Sec.  2.1511   Measurements of radiated emissions.

   The Commission's Rules require that the peak efficetive radiated power
   (PERP) of a Class A, B or S EPIRB not be less than 75 mW under certain
   specified conditions. The PERP of an EPIRB transmitter is determined by
   comparing its level to a reference PERP generated by a standard quarter-wave
   monopole antenna located on a one wavelength minimum diameter metal ground
   plane. The Rules also require that all spurious and harmonic emissions be
   attenuated by a specified amount with respect to the reference PERP. In
   addition, there is a limit on the PERP of radiated emissions with the switch
   in the test mode. These measurements are to be made in accordance with the
   following procedure.

   (a) General set-up instructions. Measurements of radiated electromagnetic
   emissions (EME) are to be performed on the 30 meter open field test site
   described in  Sec. 2.1503(a) of this part and on one of the pair of frequencies
   listed in  Sec. 2.1507 of this part. A receiver, tuned dipole antennas and a
   calibrated  signal  generator as described in  Sec. 2.1505 of this part are
   required. The EPIRB should be powered by its own internal battery with its
   standard antenna attached and deployed.

   (b) Set-up for radiated EME tests. 

   Step (1) Place a 121.5 MHz quarter-wave vertical antenna element at the
   center of the ground plane and connect the output of the calibrated signal
   generator to the antenna.

   Step  (2) Mount the tuned dipole antenna on the antenna mast, tune the
   elements to 121.5 MHz and connect the antenna to the receiver.

   Step (3) After an appropriate warm up, turn the receiver to the frequency of
   the test unit, set the detector to peak mode and the bandwidth to 100 kHz.

   (Note: It is sometimes helpful to monitor the receiver audio output with a
   speaker. The EPIRB signal may be identified by its distinctive modulation.)

   (c) Radiated EME tests. 

   Fundamental emissions-peak effective radiated power

   Step (1) Turn on the signal generator and adjust the output to 75 mW at
   121.5 MHz.

   Step (2) Vary the antenna height from one to four meters in both vertical
   and horizontal polarization. Record the highest receiver reading in dBm as
   the reference level.

   Step  (3) Disconnect the signal generator and replace the quarter-wave
   vertical element on the ground plane with the EPIRB under test. The EPIRB is
   to be positioned directly on the surface of and in the center of the metal
   ground plane.

   Step (4) Activate the EPIRB.

   Step (5) Vary the receive antenna height from one to four meters in both
   vertical and horizontal polarization. Record the highest receiver reading in
   dBm and the instrument settings, antenna height and direction for maximum
   radiation, antenna polarization and conversion factors, if any, associated
   with that reading.

   Step (6) Repeat Step 5 with the EPIRB switch in the test position. Return
   the switch to the normal operation position.

   Step (7) Rotate the EPIRB 30 degrees and repeat Steps 5 and 6. Repeat this
   step for all successive 30 degrees segments of a full, 360 degree rotation
   of the EPIRB.

   Step (8) Repeat  Sec. 2.1511(b) and Steps 1 through 7 for 243 MHz.

   Step (9) Compute the peak effective radiated power for the maximum level of
   each measured emission using the following formula:
   [MATH:  :MATH]

   where:

   dBm[meas]is the measured receiver reading in dBm, and

   dBm[ref]is the reference receiver reading found in step 2 of  Sec. 2.1511(c).

   Step (10) Record the PERP in mW. The FCC limit for minimum power in the
   normal operation mode (i.e., with the EPIRB switch in the normal operating
   position) is 75 mW. The FCC limit for maximum power in the test mode is
   0.0001 mW.

   Spurious emissions

   Step (11) Reset the signal generator to operate at 121.5 MHz.

   Step (12) For each spurious and harmonic emission to be measured, retune the
   receive antenna to the appropriate frequency and repeat Steps 5 and 7.

   Step (13) Determine the FCC limit on power for spurious emissions on the
   frequency of each measured emission as follows:

   The rules require that spurious emissions be attenuated at least 30 decibels
   below the transmit power level. Therefore, the maximum received power limit
   for a spurious emission can be calculated from the formula:

   dBm[spur]= dBm[meas]+AF[121.5]−AF[spurfreq]−30

   where:

   dBm[meas]= measured receiver reading (Section 2.1511(c), step 5).

   AF[121.5]= tuned dipole antenna factor at 121.5 MHz.

   AF[spurfreq]= tuned dipole antenna factor at spurious freq.

   Step (14) Record in dB below the fundamental emissions the level of all
   spurious and harmonic emissions within 10 dB of the FCC limits.