1 [[!meta title="Radio"]]
2 # Amateur Radio and Rockets
6 There are at least two strong motivations for putting radios in rockets. The
7 first is to help locate the rocket after flight, either by using radio
8 direction finding techniques, or by having the rocket report its position as
9 determined by on-board GPS over a radio link. The second is to record data
10 about the flight for later analysis in case the rocket itself isn't recovered.
12 One of the main features of [TeleMetrum](../TeleMetrum/) is the fully
13 integrated radio link. The chip at the heart of our designs includes a highly
14 optimized digital radio transceiver at very low power.
18 To legally operate a radio transmitter, we need to understand and adhere
19 to the rules that regulate use of the radio frequency spectrum. In the
20 United States, the rules that matter to us are published by the
21 Federal Communications Commission, or [FCC](http://fcc.gov/). Under various
22 sections of the FCC rules, particularly Part 15, it is possible to design
23 and build radios that can be used
24 without each user needing to hold an FCC license. Complying with those
25 regulations isn't trivial and can get expensive. Fortunately, there is
28 FCC Part 97 and its equivalent in
29 other countries define an "amateur radio" (sometimes called "ham radio")
30 service. Holders of amateur radio licenses can transmit on many different
31 frequency bands in many different operating modes, using equipment that does
32 not have to be specifically certified. This includes permission to operate
33 telemetry links and remote controls such as what we want for our rockets!
35 ## Getting an Amateur Radio License ##
37 To legally operate a [TeleMetrum](../TeleMetrum) system as designed
38 in the USA, you need at least a "Technician Class" amateur radio
39 license. This is the entry level license, and getting one is actually
40 pretty easy. The exam fee is low ($15?), and the license is good for 10
41 years and renewable for life. Anyone who has been through
42 the written test for a Level 2 high power rocketry certification will find
43 taking a ham radio license exam a similar sort of experience. The test is
45 choice with questions taken from a pool that is completely published ahead
46 of time, and there are some great online resources for learning the material
47 and taking practice exams until you're ready to take the real test. This
48 [ARRL page](http://www.arrl.org/FandES/ead/classes.html) is a good place
49 to start. We also have it on good authority that the book and iOS app
50 available from [Ham Radio School.com](http://hamradioschool.com) are pretty
53 ## Operation in Other Countries ##
55 In Australia, we have learned that operation of our products is legal
56 without a license in the range 433.05-434.79 Mhz under the
57 [LIPD](http://www.comlaw.gov.au/Details/F2011C00543) provisions. However,
58 please be mindful of ham radio and other possible licensed users in that
59 band as licensed users have priority.
61 ## Related Equipment ##
63 It's entirely possible to use just a [TeleMetrum](../TeleMetrum/)
64 in a rocket and a [TeleDongle](../TeleDongle/)
65 on the ground with simple wire whip antennas and nothing else. But there are
66 other pieces of amateur radio gear that we think are worth mentioning because
67 we find them useful too.
71 A popular class of commercially available ham radio transceiver is commonly
72 known as an "HT". These are hand-held, cover one or more frequency bands,
73 and usually are meant to operate primarily using narrow-bandwidth FM
74 voice. Various companies make and sell them, and they have multiple
76 launch. Like walkie talkies or FRS radios (but better!), they can be used to
77 talk to others on the flight line, coordinate search activities, and so
78 forth. Choosing a "dual band" or "multi band" model that covers both
80 and "70 centimeter" bands is a good idea, since 2m is a good band for local
81 voice conversations and the audio tones put out by [TeleMetrum](../TeleMetrum)
82 for direction finding are in the 70cm band.
84 Keith and Bdale both currently own and use the
85 [Yaesu VX-7R](http://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID=111&encProdID=8D3254BFC69FB172D78647DC56EFB0E9&DivisionID=65&isArchived=0)
90 Almost any antenna that covers 435 Mhz can be used for receiving signals
91 from [TeleMetrum](../TeleMetrum).
93 The best hand-held commercial directional antennas we've found for radio
94 direction finding rockets are from
95 [Arrow Antennas](http://www.arrowantennas.com/). The 440-3 and 440-5 are
96 both good choices for finding a TeleMetrum-equipped rocket when used with
99 The best home-made directional antennas for this purpose that we're aware of
100 are based on the ["cheap yagi"](http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf)
101 designs by Kent Britain WA5VJB. Bdale makes his using lengths of pine
102 1x2, 1/8 inch brazing rod for the parasitic elements, and work-hardened 12
103 gauge copper wire for the driven element. The longer versions are great
104 for roving in radio contests, and the 6-element 432 Mhz design works fine
105 for chasing [TeleMetrum](../TeleMetrum)-equipped rockets.
107 ### Other Uses for an Amateur Radio License ###
109 The [ARRL](http://www.arrl.org/) web site is full of information about other
110 things that people do with amateur radio.
112 How about a Doppler radar system for tracking rockets at a launch site? Yes,
113 someone has actually done it! See [this page translated from Russian](http://translate.googleusercontent.com/translate_c?hl=en&ie=UTF-8&sl=ru&tl=en&u=http://serge77.rocketworkshop.net/radar/radar.htm&prev=_t&rurl=translate.google.com&twu=1&usg=ALkJrhi33e0TGe5WOcXr1HpoZBgzjDLy7g)
projects / web / altusmetrum / blob