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Dynamic Reserve Sensitivity Range
LOW 1 µV through 500 mV
NORM 100 nV through 50 mV
HIGH 100 nV through 5 mV
Dynamic Reserve
The dynamic reserve (DR) is set using the keys in
the DYNAMIC RESERVE section. The reserve is
displayed by the three indicator LED's, HIGH,
NORM, LOW. Only those dynamic reserve
settings available for the sensitivity are allowed
(see above table). For example, when the
sensitivity is 500 mV, the DR will always be LOW.
The dynamic reserve and output stability of each
setting are shown below.
Setting Dynamic Reserve Output Stability
(ppm/°C)
LOW 20 dB 5
NORM 40 dB 50
HIGH 60 dB 500
Since a higher DR results in degraded output
stability, you should use the lowest DR setting for
which there is no overload indication. Note that
using the Bandpass Filter provides about 20dB of
additional DR and so allows you to operate with a
lower DR setting.
Status
There are five STATUS LED's.
OVLD indicates a signal overload. This condition
can occur when the signal is too large, the
sensitivity is too high, the dynamic reserve is too
low, the offset is on, the expand is on, the time
constant is not large enough, or the ENBW is too
large.
UNLK indicates that the reference oscillator is not
phase locked to the external reference input. This
can occur if the reference amplitude is too low, the
frequency is out of range, or the trigger mode is
incorrect for the reference signal waveform.
ERR flashes when an error occurs on one of the
computer interfaces, such as an incorrect
command, invalid parameter, etc.
ACT indicates activity on the computer interfaces.
This LED blinks every time a character is received
by the SR510 or transmitted by the SR510.
REM indicates that the unit is in the remote state
and that the front panel controls are not operative.
There are two remote states. The Remote-With-
Lockout will not allow any inputs from the front
panel. The Remote-Without-Lockout command
allows you to return the front panel to operation by
pressing the DISPLAY UP key.
Diplay Select
The keys in the DISPLAY section select the
parameter to be displayed on the output meters
and the output on the OUTPUT BNC connector.
The displayed parameter is indicated by one of the
three LED’s and can be either the demodulator
output (X), the offset (OFST), or the rms noise
(NOISE). When displaying NOISE, the equivalent
noise bandwidth (ENBW) is selected in the TIME
CONSTANT section.
Output
The analog output is available at the OUTPUT
BNC. The input signal equal to the selected full
scale sensitivity will generate a ±10V output when
the EXPAND function is off. With the EXPAND on,
the output is multiplied by 10, effectively
increasing the full scale sensitivity by 10. The
ouptut impedance is <1Ω and the output current is
limited to 20 mA.
The analog meter always displays the OUTPUT
voltage. Accuracy is 2% of full scale.
The OUTPUT LCD display provides a read-out of
the displayed parameter in real units. The scale of
the displayed quantity is indicated by the three
scale LED's to the right of the display. This read-
out auto ranges and will reflect the sensitivity
added when the EXPAND function is on.
Expand
The output EXPAND is toggled by pressing the
key in the EXPAND section. The expand status is
indicated by the X10, expand on, and the X1,
expand off, LED's.
REL Function
The relative (auto-zero) function is toggled by the
key in the REL section. Every time the rel status
LED is turned ON the offset value is set to minus
the value of the X output, thus zeroing the X
output. This function will work even if X is not the