I've been looking into FM transmitters, and I've found one that I think I may use. The transmitter is based off of the KT0803L integrated circuit (http://radio-z.ucoz.lv/kt_0803/KT0803L_V1.3.pdf). The maximum dBµV, as stated in the document, is 113 dBµV, (the minimum is 96 dBµV, typical is 103 dBµV).

(From: https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf02087.html#q4) In Canada, low power FM transmitters that produce a field strength of under 100μV/m @ 30 meters can be operated legally without license, as long as they comply to Broadcasting Equipment Technical Standards 1. I've read some of the specifications of the KT0803L, but I've found no specific dBµV/m listing in the document, nor a transmit power rating in watts. I'm also not quite sure how to calculate these using the information given. I could also modify the antenna, if it means it would comply with the standards.

Is it likely that I would be able to use this transmitter legally, and without a license in Canada? And, if possible to find, what are the field strength levels (preferably in dBµV/m, at a certain distance) that this transmitter produces?

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    $\begingroup$ Welcome to ham.stackexchange.com! We recommend that all new users take the tour to get the most from the site. $\endgroup$ – rclocher3 Jan 22 '17 at 6:13
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    $\begingroup$ An IC like that one has an output power, and that only indirectly matters for regulation – what matters is the observable field strength. Between output power and field strength, the antenna and wave propagation happens! $\endgroup$ – Marcus Müller Jan 22 '17 at 14:14
  • $\begingroup$ Thank you both for your replies. Using the data given, is there a way for me to estimate the maximum field strength that this IC would generate, using a small antenna (possibly something like a small piece of wire)? $\endgroup$ – user136659 Jan 25 '17 at 0:24
  • $\begingroup$ Welcome! Please continue to ask questions. Now to point: One caution: In Canada, as in the USA, the single most important factor is that it not cause interference to any licensed service. So for instance, if you develop a low-power circuit that radiates (intentionally or not) and turn it on in the back of Taxi, and it interferes with their use of radio, then that would be a violation regardless of power level. Spurious signals should always be of concern in this regard, too. They may be unintentional but....(see above) $\endgroup$ – SDsolar Feb 20 '17 at 22:34

Normally only licensed radio-amateurs holding Advanced certifications are allowed to build radio-transmitting apparatus. Please consider getting licensed: http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01862.html

There are amateur radio clubs near where you live that may help with studying for a license as well as with answering some of your questions.

The IC you mentioned has output transmit voltage of about 1V (113dBuV) or 0.02W (20 mW) into a theoretic 50-ohm load.

Under ideal conditions and assuming you are using a simple dipole antenna the field strength using the formula from https://en.wikipedia.org/wiki/Dipole_field_strength_in_free_space is:

E = 7 * SQR(0.02W) / 30m = 0.033 V/m 

or 33000 μV/m @ 30 meters which is way above stated IC limits.

More good reading here: https://www.semtech.com/images/promo/Semtech_ACS_Rad_Pwr_Field_Strength.pdf

Good luck!


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