Broadcast MP3s from Vehicle... - Page 3

pip · 09-07-2004, 02:34 PM

I would have thought that using this was illegal without a licence from the FCC. Any FM transmitter that transmits beyond 100' is illegal without a licence:

"Unlicensed operation on the FM radio broadcast bands is permitted for some extremely low powered devices covered under Part 15 of the FCC's rules. On FM frequencies, these devices are limited to an effective service range of approximately 35 to 100 feet (11 to 30 meters). See 47 CFR (Code of Federal Regulations) Section 15.239. These devices must accept any interference caused by any other operation, which may further limit the effective service range. For more information on Part 15 devices, please see OET Bulletin No. 63 ("Understanding the FCC Regulations for Low-Power, Non-Licensed Transmitters").
[Code of Federal Regulations]
[Title 47, Volume 1, Parts 0 to 19]
[Revised as of October 1, 1996]
From the U.S. Government Printing Office via GPO Access

[CITE: 47CFR15.239]

[Page 675]

TITLE 47--TELECOMMUNICATION

CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION

PART 15--RADIO FREQUENCY DEVICES--Table of Contents

Subpart C--Intentional Radiators

Sec. 15.239 Operation in the band 88-108 MHz.

(a) Emissions from the intentional radiator shall be confined within a band 200 kHz wide centered on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108 MHz.

(b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in Sec. 15.35 for limiting peak emissions apply.

(c) The field strength of any emissions radiated on any frequency outside of the specified 200 kHz band shall not exceed the general radiated emission limits in Sec. 15.209.

(d) A custom built telemetry intentional radiator operating in the frequency band 88-108 MHz and used for experimentation by an educational institute need not be certified provided the device complies with the standards in this part and the educational institution notifies the Engineer in Charge of the local FCC office, in writing, in advance of operation, providing the following information: (1) The dates and places where the device will be operated; (2) The purpose for which the device will be used; (3) A description of the device, including the operating frequency, RF power output, and antenna; and, (4) A statement that the device complies with the technical provisions of this part.

[54 FR 17714, Apr. 25, 1989; 54 FR 32340, Aug. 7, 1989]"

antimatter · 09-07-2004, 03:02 PM

Oh man do i want one

That is tight... the next step would be to get one that worked with the computer and had a slick little application that ran within your chosen front end

Gunmaster · 09-09-2004, 03:22 AM

Quote: Originally Posted by JC-S60

All is relative to the position of both transmitter(s) and receiver.

If the signal of a certain transmitter at the location of the receiver is stronger than another signal, that is going to make the difference.

For example, if you have a 1000 watt station at 100 miles distance and a 10 watt transmitter at 10 meters away, you won't even hear any interference of the 1000 watt station, the 10 watts will blow it all away, for you and your neigbours

What no1knows say goes for AM transmitters only. FM is much more difficult when there are 2 transmitters on the same frequency. As long as there is interference, none of the 2 (or more) stations are going to come through, even if one of them is just transmitting a silent signal.

True to a point. I tried this with 2 meter Fm 140-149mhz. I have a 150 watt amp and every one else is running 35-50 watt mobiles. I was able to key over people sitting under the transmitter keying it up. This repeater is 50 miles from town. Not to mention the other mobiles were alot closer to the repeater then me. I was still able to key over them. Thats why Im sticking with my theory. He who has the most power wins. Its just easy to pick a open frequency and transmit on it.

Avalerion · 09-20-2004, 09:05 PM

We should have a MP3Car radio station... from the cars perhaps.

Joe_Collectible · 09-20-2004, 10:20 PM

My first post. I have been aquainted/friends for ten years with the local owner of radio shack who used to work for the FCC for about ten years. He told me that he used to "triangulate" for the FCC. I am a total newb and this stuff is way over my head, but I wanted to share anyways. Not sure how you triangulate a signal, but he used to bust people that do exactly what your talking about. He made good $$ because he was able to buy into a radio shack franchise. Anyways, he built an amplifier that he calls a lanyard ~Not sure if that is how you spell it or not~ that enables him to Key up on a CB in a truck pretty much over anyone for about 7 states. This is no BS. I sat in his truck and talked to people from Florida and Ohio that were on big arse HAM setups. We live somewhere inbetween

It was only about 5,000 watts if I remember correctly. I didn't realize how awesome it really was until now. We were on a hill about 20 miles from Nashville, TN and could see the city skyline.