August 16, 2018 at 5:33 am #38966Jeffrey KoppParticipant
The Federal Communications Commission has forced a pirate radio station off the air that had served as far-right conspiracy theorist Alex Jones’ flagship in Austin, Texas.August 16, 2018 at 9:22 am #38967BroadwayParticipant
So I guess pirate stations now have been elevated to be consider flagship stations for certain networks…pirates moving on up!August 16, 2018 at 7:55 pm #38972semoochieParticipant
Did you hear about the pirate bread maker who moved on up to the yeast side? 🙂August 17, 2018 at 1:07 pm #38981
Alex Jones’ “Flagship” station?
“Radio Liberty” had been broadcasting with over 100 Watts for 13 years. Defendants snagged the speeding ticket January 2014. Defendants legal brief and responses are comical. Why the media bureau cops didn’t just take the gear then and there is a mystery to me.
https://www.npr.org/2018/08/16/639239647/u-s-sues-operators-of-radio-station-that-airs-alex-jones-show-saying-it-s-not-liAugust 17, 2018 at 4:44 pm #38987lastdayParticipant
That NPR story is an interesting read.August 18, 2018 at 12:07 am #38989Alfredo_TParticipant
The FCC field agent’s report said that the station’s signal had been measured at 22.691 mV/m at a distance of 643 meters from the antenna. I ran this through an RF calculator ( https://www.compeng.com.au/rf-calculator/ ), assuming an antenna gain of 2.15 dBi. The power that the calculator returns is 4.33 Watts, not 100 Watts.
I realize that this far exceeds Part 15 limits, but I wonder why there is such a discrepancy between the two transmitter powers.August 20, 2018 at 1:38 pm #39004
Examine the photograph in the news article link. Tower structure appears to be a tri-pod sectional lattice with either 8 or 10 foot sections. Height above average terrain (HAAT) of structure appears to be 80 or 88 feet (24.4 to 26.8 meters).
There are two co-axial cables within the structure. One is for the 5/8 lambda 11 meter antenna for citizen band radio. The other is for what appears to be a conical antenna or the shield to hide a single FM antenna. It appears to be at 60 feet (18.3 meters).
FCC does not have a minimum output power limit in “Watts” for legal micro-broadcasting. The Effective Radiated Power (ERP) limit is 250 microVolts at three meters. Transmitter Power Output in Watts (TPO) less cable and connector losses times antenna gain in power decibels equals ERP.
Unfortunately, we do not know the FM antenna dBi gain. I suspect it is much less than the “average’ 2.8 dBi as stated and is, in fact, homemade with a negative “forward” gain.
FCC Media Bureau Enforcement measures “22.691 mV/m at a distance of 643 meters from the antenna”. Why so far away? Because the RF level is the hottest “hot spot” they found. The “at 3 meters” point for an antenna is at the apex or zero degrees. Pythagorean Theorem (A^2 X B^2 = C^2) relates measured reception angle is near 30 degrees. In general, a 45 degree reception angle is half power (-3dB).
TPO less losses is greater than 100 Watts using the FCC linear function calculus this forum is unable to reproduce (or I would). I would go into the engineering argument going on for decades FCC FM power formula is isotropic but the point is moot.
Tower is also moot after the 2018 SWSX mini – antifa riot in the apartment complex parking lot. The big music venue is at the Travis County Fairgrounds near eight miles away. Seems operators never apply for a County permit.
First calculation error may be input data is in milli and not micro (22,681 uV/m^3).
Math is Fun!August 20, 2018 at 3:30 pm #39008Andy BrownParticipant
“Height above average terrain (HAAT) of structure appears to be 80 or 88 feet (24.4 to 26.8 meters).”
You mean height above ground (HAG). You would need the exact coordinates to determine HAAT which can never be estimated by looking at a picture.
“The Effective Radiated Power (ERP) limit is 250 microVolts at three meters.”
You mean the maximum allowable field intensity. ERP is a power and is expressed in watts and indicates the power AT the antenna, not at 3 meters from the antenna.
