Sec. 73.154  AM directional antenna partial proof of performance 
          measurements.

    (a) A partial proof of performance consists of at least 10 field 
strength measurements made on each of the radials established in the 
latest complete proof of performance of the directional antenna system.
    (b) The measurements are to be made within 2 to 10 miles (3 to 16 
kilometers) from the center of the antenna array. When a monitoring 
point as designated on the station authorization is on a particular 
radial, one of the radial measurements must be made at that point.
    (c) The results of the measurements are to be analyzed in either of 
two methods. Either the arithmetic average or the logarithmic average of 
the ratios of the field strength at each measurement point along each 
radial to the corresponding field strength in the most recent complete 
proof of performance may be used to establish the inverse distance 
fields. (The logarithmic average for each radial is the antilogarithm of 
the mean of the logarithms of the ratios of field strength

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(new to old) for each measurement location along a given radial).
    (d) The result of the most recent partial proof of performance 
measurements and analysis is to be retained in the station records 
available to the FCC upon request.

[ 50 FR 47054 , Nov. 14, 1985]