comm.mp3&autostart=false” };
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Download Off the Grid” Voice/Data Communications Mp3 [16kbps]
Higher quality version and other Last Hope talks

Which of these solutions is best for you depends on how far you want to communicate, whether or not you want to invest in getting licensed, topography of where you are trying to communicate from (i.e. valley vs mountaintop), etc.

Two Way Radio

Table 1. Summary of personal radio communication options in the United States.
Note: The use of radio transmitters is regulated by national laws and international agreements. The licensing & restriction information listed below is for the US only. Also though they may be similar services in other countries, the frequencies allocated to each may vary by country.

Type Power/Range Descr Frequency (MHz) License Req.
MURS
Multi-Use Radio Service
A private, 2-way, short-distance voice or data communications service for personal or business activities of the general public. Data communications are permitted, but the FCC prohibits image transmissions. 2W
Short Range
VHF Spectrum
Citizen Band (CB)
151.820, 151.880
151.940, 154.570
154.600
No
FRS
Family Radio Service
FRS is often used by families (and activists) because of how inexpensive the walkie talkies are. You can pick them up at your local CVS or Walgreens, for example. However communications are not secure, can be monitored, misdirected and jammed. It shares channels 1 to 7 with GMRS (much to the annoyance o some GMRS users).
Similar services in other regions
0.5 W,
1/2-1 mile
Range is dependent on line of sight. Your range can be diminished by the presence of obstructions like buildings, trees, etc. between the sender and receiver. The altitude of the sender or receiver within the terrain also makes the difference.
UHF Spectrum
14 Channels
462.5625, 462.5875
462.6125, 462.6375
462.6625, 462.6875
462.7125 (Shared w/GMRS)

467.5625, 467.5875,
467.6125, 467.6375
467.6625, 467.6875
467.7125 (FRS Only)

No
GMRS
General Mobile Radio Service
5W (channels shared with FRS)
50W others, though 1-5W is more common
2 – 25 miles depending on the radio and terrain
GPRS is a land-mobile radio service available for short-distance two-way communications between an adult individual and his/her family members. A license is required for use, but primary licensee’s privileges are extended to include communications with immediate family members. GMRS allows voice scrambling for a small degree of greater privacy. Popular brand: Trisquare 900mHz DSS

Note: 462.650, 467.650, 462.700 and 467.700 MHz Not permitted near the Canadian border.

UHF Spectrum
15 Channels
462.5625, 462.5875
462.6125, 462.6375
462.6625, 462.6875
462.7125 (Shared w/FRS)

Lower frequency
(repeater output)
462.5500, 462.5750
462.6000, 462.6250
462.6500, 462.6750
462.7000, 462.7250

Upper frequency
(repeater input)
467.5500, 467.5750
467.6000, 467.6250
467.6500, 467.6750
467.7000, 467.7250

Yes
Good 5 yrs
Fee: $85
No exam
Amateur ‘Ham’ Radio Up to 1500W (Technician License), most are 5W
On UHF/VHF frequencies: 15 miles
On HF frequencies: Global (tend to be larger radios)
Aside from using HF, range can be extended using the internet, satellites, and repeaters.
The ‘amateur’ in amateur radio refers to restrictions that activity be for non-commercial purposes and does not reflect the expertise of operators. Messages can be exchanged by voice, teleprinting, telegraphy, fax, and television. HF (short-wave)
27 amateur service bands
Yes
Exam Required
3 classes: Technician,
General, Amateur Extra

Also note: Repeaters allowed on: Ham and GRMS, but not FRS and MURS.

Thanks Skip Arey, bernieS, Redbird & Lintt for the great information.