BDS
Cal
Cart
4
Theory of Operation
The
BDS
Cal
Cart
is
a
real
‐
time
RF
measurement
system
that
consists
of
a
sensor,
receiver
and
a
load.
The
sensor
simultaneously
measures
voltage
and
current
(both
magnitude
and
phase
of
each)
and
sends
the
data
to
the
receiver.
The
BDS
Cal
Cart
is
calibrated
as
a
system
and
the
components
are
not
interchangeable.
The
receiver
processes
the
sensor
data
and
passes
the
data
to
the
laptop.
The
receiver
consists
of
RF
input
conditioning
circuits,
A/D
converters,
a
high
‐
speed
signal
processor,
and
input
/
output
connectors.
See
The
A/D
converters
convert
the
analog
RF
signal
to
digital
information
for
processing;
the
high
‐
speed
signal
processor
converts
the
signal
from
the
time
domain
to
the
frequency
domain
while
maintaining
the
correct
phase
relationship
of
each
harmonic
to
its
fundamental
frequency.
The
output
of
the
receiver
contains
information
about
the
RF
including
up
to
three
fundamental
frequencies
(amplitude
of
both
voltage
and
current
and
their
phase
for
each
fundamental
frequency)
and
up
to
10
overtones
for
each
fundamental
frequency
(amplitude
of
both
voltage
and
current
and
their
phase
for
each
harmonic,
and
also
the
phase
relationship
of
each
harmonic
to
the
voltage
component
of
its
specific
fundamental
frequency).
With
this
data
set
(voltage,
current,
and
phase),
power
(
p
v i
cos
=
)
and
impedance
(
Z
v i
=
)
can
be
determined
for
each
fundamental
and
harmonic
frequency.
Users
can
choose
number
of
fundamental
frequencies
(up
to
three)
and
associated
harmonics
(up
to
10
for
each
fundamental
frequency)
that
are
acquired
and
processed.
Choosing
a
small
number
of
fundamental
and
harmonic
frequencies
reduces
the
computing
time
and,
therefore,
provides
output
data
faster
than
choosing
a
larger
number
of
fundamental
and
harmonic
frequencies.
See
.
Figure 2 Receiver Block Diagram
