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In two separate sessions, in an attempt to determine how to reduce interference from Sutro Tower broadcasts to telephone equipment in a home located near the tower, measurements were made which could be used to calculated power density in that home.
>Measurements were made when the auxiliary antennas (located about 100 ft above ground level) were in use, as well as when the antennas at the top of the tower were in use. The measurements ranged from an ambient level of just below 2.0 volts per meter (V/m) to a high of 15 V/m (in one hot spot) inside the home. A number of typical locations measured between 3 and 5 V/m. The high reading of 15 (or .059 mW/cm2) corresponds to about 30% of the power density allowed under the FCC 96 Guidelines for public exposure of unlimited duration (which is .2 mW/cm2 for Channel 2). With transmissions from the upper antennas only, hot spots and variations existed, but in general the power densities when Sutro Tower was operating on its upper antennas were .002 mW/cm2 to .006 mW/cm2 or around 1% to 3% of the allowable values.
There are homes considerably closer to the tower than this one, as indicated in the EIR.
Use of the auxiliary antennas is limited, but will be required (perhaps for considerable time periods) during the DTV mast construction. In general it is limited to times when workers on the tower itself would otherwise be exposed to power levels above the guidelines for occupational exposure - meaning workday hours.
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