Sec. 2.1503  Test environment.

    (a) Measurement sites. Radiated emission tests for peak effective 
radiated power (PERP), spurious emissions and power in the test mode are 
to be performed on an open field test site as shown in Figure 1. The 
site is to be located on level ground with an obstruction-free, 60 m by 
52 m, elliptical area. The site is to be equipped with an antenna mast 
capable of adjustment from 1 to 4 m. The center of a metal ground plane 
at least one wavelength in diameter at 121.5 MHz (2.47 m) is to be 
located 30 m from the receiving antenna. The ground plane is to have 
provisions for mounting removable quarter-wave verticle elements to 
produce a monopole antenna at both 121.5 and 243 MHz with the VSWR of 
less than 1.5.

    Note: It is desirable that the level of radiated ambient EME at the 
test site be at least 6 dB below the FCC limits applicable to the EPIRB. 
It is, of course, not always possible to meet this condition. If the 
ambient field strength at some frequencies within the specified 
measurement ranges is too high, it is recommended that one or more of 
the following corrective steps be employed:
    (1) Perform measurements in critical frequency bands during hours 
when broadcast and other radio stations are off-the-air and ambients 
from industrial equipment are lower.
    (2) Insofar as is possible, orient the axis of an open area test 
site to discriminate against strong ambient signals.

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    (3) Vary the bandwidth of the measuring instrument to separate 
ambient EME from emissions from the EPIRB.

    (b) Temperature. Except as otherwise noted, the ambient temperature 
during testing is to be within the range of 4 to 35  deg.C (40 to 95 
deg.F).