Spectracom VelaSync 1232 User Manual page 19

Outputs
CHAPTER 1 • VelaSync User's Manual Rev. 3
IRIG DCLS Input
Accepts IRIG formats A, B, G; NASA36; IEEE 1344 pulse width codes (does
not accept Manchester modulated codes)
RS-485 differential input: –7V to +12 V common mode voltage input range,
200 mV differential voltage threshold
p-p
Single-ended input:
+1.3 V
VIL min
+1.45 V
VIL typ
GPIO Inputs
Amplitude: 0V to +5.5 V input range, +0.8 V
Polarity (selectable): Positive or negative
Input impedance: <150 pF capacitive
50 ns active pulse width minimum; 50 ns minimum between pulses
Repetition rate. More than 10,000 events per second
Resolution: 5 ns
1 PPS Outputs
1Hz pulse, rising edge or falling edge active (selectable)
40 ns to 900 ms active pulse width (selectable, 200 ms default)
Rise time: <10 ns
Signal level: TTL compatible, 4.3 V
[PCIe only: TTL compatible, 2.2 V minimum, base-to-peak into high imped-
ance]
Accuracy: Positive edge within ±[X] nanoseconds of UTC when locked to a
valid 1PPS input reference (for [X], see table below).
Table 1-2:
1 PPS output accuracy
Accuracy to UTC
sigma locked to GPS)
, +2 V
VIH max
, +1.85 V
VIH typ
, base-to-peak into 50 Ω
min
OCXO (Rugged
TCXO OCXO Option, cPCI & VPX
(1- ±50 ±50 ±25 ns
ns ns
1.4 Technical Specifications
, +2.0 V
VIL VIH
only)
7