EndRun Meridian II, User Manual

Page: 225 / 240

M e r i d i a n I I U s e r M a n u a l 204
A P P E N D I X K
205 M e r i d i a n I I U s e r M a n u a l
S P E C I F I C A T I O N S
Optional Direct Digital Synthesizer (DDS) Output (CPU Module):
Signal: Positive TTL pulse into 50 Ω or RS-422.
TTL (50 Ω to GND): V
OL
(max)=0.4V, V
OH
(min)=2.4V, V
OH
(nom)=2.5V, V
OH
(max)=3.0V.
RS-422 (100 Ω differential): V
DIFF
(min)=2.1V, V
DIFF
(nom)=2.4V, V
DIFF
(max)=3.0V,
V
OUT
(max)=3.3V referenced to GND.
Rate: User selectable 1 PPS to 10MPPS in 1PPS steps (per system DDS setting).
Accuracy: < 6x10
-14
to UTC for 100k second averaging times when locked.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Alignment: DDS rates are NOT aligned with the other pulse rates in this unit.
Connector: Rear-panel BNC jack labeled “DDS”.
Note: To change the selection refer to Chapter 10 - Rear-Panel I/O, Direct Digital Synthesizer .
Optional 10 MPPS Rate Output (CPU Module):
Signal: Positive TTL pulse into 50 Ω or RS-422.
TTL (50 Ω to GND): V
OL
(max)=0.4V, V
OH
(min)=2.4V, V
OH
(nom)=2.5V, V
OH
(max)=3.0V.
RS-422 (100 Ω differential): V
DIFF
(min)=2.1V, V
DIFF
(nom)=2.4V, V
DIFF
(max)=3.0V,
V
OUT
(max)=3.3V referenced to GND.
Rate: An on-time 10 MPPS pulse rate.
Accuracy: < 6x10
-14
to UTC for 100k second averaging times when locked.
Stability: TDEV < 10 ns @ τ < 10
5
seconds, σ
y
(
τ
) < 6.0x10
-14
@
τ
=10
5
secs.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Alignment: Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Connector: Rear-panel BNC jack labeled “10MPPS”.
Note: For more information refer to Chapter 10 - Rear-Panel I/O, 10 MPPS Output Option .
Optional Alarm Output (CPU Module):
Signal: MMBT2222A open collector, grounded emitter. High impedance in alarm state.
Voltage: 40 VDC, maximum.
Saturation Current: 100 mA, maximum.
Connector: Rear-panel BNC jack or terminal block labeled “ALARM”.
Note: For more information refer to Chapter 10 - Rear-Panel I/O, Alarm Output .
Optional Serial Time Output (CPU Module):
Signal: Output only port at RS-232 (±5V) or RS-422 levels.
RS-422 (100 Ω differential): V
DIFF
(min)=2.1V, V
DIFF
(nom)=2.4V, V
DIFF
(max)=3.0V,
V
OUT
(max)=3.3V referenced to GND.
Baud Rate: User Selectable to 4800, 9600, 19200 or 57600.
Parity: User Selectable to Odd, Even or None.
ASCII Formats: User-Selectable to Sysplex, EndRun, EndRunX, Truetime, NENA or NMEA.
Accuracy: The “on-time” characters starts transmitting within the first 20 microsecs of each second.
Connector (RS-232): Rear-panel DB-9M connector labeled “SERIAL TIME”.
Pinout (RS-232): Pin 3 is Transmit Data. Pin 5 is GND.
Connector (RS-422): Rear-panel DB-9M connector labeled “SERIAL TIME (RS-422)”.
Pinout (RS-422): Pin 3 is +signal. Pin 6 is -signal. Pin 5 is GND.
Note: For more information refer to Chapter 10 - Rear-Panel I/O, Serial Time Output .