4 ms·

Even if part of the spectrum is unlicensed, you're still bound by power limits.

• fegu 7y ago
  And duty cycle limits.
• wglb 7y ago
  And lack of interference to other services
  • JeffGruszynski 7y ago
    Nope. If it's an FCC class B, YOU must accept interference from otherwise approved class B compliant devices. Class B is a very low threshold for that. Mostly it's power limits and not much else. Key fobs, if you look at the fine print, are Class B. There are also exemptions for certain experimental or lab devices though you can't break power limits with those as narrowly defined by regulation. But if you happen to have your Class B device too close such a device, that's entirely your problem, the user of the Class B device. This is a common issue with ham radio: they actually are allowed to interfere with Class B but it's a political decision that drives most of ham radio to "play nice". Legally they have seniority when it comes to interference and the law when it comes to Class B devices. Basically you are screwed with Class B in most cases with little legal recourse. And Class B is such a low threshold that 99% of the time such interference is actually due to bad design or use of cheap components in the Class B device itself. In this case, the fobs. Same goes for TVs, broadcast radio receivers, etc. No one has a right to zero interference from other RF sources for the most part! Mostly because it's physically impossible to assure or deliver! There's merely a regulatory threshold for the extremely bad and summarily interfering levels of RF power.
    • wglb 7y ago
      Putting out a square-wave 315mhz signal can be very broad and hit other non-Class B devices. Regardless of class, spurious emissions are not permitted.