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ues showing the saved state of internal registers. These
are for factory use.
3.9 Signal Outputs. The 2960AR has three front
panel outputs of 10MHz, 10MHz and 5MHz. Each
has a nominal amplitude of 1Vrms into 50Ω. The
2965AR has three front panel outputs of 10MHz,
5MHz and a 50MHz synthesized output. Each has a
nominal amplitude of 1Vrms into 50Ω.
3.10 See section 5.0 for the rear panel 1pps IN and
OUT characteristics and use.
4.0
Operation
4.1 Power on. After power is applied, the 2960AR/
2965AR POWER OK LED will illuminate green.
This indicates that the applied line power is within
tolerance and the unit is functioning.
4.2 Rubidium Warm-up. After power is applied,
the 2960AR/2965AR will take up to 20 minutes to
reach Rubidium Lock. During Rubidium warm-up
time, the front panel LED labelled RUBIDIUM
LOCK will illuminate red. When the lock has been
achieved (∆f/f<±1x10
green. This function is independent of 1pps tracking.
During the Rubidium locking process, the front
panel RUBIDIUM LOCK LED may switch between
red and green. A steady green indicates LOCK.
4.3 Proper operation in stand-alone mode, without
a 1pps connection, is indicated by a green POWER
OK LED and a green RUBIDIUM LOCK LED.
The 1pps LED will remain off.
The 2960AR and 2965AR will meet their specified
accuracy within a few hours after power-up. For
applications requiring verification of long-term
stability, the periods shown in the specifications will
have to be met.
4.4 See the section "1pps Operation," below, for
details on 1pps connections and operation.
NOVATECH INSTRUMENTS, INC.
-8
), this LED will illuminate
NOTE:
NOTE:
4.5 Serial control of Synthesizer (2965AR only).
The user host computer software must properly for-
mat the serial commands. Incorrect formatting will
result in an error code being returned. See Table 1
for a list of RS232 error codes.
4.6 Depending upon your host, the 2965AR may
not be able to keep up with serial characters. For
maximum interface speed, it is suggested that Echo-
ing be disabled by the "E D" command. This will
allow the host to send characters at a faster rate.
Flow control must be provided by the host. The
2965AR will respond with an "OK" for a correctly
received data command. If your host software parses
this "OK", you will be assured that the command
has been correctly received and you may send your
next command. You will have to verify correct oper-
ation at your host rate.
5.0
1pps Operation
5.1
1pps In and Out. Both the 2960AR and
2965AR are equipped with rear panel BNC recepta-
cles which accept a 1pps input and provide a 1pps
output. Use of 1pps allows synchronization of multi-
ple 2960AR and 2965AR, as well as providing a
means of auto-calibration.
5.2 The 2960AR and the 2965AR will accept a
long-term stable 1pps signal, typically derived from
a GPS (global positioning system) receiver or from
another frequency standard. Both units will auto-
adapt to the supplied 1pps and adjust the internal
Rubidium Oscillator to match the long term average
frequency derived from the 1pps. The auto-adaptive
algorithm selects the best tuning time constant based
upon the stability of your supplied 1pps.
5.3 For low-jitter 1pps inputs (<20ns), the approxi-
mate tuning time constant will be 1,000 seconds. A
typical timing receiver system, such as the GPS1
(with approximately 100ns peak-peak 1pps jitter),
requires a time constant of approximately 10,000
seconds (about 3 hours) for optimum tracking.
5.4
For noisier 1pps inputs, such as those from
standard GPS receivers not intended for timing
applications, the time constant may increase to
100,000 seconds. If the input is too noisy, as deter-
5
2960AR/2965AR Manual, 13-Jul-2004
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