STEL-1209/CE Intel, STEL-1209/CE Datasheet - Page 3

• Manufacturer Part Number: STEL-1209/CE
• Description: BPSK/QPSK/16 QAM Burst Modulator Assembly
• Manufacturer: Intel

DESCRIPTION
The STEL-1209 is the latest member in Stanford
Telecom's line of BPSK/QPSK Burst Modulator board
level products. It uses the STEL-1109 ASIC to provide
all the convenience of
16QAM up-stream modulation with a maximum data
rate of 10 Mbps, 20 Mbps, and 40 Mbps; respectively.
The STEL-1109 has a Reed-Solomon encoder, a
scrambler, a differential encoder, a 10 bit DAC, and
many
communication systems that satisfy today's demanding
requirements. For further feature details please refer to
the STEL-1109 ASIC data sheet.
Besides the STEL-1109, there is additional logic circuitry
implemented in Altera's FPGA to provide burst BPSK,
QPSK, and 16QAM modulation modes. Several
improvements in these burst modulation modes are
included; e.g. external/internal preamble and data
sources; variable bursts quantity (includes single to
10 -million and auto repeat); variable packet length,
guard time, and preamble size (including zero
preamble size). This flexibility allows the STEL-1209 to
be
environment. Connectors J3 and J4 are digital test pins
provided
control/signal timing relationships.
With a 0.35 micron ASIC process the STEL-1109 can
support a maximum clock frequency of 165 MHz. The
frequency
programmable between 5 to 65 MHz; the upper limit is
approximately 40% of the master clock. The STEL-1209
has a 102.4 MHz crystal oscillator on-board. Hence, its
maximum modulated carrier frequency can be set to
40 MHz. However, an external clock (+10 to +13 dBm)
can be selected as the master (through connector J2 and
jumper JP4) and carrier frequency of 65 MHz can be
achieved easily. An obvious difference between this
board and its predecessor (STEL-1208) is the absence of
a DAC. A 10 bit DAC is built in the STEL-1109 and
observable spur level is -50 dB or better. It has a pair of
differential current outputs which swings ±0.96 volt
peak-to-peak at 50 ohm termination. Single-ended
output of the DAC (using transformer T1 as a double to
single-ended converter) can be obtained from J7
(expects 50 or 75 ohm termination impedance from
instrumentation). Also included is a choice between
customized
more
for
of
features
the
easy
easily
output
monitoring
supporting BPSK, QPSK, or
needed
into
modulated
customers'
to
of
build
the
carrier
specific
robust
burst
is
3
two output low pass filters (jumper JP5 and JP6) with
cut-off frequency at 42 and 65 MHz. The output of the
filter is amplified and is obtainable from J5 (75 ohm
source impedance). JP3 routes the DAC output to
either J7 or J5.
The board (running at 102.4 MHz in continuous
modulation mode) takes about 430 mA at the 5 volt
supply. Power is supplied to the board through JP1. Its
pins are clearly labeled on the board (pin 1 = -5 volt, pin
2 = AGND, pin 3 = DGND, pin 4 = VCC (+5 volt)).
Reversing the polarity of the supply pins would cause
damage to the board. When clock enable line is taken
low (grounded), the board consumes 200 mA or less.
Current drawn on the -5 volt supply is 10 mA. There
are two 5 volt to 3.3 volt converters on the board and
the design serves to demonstrate the inter-operability of
the STEL-1109 in a 5 volt or 3.3 volt system. The STEL-
1109 ASIC, which is a 3.3V device, consumes 1.8
mA/MHz in continuous mode. Current consumption
by the ASIC can be easily measured by connecting pin 2
of JP9 (see package outline) to a 3.3 V power supply
that has a current meter.
STEL-1209's operating mode can be modified by
writing new values to the STEL-1109 and the burst
controller's registers.
written through a Graphical User Interface (GUI)
program that comes with the STEL-1209 board. The
GUI software allows the user to select different
modulation methods, preamble size, interpolation ratio,
etc. with the ease of button clicking on a Personal
Computer running Microsoft's Windows 95 operating
system. A serial cable with 9 pin D-sub connector must
be connected between P2 of the STEL -1209 and the
PC's COM port for the GUI software to work. At power
up or upon reset, the STEL -1209 is automatically
loaded with default values to give repeating QPSK
burst modulation (50% duty cycle) centered at 10 MHz
(master mode). This default mode allows the STEL-
1209 to communicate with the STEL -9244, up-stream
burst demodulator. External data must be provided to
connector J1 (75 ohm unipolar unbalance) to complete
the communication loop. Clock for the external data is
provided through connector J6 (75 ohm unipolar
unbalance).
These registers can be read and
STEL-1209