Tuesday, March 21, 2017

Thanks Philco for Part 15 Broadcasting

Here we look at the original creation of the rules in 1938, which in it's inception was not #15 but #24. The law was created to provide "substantive" rules specifically providing a right for anyone to utilize it's capabilities.

(The dictionary states that Substantive law refers to the body of rules that determine the rights and obligations of individuals and collective bodies.).

The rules itself had been created to allow a open means to broadcast, but within them included the "exception" that it must not exceed certain limits so not to interfere with licensed broadcasters.
So the way I see it, the law was created specifically to allow unlicensed broadcasting but to be maintained in respect to not causing interference to licensed broadcasters.
The primary objective was to permit free unlicensed broadcasting for the public
The only stipulation was to not cause interference to those who are licensed.

Shown here are the Part 24 Rules in it's entirety, extracted from page 2999 of the original 1938 Federal Register or page 85 of the linked document.
After locating this, I set out to locate any related documents which preceded this to determine what arguments had led to these rules being created to begin with.. I haven't found them yet, however I did come across a very interesting QST Amateur Radio magazine article April 1942 (via this reprint at  rfcafe.com) which explains what actually had prompted the rule to be created; below is a brief excerpt which applies directly to the topic at hand.

"...Until 1938, that is. In that year Philco engineers, seeking a remote-control tuning system without the inconvenient multi-wire cables and accompanying complexities, evolved the idea of using an inductively coupled r.f. transformer with its primary and secondary spaced as much as 75 feet. The primary of this transformer was supplied from a small battery-powered oscillator, and the voltage induced in the secondary fed a supplementary amplifier in the b.c. set.

Naturally, because of its resemblance to a conventional transmitter and receiver, questions arose concerning the legality of the device. After considerable debate pro and con and a hearing or two, the FCC finally handed down rules cov­ering the subject. For the record, those rules are reproduced here in their entirety:..."

It then continues from there quoting the Part 24 Rules which is shown above.

So there you have it, evidently we have Philco to thank for setting the ball in motion which ultimately led to the Part 15 broadcasting we have today!

Thanks Philco!


  1. From the text above: "The only stipulation was to not cause interference to those who are licensed."

    There is another stipulation, shown in Sec. 24.02 of the FCC clipping above, which limits the field intensity from these devices (whether or not interference is produced).

  2. Well, I guess you can look at it at that angle.. but that is not actually "another" stipulation, it's part of the same one. .03 clarifies that the utilization of .02 can not cause interference to licensed entities. So the exceptions primary emphasis is that it can not cause interference.

    None of that has really changed. But the point of my post was that in the beginning the rules primary purpose was to uphold the public right to utilize the airwaves as they please as long as the contained exceptions were observed.

    Over time the rules primary objective has shifted to protecting licensed entities and the public right is secondary.

    Although the rules haven't actually changed much, the way they are written have switched the primary objective. It's just interesting to note.


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