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STATUS INDICATORS
There are a number of status indicators which are
displayed at the bottom of the screen. These
include the scan, unlock, and overload indicators,
the reference frequency and source, and interface
status.
Stop • Run 1 • Run • Pause • Done
When the data buffers are reset (pressing
[PAUSE RESET] while paused or done), then
Stop will be indicated.
When a scan is in progress in the 1 Shot mode,
Run 1 is indicated. The storage of trace data in the
buffer continues until the scan is complete at
which time Done is displayed.
If a Loop scan is in progress, Run is displayed.
The storage of trace data in the buffer may contin-
ues indefinitely. When the buffer fills, the oldest
data is written over.
If the scan is paused (with the [PAUSE/RESET]
key for instance), then the Pause indicator will be
on. Pressing [START/CONT] will continue the
scan from a paused state.
RESRV • INPUT
If the analog signal amplifier overloads before the
phase sensitive detector, then RESRV or INPUT is
displayed.
RESRV indicates that the signal amplifier is over-
loaded. Change the sensitivity or increase the
dynamic reserve.
INPUT indicates that the actual signal input is
overloaded. This occurs for voltage inputs greater
than 1.4Vpk (unless removed by AC coupling) or
current inputs greater than 10 µA DC or 1.4 µA AC
(1MΩ gain) or 100 nA DC or 14 nA AC (100MΩ
gain). Reduce the input signal level.
FILTR
If an overload occurs in the low pass filters after
the PSD's, then FILTR is displayed. Increase the
time constant or filter roll-off or decrease the
dynamic reserve.
OUTPT
If the output (either X, Y, R or a trace output volt-
age) is greater than 1.09 times full scale, then
OUTPT is displayed. This can occur if the sensitiv-
ity is too low or if the output is expanded such that
the output voltage exceeds 10 V. Note that a trace
output can overload even if it is not being dis-
played on the screen or output to CH1 or CH2.
Intrnl • Sweep • Ext S • Ext + • Ext -
If the internal reference is being used, then Intrnl is
displayed. If the internal reference frequency is
being swept, then Sweep is displayed. When
using an external reference source, the reference
mode may be set to Sine (Ext S), Rising TTL edge
(Ext +), or Falling TTL edge (Ext -).
LOCK • UNLOCK
The UNLOCK indicator turns on if the SR850 can
not lock to the external reference. LOCK is dis-
played when the SR850 is successfully locked to
the reference. LOCK is always on when in internal
reference mode.
Fr= XX.YYY Hz
The reference frequency (internal or external) is
displayed continuously.
Harmonic = N
The SR850 can detect synchronous signals at N
times the reference frequency. Generally, N is
equal to 1.
GPIB • RS232
Flashes when there is activity on the computer
interfaces. This does not flash for printer or plotter
activity.
ERR
Flashes whenever there is a computer interface
error such as an illegal command or out of range
parameter is received. This does not flash for a
printer or plotter error.
LOC • REM
REM is on when the front panel is locked out by a
computer interface. No front panel adjustments
may be made. To return the unit to local control (if
GPIB
Fr= 100.00 HzExt S
SRQ
Harmonic= 1
LOC
TRIG
Screen Display