Stanford Research Systems SR844 User Manual page 93

Use the Rel Mode key to toggle REL MODE on and off.
In SCAN MODE with REL MODE on, the instrument automatically recalls the stored Rel Configuration
and Rel Values at each scan frequency. The REL indicator within the CH1 and CH2 displays is on
whenever the recalled Rel Configuration and Rel Values are in effect.
If the current scan frequency does not have any stored Rel Values (as indicated by XY READY or
θ θ θ θ )
R[dBm] , the current configuration and offsets remain in effect. The REL indicator is off in this case.
The stored XY Rel Values are applied as X and Y offsets (adjusted for the current phase). The stored
R[dBm] Rel Value is applied as the R[dBm] offset. The stored
Phase (there is no phase offset). Offset indicators within the CH1 and CH2 displays are turned on as
appropriate (as well as the REL indicator).
After the Rel Configuration and Rel Values are recalled, the instrument setup can be modified using the
front panel or remote interface. Once the configuration is modified, the REL indicator turns off indicating
that the current configuration is not the recalled Rel Configuration. Toggle REL MODE off and back on to
recall the stored Rel Configuration once again.
When REL MODE is off, stored Rel Configurations and Rel Values are ignored (the configuration and
offsets currently in effect are still applied to the measurement).
Use the CLEAR ALL key (Shift–Rel Mode) to clear all stored Rel Configurations and Values and
CLEAR ONE (Shift–Start/Step) to clear the Rels at the current scan frequency only.
Scan and Rel parameters are stored in non-volatile memory and recalled at power on. They are not stored
with the 9 available stored setups.
Using Frequency Scans
This section discusses the operation of the frequency Scan Mode. The Scan Mode can be used in
conjunction with Rel Mode as described in the following section.
Scan Set
This key accesses the scan frequency parameters. Successive keypresses are used to
cycle through the Start and Stop frequencies and Number of Points on the Reference
Display. The knob is used at each stage to modify the current parameter.
Changing the scan parameters is not permitted if a scan is in progress (SCAN MODE
indicator on). In such a case the knob has no effect. There are three scan parameters:
Parameter Description
Start
Stop
Number of
Points
The start frequency, F
start
the START indicator within the display. Use the knob to select a start
frequency in the range 25 kHz – 200 MHz.
The stop frequency F
stop
the STOP indicator within the display. Use the knob to select a stop
frequency in the range 25 kHz – 200 MHz.
The number of points, N, is shown on the Reference Display. There is no
indicator shown in the display. Use the knob to select from 2 to 11 steps.
The number of points includes both the start and stop frequencies, so the
θ
Rel Value is applied as the Reference
, is shown on the Reference Display, along with
, is shown on the Reference Display, along with
SR844 RF Lock-In Amplifier
Scan - Rel 3-35