CT1815 Datasheet, PDF (2/7 Pages) Aeroflex Circuit Technology – CT1815 10MHz Low Level Serial Interface for MIL-STD-1397 Type D

Transmission
The CT1815 accepts synchronous NRZ Data in
conjunction with two clocks signals. The NRZ data
stream is then converted to Manchester code which
is transformer coupled to a 75 ohm Tri-axial cable for
transmission up to 1000 ft.
The transmitter may be placed into standby
condition. This reduces power consumption by
approximately 600mW. Power management is made
available via two standard TTL input pins. The
Receiver is always active and is not affected by the
power management circuitry.
The transceiver is matched for 75 ohm operation
over a wide band of frequencies. This condition is
maintained with power on and off.
Reception
The CT1815 receiver section accepts a bipolar
signal which is level detected and passed to the
serial decoder. The decoder section reconstructs
the data and strips the clock from the serial stream.
An NRZ decoded data stream is then produced
synchronously with a recovered clock. The receiver
is designed to meet the MIL-STD-1397 Type D
requirements.
Electrical Requirements
The specification detailed herein encompasses a
hybrid Transceiver/Encoder-Decoder designed to
meet the requirements of the MIL-STD-1397 Type D.
The transceiver is transformer coupled to the
specified triaxial cable and is screened to the
individual test methods of MIL-STD-883
See Figure 1 for Block Diagram. Inputs and
Outputs are all Synchronous NRZ DATA STREAMS
Transformer Isolation
The CT1815 is connected with pin 3 and pin 32 to
the ACT15-1031 transformer secondary winding.
The center tap of the secondary winding is
connected to +5 volts. For matching 75Ω load
operation, a 78Ω resistor must be placed across the
primary winding of the transformer.
Encoder Timing / Transmitter Specification
Symbol
t1
t2
t3
t4
t5
t6
tw1
tw2
Va
T
Ts
Te
T/2
Tr
Tf
Vs
Tos
Tdtx
Zo
Parameter / Condition
Encode Timing
Input data set-up time
Encode clock set-up time
Encode envelope set-up time
Encode envelope turn-off time
Transmitter activation set-up time
Transmitter deactivation hold-time
20 MHz gated CK pulse width high
Encoder shift CK pulse width high
Output Signals
Output amplitude (see Figure 2)
Pulse period
Width of 1st positive half bit
Width of last half bit
Half pulse period
Pulse rise time
Pulse fall time
Voltage overshoot
Offset Voltage 2T after last zero crossing
Delay from 20 MHz clock input to data output on
transformer secondary
Output Impedance
Min Typ Max Unit
10
40 ns
10
40 ns
10
40 ns
10
35 ns
150
ns
50
ns
20
30 ns
45
55 ns
2.75 3.25 3.75 V
97 100 103 ns
45
65 ns
47
65 ns
47 50 53 ns
2.0 V/ns
2.0 V/ns
350 mV
150 mV
20 55 ns
70 75 80 Ω
Aeroflex Circuit Technology
2
SCDCT1815 REV A 6/12/98 Plainview NY [phone]