Thanks for that.

You are right. Broadcasting was the wrong word.

Given your extensive experience, then perhaps you can help clarify something for me: How do you reconcile the experimental license requirement with the FCC part 15 exemption I linked to?

For reference, my background is hardware development and I have done a fair bit of RF but they've all been in ISM band and we never had to get FCC approval until we intended to make/market the product and don't know of anyone who has ever obtained an experimental license, or a license of any kind.

Was this because of the ISM band or are people technically doing it wrong, but getting away with it because the device isn't radiating so high that it actually interferes with a neighbour and leading to an FCC complaint?

Firstly my training is not primarily in USA FCC regulations, so the terminology will vary. However the basic principles still apply, as all of this derives from the international ITU agreements.

The sources you link to refer to radiated emissions from non-transmit devices. All electronic equipment which is marketed requires a whole slew of Compliance testing.

This covers things like standards for connections to Power or Telephone, as well as Radiated and Conducted Emissions and RF Immunity. Various classes of equipment (eg Commercial, Industrial, Military, etc) have different standards to meet.

Part 15 makes some exemptions for low power Domestic devices. But you still require Type Approval even under Type 15, it's just that the requirements are somewhat relaxed.

If you are an approved developer, you are covered for Possession of non-approved equipment during development.

But this has nothing to do with equipment which can transmit. Transmitters require all of the above testing, but also a further round of testing to do with harmonics, stability, bandwidth, power levels, etc.

If you wish to test a non-approved Transmitter you must do so in a professional-grade screened room, or apply for an Experimental License to cover specific Frequencies and Locations.

Years ago an organisation could apply for a blanket Experimental License which basically covered any testing in the organisation. It's main function was to ensure that a nominated individual understood (and was responsible for) all of the relevant regulations. Typically the nominated individual would hold a First Class Broadcast or Marine ticket. More recently these Licenses have been supplanted by limited permits for specific frequencies and locations.

People think that it is fine to transmit on "unused frequencies". The problem is that there are virtually no frequencies which are not allocated to some organisation.

And people often don't realise how an incredibly low power transmission (or harmonic) can block a sensitive Emergency receiver on the other side of town.

I could tell you dozens of stories of clever people who thought they were using "unused" frequencies. Typically they were inadvertently transmitting on the input frequency of an Emergency Repeater and hundreds of users were slowly getting angrier and angrier until the Authorities managed to track them down. When convicted they not only paid large fines, but also the Investigator's costs and the downtime for the company affected.

The reason for the specific permits is that if things do go wrong, the authorities can quickly get in touch and fix the problem.

I wasn't aware that you'd need a license while developing an intentional radiator (what you're calling a Transmitter, I think). I'll have to look into it.

Thank you for that information.