View Single Post
Old Dec 19, 2005, 01:14 PM
Mr.RC-CAM is offline
Find More Posts by Mr.RC-CAM
Registered User
Mr.RC-CAM's Avatar
USA
Joined Oct 2001
5,379 Posts
Sorry, but I am correct. For license free use of FCC Part 15 transmitters, the output must be less than 500mV/meter at 3 meters {non-spread spectrum designs}. This is the practical equiv of less than 1mW being radiated from the antenna. In the typical 2.4Ghz consumer design, about 4mW will be driven into the patch antenna element, and due to feedline losses, the output is usually less than 300mV/meter at 3 meters (well within the spec to avoid violations).

Quote:
Even cordless phones radiate more than 1 mw.
Consumer cordless phones, that are not digital spread spectrum, are under 1mW ERP. That is plenty for 100 meters of reliable range (which is the intent of cordless phone app) using a Rx with good uV sensitivity. Consumer Spread Spectrum designs can utilize up to about 1W of native RF power and a bit more EIRP is allowed (ref Part 15 rule 15.247). But, their Effective Radiated RF power is assumed to be 0W due to the way the FCC allows the mfg to measure such signals.

The 47 CFR Part 15 regs are available for download on the FCC's web site. These are the rules that intentional and unintentional radiators of consumer products must follow if used license free in the USA.

EDIT: I forgot to say that regardless of how much or how little the RF power may be, the transmitter cannot be used license free in the USA unless it is FCC registered for such use. That is the purpose of the FCC ID label on compliant consumer device. BTW, our R/C gear falls under the Part 95 rules, which have different rules than the Part 15 devices. Even so, R/C Tx's have FCC ID's on them too.
Mr.RC-CAM is offline Find More Posts by Mr.RC-CAM
Last edited by Mr.RC-CAM; Dec 19, 2005 at 01:27 PM.
Reply With Quote