Single element vertical antenna can have positive gain, like in a 5/8th wave or J-Pole antenna. However, the whole setup is as you suggested a home brew design. However, even if you use the typical average for a single element FM H or CP antenna of -3 dB, the required power to establish the FCC field strength measurements is reduced to about 1.5 watts (using Alfredo’s calculator link).
Frankly, there are too many unknowns to analyze how and by how much the system was exceeding parameters.
Also, zooming the photo does not yield a clear image to support your description. It’s a poorly taken photo that goes double image when you attempt to do just that.
Besides, nobody cares how they achieved their signal, it was unlicensed and their claim of immunity to the Rules is laughable. The better question is the one you raised earlier, WTF took so long.
The Pai FCC is seriously fucked up.August 20, 2018 at 4:30 pm #39009
I should mention frequency is also a calculation factor. In general, for a given RF radiation value the coverage area will decrease at the higher frequency by a 25% factor for each frequency decade. Tangents and Curves It’s another argument we can have with the FCC.
HAAT, not HAGL. That big part of Tejas is FLAT. Check with GLOBE. Both are the same.
Effective Radiated Power is not measured at the ATO but at the apex 3 meters away for a reason. Field strength. How many LPFMs purchase those Spanish chromium steel “circular” polarization pig tails for cheap and have to pump 300 Watts into it to get around anywhere?
The single white vertical monopole AT is for CB. I know. I own and use two. When did anyone see or use one for FM. Vertical polarisation? I don’t think so.
compeng.com.au is like wikipedia. A good place to start but don’t depend on the results on an application. Use the lin calc FCC specifies.August 20, 2018 at 4:59 pm #39010
Okay, I’ll bite.
22.691 mV/m measured near 640 meters away is .186 Watts / m^3 or near 87.12 dBu. With no gain antenna, HAAT, frequency and LOS reception measurement angle, ERP is near 222.1 Watts at 3 meters +/- 27 Watts.
Um … it was Tom Wheeler’s FCC.August 20, 2018 at 8:03 pm #39013lastdayParticipant
Hell, last time Binh Nguyen shut down a Eugene pirate he recruited a couple sheriff deputies to back him up while serving notice of violation. No muss no fuss, gear confiscated, end of pirate.
Shutting down any pirate, even one carrying the insane Alex Jones, should be easy peasy. Just have your papers in order and some beefy armed backup. 🙂August 21, 2018 at 10:10 am #39015Alfredo_TParticipant
The FCC action reports fascinate me because they show that unlicensed FM stations with very low powers can be shut down. All that it takes is somebody who is savvy about how to submit a complaint. In my recollection, the country music pirate in downtown Hillsboro that was shut down a few years ago broadcast with just a few tens of milliwatts of power.
Here are the results of two of the calculator websites for 100 W at 643 meters, assuming a simple dipole antenna and no feedline losses.
Compliance Engineering: https://www.compeng.com.au/rf-calculator/
109 mV/m [Power density is 3.16e-5W/m^3.]
I’d be more inclined to believe that they were using a transmitter in the 5-10 Watt range.August 22, 2018 at 1:44 pm #39049
S(uW/cM^2)=33.40891(adj ERP in Watts)/D[meters]^2/0[angle]
Solve for Watts at 3 meters. Learn it. Live it. Love it. And if yer old school, the FCC Smith Chart works for close approximations.
Why at 3 Meters? In general, 100 mHz is the commercial FM mid – band frequency and distance is one lambda [wave-length] from AT.
We can argue how real world the Regulations numbers are (dipole? BE REAL). They go back to LaPointe and Carr in the early 1950s. IT is what IT is.
Canucks do IT different.August 29, 2018 at 7:20 am #39125BorderblasterParticipant
recruited a couple sheriff deputies
Heard Billy-Boy on 3840 last night asking where’s the U.S. Marshals in all those F¢¢ “pirate” raids?
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