Sec. 2.1515  Spectral measurements.

    (a) Set-up. Spectral measurements are to be performed in a shielded 
room.


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    Step (1) Place the EPIRB directly on a metal ground plane, such as 
the shielded room floor. The EPIRB should be powered by its own internal 
battery with its standard antenna attached and deployed.
    Step (2) Place a suitable receiving antenna at a convenient distance 
from the EPIRB and connect it to the input of the spectrum analyzer to 
observe the radiated signal from the EPIRB. A signal generator and 
frequency counter capable of operating at 121.5 and 243 MHz are also 
required for these tests.

    (b) Occupied bandwidth test.

    Step (1) Activate the EPIRB and observe the fundamental frequency on 
a spectrum analyzer. Adjust location of receiving antenna and spectrum 
analyzer controls to obtain a suitable signal level (i.e., a level which 
will not overload the spectrum analyzer, but is far enough above the 
noise floor to allow determination of whether or not the sidebands are 
attenuated by at least the amount required in the rules).
    Step (2) Set spectrum analyzer controls as follows:

I.F. bandwidth: 10 kHz
Video filter: OFF or as wide as possible
Scan time: 100 ms./div.
Amplitude scale: 10 dB/div.
Scan width: 20 Hz/div.
Center frequency: 121.5 MHz

    Step (3) Record the signal level in dbm.
    Step (4) Calculate the mean power reference level by adding 10 
log10 (D), where D is the modulation duty cycle determined in 
section 2.1513(d) of this part, to the recorded signal level.
    Step (5) Set spectrum analyzer controls as follows:

I.F. bandwidth: 100 Hz
Video filter: OFF or as wide as possible
Scan time: 10 sec./div.
Amplitude scale: 10 dB/div.
Scan width: 20 kHz/div.

    Step (6) Check the modulation sidebands for compliance with the 
required attenuation below the mean power reference level specified in 
Sec. 80.211 of the rules.
    Step (7) Record how the test was performed, instrument settings and 
the occupied bandwidth in kHz and the 3 dB bandwidth of the carrier in 
Hz. (See Sec. 2.1517 of this part).
    Step (8) Repeat Steps 1 through 7 for the signal at 243 MHz.

    (c) Signal enhancement test.

    The setup specified in Sec. 2.1515(a) is to be used in this method 
of measuring signal enhancement. Other methods may be used if shown to 
give results equivalent to or more accurate than this method.

    Step (1) Activate the EPIRB and locate the carrier frequency at 
121.5 MHz on the spectrum analyzer. Adjust location of receiving antenna 
and spectrum analyzer controls to obtain a suitable signal level (i.e., 
a level which will not overload the analyzer, but is far enough above 
the noise floor to allow sidebands at least 40 dB below the carrier to 
be viewed).
    Step (2) Set the spectrum analyzer controls as follows:

I.F. bandwidth: 10 kHz
Video filter: OFF or as wide as possible
Scan time: 100 ms./div.
Amplitude scale: 5 dB/div.
Scan width: 10 kHz/div.
Center frequency: 121.5 MHz

    Step (3) Record the amplitude in dBm.
    Step (4) Calculate the total power output by adding 10 log(D), where 
D is the modulation duty cycle determined in Sec. 2.1513(d) of this 
part, to the recorded signal level.
    Step (5) Set the spectrum analyzer controls as follows:

I.F. bandwidth: 60 Hz or less
Video filter: OFF or as wide as possible
Scan time: 10 sec./div.
Amplitude scale: 5 dB/div.
Scan width: 20 Hz/div.
Center frequency: 121.5 MHz

    Step (6) Measure and record the carrier power dBm as displayed on 
the spectrum analyzer.
    Step (7) Calculate the ratio of carrier power to total power from 
Steps 4 and 6 using the following formula:
[GRAPHIC] [TIFF OMITTED] TC03JN91.004

dBC = carrier power in step 6
dBT = total power in step 4

    Step (8) Record instrument settings, sample calculation and the 
percent of power within &177;30 Hz at 121.5 MHz or &177;60 
Hz at 243 MHz of the carrier frequency.
    Step (9) Repeat the above measurement Steps 1 through 8 for 243 MHz. 
For the higher frequency, the I.F. bandwidth in step 5 must be 120 Hz or 
less.

    (d) Carrier frequency test.
    The setup specified in Sec. 2.1515(a) is to be used in measuring the 
carrier frequency.

    Step (1) Activate the EPIRB and locate the 121.5 MHz signal on the 
spectrum analyzer. Adjust location of receiving antenna and spectrum 
analyzer controls to obtain a suitable signal level.
    Step (2) Set the spectrum analyzer controls as follows:

I.F. bandwidth: 100 Hz
Video filter: OFF or as wide as possible
Scan time: 10 sec./div.

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Amplitude scale: 10 dB/div.
Scan width: 20 Hz/div.
Center frequency: 121.5 MHz

    Step (3) Combine the output of the signal generator with the EPIRB 
signal at the input to the spectrum analyzer.
    Step (4) Adjust amplitude and frequency of signal generator output 
to determine center of carrier frequency component.
    Step (5) Measure signal generator frequency with frequency counter 
with accuracy of 5 PPM or better and record as carrier frequency.
    Step (6) If applicable, change the type of modulation of the EPIRB 
and record the shift in carrier frequency as observed on the spectrum 
analyzer display.
    Step (7) Repeat the above measurement Steps 1 through 6 for 243 MHz.
[ 56 FR 11683 , Mar. 20, 1991;  60 FR 47302 , Sept. 12, 1995]

                  Data Recording/Reporting Requirements