EndRun Meridian II, Руководство пользователя

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M e r i d i a n I I U s e r M a n u a l 206
A P P E N D I X K
207 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 Analog Time Code Output Module:
Quantity: 4 outputs.
Drive: 1 V
RMS
into 50Ω.
Frequency: 1 kHz.
Alignment: Within 5 us of 1 PPS.
User-Selectable Formats: IRIG-B (122, 123, IEEE-1344 compliant), NASA-36, and 2137.
Connector: Rear-panel BNC jack.
Note: See Chapter 10 - Rear-Panel I/O, Analog Time Code Output Module for more information.
Optional Digital Output Module:
Quantity: 4 outputs.
Signal: TTL into 50Ω, RS-232 or RS-422 (RS-422 available in 1U chassis only).
TTL (50 Ω to GND): V
OL
(max)=0.2V, V
OH
(min)=2.8V, V
OH
(nominal)=3.0V, V
OH
(max)=3.3V.
RS-232: +/- 5V into 3kΩ; Slew Rate: 30 V/us.
RS-422 (100Ω differential): V
DIFF
(min) = 2.1V, V
DIFF
(Nom) = 2.4V, V
DIFF
(max) = 3.2V,
V
OUT
(max) = 3.5V referenced to GND.
Type of output: Programmable Pulse Output (PPO), Time Code, Direct Digital Synthesizer (DDS) or
a preset rate, such as a 10MPPS. Output types are described below.
Rise Time: < 2 nanoseconds (TTL). < 3 nanoseconds (RS-422).
Connector (TTL): Rear-panel BNC jack.
Connector (RS-232/RS-422): Rear-panel DB9M.
Pinout (RS-232): Pin 1 is Output A, Pin 2 is Output B, Pin 3 is Output C, Pin 4 is Output D.
Pinout (RS-422): Pin 1 is Output A+, Pin 2 is Output B+, Pin 3 is Output C+, Pin 4 is Output D+,
Pin 5 is Ground, Pin 6 is Output A-, Pin 7 is Output B-, Pin 8 is Output C-,
Pin 9 is Output D-.
Note: See Chapter 10 - Rear-Panel I/O, Digital Output Module for more information.
Programmable Pulse Output:
Rate: User selectable to 1, 10, 100, 1K, 10K, 100K, 1M, 5M, 10M PPS, 1PPM, 1PP2S, Inv1PPS*
Duty Cycle: 50% except 1PPS which mimics the width of the standard 1PPS Output and
1PPM which is 1 second wide.
Alignment: Within 5 ns of the other TTL outputs in this unit (except the optional DDS).
Stability: TDEV < 10 ns, τ < 10
5
seconds, σ
y
(
τ
) < 6.0x10
-14
@
τ
=10
5
secs.
Alignment (TTL/RS-422): Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Alignment (RS-232): The actual realized alignment is a function of the zero-crossing delay as
specified above (primarily due to the RS232 slew rate limit) and the actual receiver detection
threshold. The alignment of synthesized rate pulses remains fixed following each system
initialization, but its relationship to other pulse outputs is non-deterministic.
*Inverted 1PPS (Falling edge on-time) is not available in the 2U.
Digital Time Code (DC-Level Shift):
Format: User-selectable, IRIG-B (002, 003, IEEE-1344 compliant), NASA-36, or 2137.
Alignment (TTL/RS-422): Within 5 ns of the other TTL outputs in this unit (except DDS, if any).
Alignment (RS-232): See Alignment (RS-232) above.
Direct Digital Synthesizer (DDS):
Rate: User-selectable, 1 PPS to 10 MPPS in 1 PPS steps (per system DDS setting).
Duty Cycle: 50%.
Accuracy: < 6x10
-14
to UTC for 100k second averaging times when locked.
Alignment: DDS rates are NOT aligned with the other pulse rates in this unit.