Manual

ANSI C63.17-2006
Methods of Measurement of the Electromagnetic and Operational Compatibility of UPCS Devices
B.2
B.2.1
Power limits
Transmit power limits
For EUTs with antenna gain less than a certain value g, which is specified in the applicable regulations,
33
the maximum EUT transmit power at the transmit antenna terminals is P
max
= 10
−4
B
W, where B is the
EUT emission bandwidth in hertz. In decibels referenced to 1 mW, P
max
= 5 log B − 10. If the antenna gain
exceeds g, then the actual EUT transmit power P
EUT
must be reduced below this limit by the amount that
the directive gain of the EUT transmit antenna (relative to an isotropic antenna) exceeds a certain value g,
as shown in the following equation:
gGP
gGgGP
PPP
A
AA
≤
>−−
=≤
when ,
when ),(
max
max
limitlimitEUT
where
(B.1)
where
G
A
is the maximum directional gain of the EUT transmit antenna
B.2.2
B.2.3
Monitoring threshold limits
The maximum monitoring threshold for an EUT transmitting the maximum allowed power is M
L
dB or
M
U
dB above kT
0
B, where k = 1.38 × 10
−23
W/K Hz, (Boltzmann’s constant), T
0
= 290 K (a defined
absolute temperature), and B is the measured emissions bandwidth (in hertz). The selection of M
L
or M
U
is
made based on whether the EUT implements the LIC algorithm and how many channels a system built with
the EUT realizes. If the EUT does not implement the LIC algorithm or if a system built with the EUT
realizes less than 40 channels, then the selection is limited to M
L
; otherwise, M
L
or M
U
may be selected at
the manufacturer’s discretion.
For an EUT transmitting less than the maximum permitted power, the monitoring threshold limit increases
by the difference between P
limit
and P
EUT
. The effect of the rules, therefore, is to place an upper bound on
the sum of the EUT transmit power and monitoring threshold.
A provision is made in the EUT test procedures for an uncertainty margin U
M
. This margin is provided to
account for the effects of measurement noise in the EUT’s operations, the intent being to allow the
manufacturer to implement EUTs with the thresholds as defined without having to incrementally reduce the
implemented threshold so as to allow for statistical variation in measurement results and other sources of
measurement error.
EIRP and electric field (E-field) threshold limits for radiated tests
For an EUT with a nondetachable antenna and without a test connector added to the EUT for the purposes
of evaluation, the transmit power must be measured in terms of EIRP referenced to an equivalent conducted
level according to the calibration of the radiated test facility.
Measurement of the monitoring thresholds must be based on an equivalent E-field incident on the transmit
antenna, generated according to the calibration of the radiated test facility, or using the path loss method of
4.4.
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47CFR15.319(e) specifies g = 3 dBi.
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