Stanford Research Systems SR844 User Manual page 94

3-36 Scan - Rel
Completing the scan parameter setup procedure does not start a scan. The frequency
reference remains unchanged (Internal or External reference mode) after all scan
parameters have been set.
Start/Step
This key is used to step through the scan frequencies. If no scan has been setup, the
factory preset values are used, namely Start = 100 kHz, Stop = 100 MHz, N = 4, which
gives interpolated frequencies of 1 MHz and 10 MHz.
The SR844 must be in Internal Reference mode to perform a scan. Start/Step has no
effect unless the unit is in Internal Reference mode.
Successive presses of Start/Step perform the following functions.
Keypress
1st
2nd ... Nth
N+1st
N+2nd
Important!
During a frequency scan, changing some front panel parameters will exit Scan Mode.
These are (1) changing the internal frequency and (2) switching to External Reference
mode.
OFF
This key sequence terminates Scan Mode. The SCAN MODE and SCAN DONE
indicators are turned off. It has no effect if SCAN MODE is off.
[Shift–
Scan Set]
Storing and Using Rel Values
This section discusses the storage of Rel Values at the scan frequencies. The Scan and Rel features work
together in a straightforward manner. First, use the Scan keys to specify the frequency scan (Start, Stop
and N) as described previously. Then, use Start/Step to step through the scan frequencies while using the
Store keys to store Rel Configurations and Values at each frequency. Changing scan parameters clears all
stored Rels.
XY Rel Values are actually stored X and Y offsets. R
stored settings of the reference phase. Rel Values are stored along with the current measurement
configuration. This is because offsets are generally valid only for a specific configuration and are not
SR844 RF Lock-In Amplifier
number of interpolated points is N – 2 .
Description
If a scan is not in progress, pressing the Start/Step key will begin one, if
the SR844 is in Internal reference mode. The frequency is set to the Start
frequency, F , and the SCAN MODE indicator is turned on.
start
Subsequent keypresses step to the next scan frequency, F
frequency reaches the Stop frequency, F
turns on.
Another keypress exits the Scan Mode while remaining at the Stop
frequency. The SCAN MODE and SCAN DONE indicators both turn
off.
The next keypress begins another scan, just like the 1st keypress above.
θ
Rel Values are stored offsets for R[dBm] and
. When the
i
,the SCAN DONE indicator
stop