🚀 go-pugleaf

>>>>Anybody know of any circuits or modules that can transmit NTSC black/white
>>>>put real-time vision on a radio-controlled plane. [orig. poster]
>>>
>>>Before anybody says anything else:  Any tv transmitter that can transmit for
>>>at least 2 miles will require FCC approval. ["Mr. Video"]
>> 
>> ..The FCC has allocated bands in which one does not need a license..
>> The only restriction is the field strength measured at a specified distance
>> from the transmitting antenna. One may use any amount of RF power as long
>
>No, no, no, no. The operation being contemplated by the original poster
>does NOT fall under 47 CFR 15 anyway (part 15 of the FCC Rules and Regs).

I note some discrepancies between the specifications you posted, and the FCC
regulations themselves. In order to not mislead nor misinform anyone, I will
comment on each of the paragraphs in turn where I detect a discrepancy.

>    47CFR15.112(a) - 160 to 190 kHz - one watt input power 
This is actually the *alternative* provision for a device that does not meet
the requirements of "47CFR"15.111. This states quite clearly:
"..emission of RF energy on the fundamental or any harmonic or other spurious
frequency does not exceed the field strength.."
10 kHz to 490 kHz    2400 divided by f(kHz) measured at 300 meters
510 kHz to 1600 kHz   24,000 divided by f(kHz) measured at 30 meters

>    47CFR15.113(a) - 510 to 1600 kHz - 0.1 watt input power
Again, this is the alternative provision for 15.111.

>    47CFR15.114(a) - cordless telephone - 50 mV/m at 3 meters at carrier F
>    47CFR15.115    - device illegal to operate from 26.97 to 27.27 mHz
>                     (operations cease Sept 18, 1983) as 
>    47CFR15.116    - 26.99 to 27.26 - voice and data prohibited (A3,F3,A1)
>                     10 mV/m at 3 meters at carrier F 
15.116 only applies to a non-voice device, so the modulation modes make sense.

>    47CFR15.117    - 49.82 to 49.90 - 10 mV/m at 3 meters at carrier F
>                     Emissions not wider than 20 kHz
This applies only to a marketed device, or is home built in a quantity
greater than 5.

>    47CFR15.119    - Home built device (5 or less)
>                     Not marketed
>                     49.82 to 49.90
>                     (b) "the power input to the device at the batter
>                          or power line terminals shall not exceed 100
>                          milliwatts under any condition of modulation
>    47CFR15.122    - (above 70 mHz) - transmission duration not greater
>                     than one second and silent period of at least 
>                     30 times the transmitting duration. 500 uV/m at 3 m
The field strength given is incorrect. The correct field *strengths* are:
(field strengths are measured at *30* meters)
 70 to 130 MHz     50 microV/m
130 to 174 MHz     50 to 150 microV/m (linear interpolation)
174 to 260 MHz     150 microV/m
260 to 470 MHz     150 to 500 microV/m (linear interpolation)
470 MHz and above  500 microV/m

>     Nevertheless, I would challenge anyone to make a radiofrequency power
>amplifier with 1 kw RF output and sufficiently shield it to limit radiation
>to 50 mV/m at 3 meters.  
>
Since there are legal linear amplifiers in Amateur Radio service with 2kW PEP
in the output stage, I wonder what the limit is for type acceptance? The limit
cannot be much if any higher than the receiver emission limits is my guess.

>     Generally speaking, the FCC frowns big-time on homebuilt devices which
>have a DC input power to the final radiofrequency amplifier of 0.1 watts
>or more.
Amateur Radio operators build transmitters and amplifiers with greater power
all the time... They (mostly all) just make sure that they meet the applicable
provisions before putting the device "on the air". The FCC has no (real)
problem with that kind of device.

>     None of the part 15 frequencies would be suitable for television,
>anyway. [David Anthony]
Since any modulation is permissible above 70 MHz (given the limitations above),
I fail to see how the frequencies are unsuitable. If the power level is what
is unsuitable, and the person has the backing of an organization such as a
University, then the person can apply for a special experimental allocation
under Part 5, instead of operating under Part 15. Also doing without color,
and limiting the resolution of the NTSC video will shrink the bandwidth
requirements considerably.
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