Crown Audio IQ-P.I.P.-SMT - Manual (Page 29)

Page 29
IQ P.I.P.–SMT
5 Technical Information
The purpose of the IQ–P.I.P.–SMT is
to enable an IQ System to control and
monitor a P.I.P.-compatible amplifier.
The exact features of your unit are
determined by the firmware in its mi-
croprocessor. Here is a typical list of
features:
❏ Control the audio signal polarity.
❏ Control the high-voltage power
supplies.
❏ Control the DSPI LED.
❏ Control and monitor the AUX
port.
In addition, all units can monitor
these parameters:
❏ Monitor the input level to the
IQ–P.I.P.–SMT.
❏ Monitor the output level from
the amplifier.
❏ Monitor the ODEP level.
❏ Monitor the IOC.
5.1 Audio Signals
Balanced and unbalanced audio sig-
nals enter the module at the XLR con-
nectors. From these connectors, the
signals are RFI filtered and fed into a
balanced to single-ended conversion
stage. Additional gain and/or phan-
tom power for a microphone are also
provided in this stage. From this
point, the audio signal is sent to a
monitor input (discussed below) and
also to a digitally controlled attenua-
tor. Following the attenuator, the sig-
nals pass through a final output buffer
stage, which also can invert the po-
larity of the signal when required. The
audio signal is then fed through the
P.I.P. edge card connector and into
the amplifier.
5.2 Amplifier Monitoring:
“Monitor Inputs”
The IQ–P.I.P.–SMT can monitor the
status of the amplifier using a num-
ber of “monitor inputs.” There are two
types of signals—audio and status.
The audio signals that are monitored
are the input to the
P.I.P. and the out-
put of the amplifier. These signals en-
ter the
P.I.P. and are fed into a
precision peak detector which in-
sures that instantaneous signal
peaks are not “missed” by the
P.I.P.
The detector outputs are then fed
through a multiplexer into a logarith-
mic conversion circuit for dynamic
range scaling. The output of this cir-
cuit is then fed into the A/D converter
on the microprocessor, where the sig-
nal is converted and sent to the host
computer via the Crown Bus.
The status signals that are monitored
are
ODEP level, IOC status and VCC
status. These signals enter the P.I.P.,
pass through a buffer stage, and are
fed into the A/D converter on the mi-
croprocessor. The signals are then
converted and sent to the host com-
puter via the Crown Bus.
5.3 Amplifier Control
The IQ–P.I.P.–SMT can control the fol-
lowing functions: audio level, audio
polarity, high-voltage power supplies,
DSPI and the AUX port. These func-
tions are controlled using ports on the
microprocessor and some external
support circuitry. The audio level is
controlled by the microprocessor
through a digitally controlled analog
attenuator. The DSPI LED flashes
whenever a valid IQ command has
been received and can be forced to
stay on to facilitate diagnosis of
Crown Bus wiring problems.