Goto Section: 2.1513 | 2.1517 | Table of Contents
FCC 2.1515
Revised as of October 1, 2011
Goto Year:2010 |
2012
§ 2.1515 Spectral measurements.
(a) Set-up. Spectral measurements are to be performed in a shielded
room.
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
log[10](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
§ 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 § 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 § 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 § 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:
[ec03jn91.004.gif]
View or download PDF
dB[C]= carrier power in step 6
dB[T]= total power in step 4
Step (8) Record instrument settings, sample calculation and the percent
of power within +-30 Hz at 121.5 MHz or +-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 § 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.
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
Goto Section: 2.1513 | 2.1517
Goto Year: 2010 |
2012
CiteFind - See documents on FCC website that
cite this rule
Want to support this service?
Thanks!
Report errors in
this rule. Since these rules are converted to HTML by machine, it's possible errors have been made. Please
help us improve these rules by clicking the Report FCC Rule Errors link to report an error.
hallikainen.com
Helping make public information public