X
X
L
L
D
D
C
C
M
M
A
A
N
N
.
.
d
d
o
o
c
c
1
1
-
-
1
1
0
0
R
R
E
E
V
V
E
E
The input frequency for this input may be 1, 5, or 10 MHz. The signal may be TTL levels or a sine
wave with an amplitude of 1.0 to 5.0 Vp-p. The user should specify the desired input impedance of
either 1 k
Ω
or 50
Ω
(set with 87-6XX jumper JP10 -- factory default = 50
Ω
).
CAUTION:
If the external oscillator is selected "ON" via Function 07 and
if no input is present
on the
External Oscillator Input connector (EXTOSC), the operation of the unit will be unpredictable. The
jumper settings
MUST
match the mode set by Function 07.
Frequency:
1, 5 or 10 MHz
Level:
1 to 5 Vp-p
Impedance:
1K or 50
Ω
(user-specified)
1-51 TIME INTERVAL/EVENT TIMING INPUT (OPTION)
This input option is connected to a rear panel BNC connector. This input will accept an externally
applied 1 PPS or Event input signal for measurement against the GPS derived UTC time. The signal
may have a minimum pulse width of 100 ns. It must have a TTL low level and its high level must be in
the range from a TTL high level to 10 VDC. The input impedance is selectable at 1 k
Ω
or 50
Ω
and
should be user specified (refer to 87-6XX configuration drawing JP7 -- factory default = 50
Ω
). The
rising edge of the pulse is measured with respect to the XL-DC time to 30 ns. Refer to Keypad or Serial
Function F28 for details concerning the use of this input.
Pulse width:
100 ns, minimum
Active Edge:
Rising
High Level:
TTL to 10 VDC
Low Level:
TTL
Hysteresis:
50 mV
Impedance: 1
k
Ω
or 50
Ω
(user-specified)
Resolution:
30 ns, single shot
Accuracy:
150 ns + 30 ns/2
1-52 FREQUENCY MEASUREMENT INPUT (OPTION)
This input option is connected to a rear panel BNC connector. This input will accept an externally
applied signal for measurement with respect to the XL-DC disciplined frequency. The input frequency
may be 1, 5, or 10 MHz. The resolution of the measurements is 6 x 10
-11
at 1 s averaging. The input
signal may be TTL levels or a sine wave with an amplitude of 1.0 to 5.0 Vp-p. The input impedance is
selectable at 1 k
Ω
or 50
Ω
(refer to 87-6XX configuration drawing JP9 -- factory default = 50
Ω
). Refer
to Keypad or Serial Function 29 for details concerning the use of this input.
Resolution:
6 x 10E-11@ 1 Second Interval
Accuracy:
3 x 10-12
Stability:
Same as Frequency & Timing Stability
Impedance:
1 k
Ω
or 50
Ω
(user-specified)
Frequency:
1, 5, or 10 MHz
1-53 through 1-59 reserved
Содержание 151-600
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