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3.4 Using the Transmitter’s Broadband Mode
In Broadband Mode, the output from the transmitter is a series of 25
MHz spaced pickets generated by a comb generator. These pickets
will vary in level between -10 dBm and -15 dBm over the frequency
range of 750-1000 MHz.
Broadband Mode is especially useful when testing smaller tabletop
enclosures. With the transmitter operating in the enclosure, a
spectrum analyzer can be used to determine the shield level even if
a cavity resonance should fall within the band.
Transmitter Setup and Power ON
 Attach antenna of suitable frequency range to transmitter BNC
output.
 Open enclosure door. Place unit inside enclosure.
 Rotate POWER switch to ON position to begin transmitting.
 Depress the MODE switch until the MODE status indicates the
unit is in the “bb” mode.
 Depress the ATTEN switch. The ATTEN status reads “0 dB.”
 With the enclosure open, measure the level of the pickets with a
spectrum analyzer. Shield level can be determined by
calculating the drop in picket level after the enclosure door is
closed.
3.5 Monitor Mode Operational Sequence
Monitor mode can be used daily to monitor a relative reference level
to determine if a change in shielding effectiveness has occurred.
First, the shield level of the enclosure must be confirmed using the
shield level mode (see section 3.3). Monitor mode can be used with
a set of permanently installed antennas on each surface of the
enclosure to ensure the shield level remains constant. Verify that
the monitor antennas are installed and connected to the switch
assembly inputs ANT1 – ANT12. Note: The antennas are pre-
installed on site and not included in the PAMS.
A relative reference level must first be established to be used as a
baseline for daily comparison. Every time a monitor measurement is
to be made, the transmitter and receiver should be initialized using
the same procedure and coax cables that were used to establish the
baseline.