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Correction of Measured Values - The spectrum analyzer calibration is in units of dBm absolute.
Published antenna factor, measured cable loss and preamplifier gain are in units of dB. All equipment is
referenced to a 50-ohm characteristic impedance; therefore, any impedance terms will factor out of any
calculations. Also, balun loss is included in the antenna factor, so this term will not appear in any
calculation.
To obtain field strength, the reference (50 ohm system) 1 uV = 0 dBuV = -107 dBm is used.
For a given frequency: antenna factor, cable loss, preamplifier gain (if used) and a 9.54 dB gain factor (3
meters to 1 meter field strength conversion) when required are factored into the spectrum analyzer
reading, resulting in a field strength in units of dBm.
Field strength reading (dBm) + 107 dB = dBuV, using 0 dBuV = 1 uV/meter at a specified distance as
reference.
All of the equipment was calibrated to NBS-traceable factory specifications prior to the date of
measurement.
IV
MEASUREMENT PROCEDURE
Transmitters
1.
Set the DIP-switch rockers of the transmitter (if needed) to all ON, jam the button in the ON
position, and place the transmitter on the test stand.
2.
Tune the antenna (if required).
3.
Tune the spectrum analyzer.
4.
Adjust the antenna height and polarization for peak field strength.
5.
Rotate the turntable to orient the transmitter for the highest reading.
6.
Record the observed peak emission.
7.
Record the screen image (if required).
Spectrum Analyzer Control Settings:
Tuning:
Bandwidth
Scan Width:
Input Attenuator:
Scan Time:
Reference Level:
Display Mode:
Video Filter:
Scan Mode:
Scan Trigger:
As required
100 KHz for Field Strength,
100 KHz/div (may be different when tuning or adjusting
display for photographs)
10 dB
50 mSec. sweep
0 dBm
Log 10 dB/division
OFF
Internal
Auto
LINEAR LLC
FCC ID: EF4 SST00116
SECTION 6
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