TDT RZ2, Manual, Page: 160 / 736

3-28 System 3
RX5 Pentusa Base Station
booting status (Booting DSP) or alert the user when the device's microcode needs
to be reprogrammed (Firmware Blank).
Status Indicators
Cyc:
cycle usage
Ovr: processor cycle overages
Bus%: percentage of internal device's bus capacity used
I/O%: percentage of data transfer capacity used
Important! The status lights will flash (~3 times a second) to alert the user when a device
goes over the cycle usage limit, even if only for a particular cycle. This helps to
identify periodic overages caused by components in time slices.
Fiber Optic Ports
The RX5 base station acquires digitized signals from a Medusa preamplifier over a
fiber optic cable. This provides loss-less signal acquisition between the amplifier and
the base station. Two or four fiber optic ports are provided to support simultaneous
acquisition from up to four preamplifiers. Each port can input up to 16 channels at
a maximum sampling rate of ~25 kHz. The first two ports provide oversampling. See
“Fiber Oversampling”, below for more information.
The fiber optic ports can be used with any of the Medusa preamplifiers including the
RA16PA, RA4PA, or RA8GA. The channel numbers for each port begin at a fixed
offset regardless of the number of channels available on the connected device.
Channels are numbered as follows:
Amp-A
1 – 16
Amp-B 17 – 32
Amp-C 33 – 48
Amp-D 49 - 64
Fiber Oversampling
The fiber optic cable that carries the signals to the fiber optic input ports has a
transfer rate limitation of 6.25 Mbits/s. With 16 channels of data and 16 bits per
sample, this limitation translates to a maximum sample rate of 24.414 kHz.
However, the need may arise to run a circuit at a higher sample rate while still
acquiring data via a fiber optic port. The first two fiber optic ports can oversample
the digitized signals that have already been sampled up to 4X or ~100 kHz. This
will allow an RX5 to run a DSP chain at ~50 kHz or ~100 kHz, and still sample
data acquired through an optically connected preamplifier that digitized the incoming
data stream at a maximum rate of ~25 kHz.
Oversampling is performed on the base station. The signals being acquired will still
be sampled at ~25 kHz on the preamplifier. This means that, even with
oversampling, signals acquired by an optically connected preamplifier are still governed
by the bandwidth and frequency response of the preamplifier.
When acquiring up to 16 channels of data on the first fiber optic input port of the
RX5, the signals will be oversampled 4X to 100 kHz. If data is being acquired only
on the first two fiber optic ports, the signals will be oversampled 2X to ~50 kHz.