Tag: RFR

Filing an STA

FCC rules stipulate that when a station is operating at variance from its licensed parameters for more than 10 days, Special Temporary Authority (STA) is required.  The reasons for requesting an STA are varied but could include things like:

  • Damaged transmission equipment
  • Loss of transmitter site or building use
  • Loss of tower
  • Eviction
  • Facilities upgrade or renovation
  • Natural disaster

The loss of the transmission tower at WUPE-FM falls into one of those broad categories.  Thus, we have filed an STA with the FCC for temporary transmission facilities while a new tower is being constructed.  Since the old tower is completely lost, we specified a new tower location, new height above average terrain (HAAT), new ERP, and environmental certification.  To gather that information, several steps were needed:

  • Obtain a new tower location.  This was done with a GPS receiver and verified on itouchmap.com.  Once the NAD83 position was obtained, it needed to be converted to NAD27 for the FCC filing.  The FCC has a conversion tool on its website.
  • HAAT calculation is fairly simple, use the HAAT calculator tool on the FCC website.  For this, the antenna radiation center height Above Mean Sea Level (AMSL) is needed.  Using a topographical map, find the ground level AMSL, convert it to meters, then add the radiation center height above ground level (AGL).
  • The Effective Radiated Power (ERP) calculation is also simple; Transmitter Power Output (TPO) minus system losses (transmission line and antenna gain). It is easiest to do this in dBm, e.g. convert the TPO from Watts to dBm, then add or subtract the gain or losses in dB, and convert the final product back to Watts.
  • The environmental statement is slightly more tricky.  Basically, the filer is certifying that the STA complies with all environmental regulations including OET-65 (RF exposure limits).  Since the temporary antenna is significantly lower than the original, some investigation is required.  For this, there are two methods to demonstrate compliance; ground measurements with a NARDA meter, or RFR worksheets which are a part of the broadcast station renewal form, FCC-303s.

I have taken the RF worksheet sections out of the 303s and separated them into the FM RF Worksheet and the AM RF Worksheet.  These worksheets are not effective for large tower farm-type sites where there are too many variables and RF contributors to be accounted for.  The calculations on the worksheets are not conclusive, however, if the facility in question falls under the limits, it is generally accepted as being in compliance.   Taking ground measurements with a NARDA meter is the definitive method for determining RFR compliance.  Since this is a relatively simple site, the worksheet calculations should be sufficient.

The worksheet calculations show that the RFR is within both the controlled occupation limits and the uncontrolled general population limits.

WUPE-FM temporary antenna RFR worksheet
WUPE-FM temporary antenna RFR worksheet

The position of the new temporary pole was verified on itouchmap.com:

itouch_nadams

It is never good to be operating at a varience from licensed parameters without notification of the FCC. Such things could lead to fine or other problems for the broadcaster.

RF is killing bees!

I found this article and video interesting:  Study links bee decline to cell phones.

The article goes on about CCD (Colony Collapse Disorder) where entire bee colonies die off for unknown reasons.  Some speculate that increased use of pesticides might be to blame (which makes perfect sense to me).  Still, others think that cell phone towers are the culprits.  Noting:

“Animals, including insects, use cryptochrome for navigation,” Goldsworthy told CNN.

“They use it to sense the direction of the earth’s magnetic field and their ability to do this is compromised by radiation from [cell] phones and their base stations. So basically bees do not find their way back to the hive.”

One study in India involved attaching a cell phone to the side of a bee hive and powering it on for two fifteen-minute periods each day. These researchers found that the honey production in the hive dropped off and the hive queen’s egg-laying was cut in half.

All of that is indeed interesting, but somehow I think that a lot of information is lacking.  First of all, any first-year physics student can tell you, the RF field around a cellphone antenna decreases logarithmically as a function of distance.  In other words,  for each unit of distance away from the antenna, the power density decreases by 10 times.  Therefore, placing even a mobile phone directly on a bee hive will likely generate much higher RF fields than would otherwise be encountered, unless there was a bee hive in one of the cell tower antennas.

Secondly, there is no mention of power levels, although the frequency appears to be in the 900 MHz range, if this is the study (.pdf) being referred to in the article.

Finally, the compound referred to, as cryptochrome, is also interesting.  Breaking the word down, one finds “Crypto” which means hidden, and “Chrome” which means color.  According to the Wikipedia article, which most often can be believed when it comes to such subjects, it is indeed used by some animals to detect magnetic fields.  However, RF used by cell phones has long been in use by other technologies such as two-way radio, pagers, cordless phones, baby monitors, TV, early radar, and other high-power emitters.  It would be most unusual that RF-induced CCD would just now be showing up.

In short, there is very very thin evidence that cell phones are causing CCD and it is a shame on CNN for propagating such nonsense without doing research.