Supposedly sometime before 1978 we were allowed 100 mW on 88-108 MHz. Everyone I speak to in the industry knows nothing about it. They say it's always been based on Field Strength. I'm looking for the Actual Rule Part and effective date for the Rule. a link to the actual text would be even better. A scan of an old FCC text of this rule part would be good also.
Thanks,
Rev. Robert P. Chrysafis
Sounds like this 100mW rule neve existed for part 15 fm. Looks like they just change one f/s value to the other, not really changing the actual distance that part 15 fm can go. that really puts this 100mw thing on FM to bed once and for all.
Thank You,
Rev. Robert P. Chrysafis
Universal Life Ministries
http://www.ulc.org
Moderator Hunterdonfree
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I found an old copy of the part 15 regs. from 1967. It is a thermofax copy and probably won't scan well, but I may give it a try later.
Highlights are:
The section regulating FM is part 15.212 and it restricts operation in the FM band to "telemetry and wireless microphones".
It restricts operation to devices which have been type approved and use the antenna supplied by the manufacturer.
Under part 15.212 (d), the field strength limitation is 50 uV/m at a distance of 50 feet from the device.
Hope you find this interesting.
Neil
**edit addition**
The reason I had this in my file is that in 1968 I was working as a biomedical engineer in a university based medical center. We had the need to observe real time EKGs from patients from our office/lab area in a separate building about 200 feet from the ICU. To assess the utility of this, I set up a FM band link and we tested it for a while. Under another part of the rules use of a "home made" transmitter was permitted for educational institutions.
Our project did not go further because we found it was not possible to do remote diagnosis based on the EKG because we could not be assured that the lead placement was correct and to do so required visiting the ICU in which case remote diagnosis was moot.
We were interested in this, not because we were lazy, but because our center was a tertiary center serving a multicounty region where cardiology expertise was not available to many clinics. We thought perhaps sending the EKGs over the land line would be helpful, but at the time it was not. I hope this little piece of my history is not too boring.
Oops, by my editing, our posts got a bit out of order.
Just for comparison with the current 250 uV/m at 3 meters, the previous limit, 50 uV/m at 50 feet extrapolates back to 254 uV/m at 3 m so it is essentially the same.
Neil