Stanford Research Systems SR844, User Manual

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Gain and Time Constant 4-13
SR844 RF Lock-In Amplifier
Gain and Time Constant Commands
SENS (?) {i}
The
SENS
command sets or queries the Sensitivity. The parameter
i
selects a
sensitivity from the table below.
i Sensitivity i Sensitivity
0 100 nVrms / -127 dBm 8 1 mVrms / -47 dBm
1 300 nVrms / -117 dBm 9 3 mVrms / -37 dBm
2 1
µ
Vrms / -107 dBm 10 10 mVrms / -27 dBm
3 3
µ
Vrms / -97 dBm 11 30 mVrms / -17 dBm
4 10
µ
Vrms / -87 dBm 12 100 mVrms / -7 dBm
5 30
µ
Vrms / -77 dBm 13 300 mVrms / +3 dBm
6 100
µ
Vrms / -67 dBm 14 1 Vrms / +13 dBm
7 300
µ
Vrms / -57 dBm
AGAN
The
AGAN
command performs the Auto Sensitivity function. This command is the
same as pressing Shift–SensUp .
AGAN
automatically sets the Sensitivity of the
instrument.
This function may take some time if the time constant is long. This function does
nothing if the time constant is greater than 1 s. Check the Interface Ready bit (bit
1) in the Serial Poll Status to determine when the command is finished.
CRSV(?){i}
The
CRSV
command sets or queries the Close Dynamic Reserve Mode. The
parameter
i
selects High Reserve (
i=0
), Normal (
i=1
), or Low Noise (minimum
close reserve) (
i=2
).
ACRS
The
ACRS
command performs the Auto Close Reserve function. This command is
the same as pressing Shift–CloseResrv .
OFLT(?){i}
The
OFLT
command sets or queries the time constant. The parameter
i
selects a
time constant below.
i time constant i time constant
0 100
µ
s 9 3 s
1 300
µ
s 10 10 s
2 1 ms 11 30 s
3 3 ms 12 100 s
4 10 ms 13 300 s
5 30 ms 14 1 ks
6 100 ms 15 3 ks
7 300 ms 16 10 ks
8 1 s 17 30 ks
OFSL(?){i}
The
OFSL
command sets or queries the Time Constant Filter Slope. The
parameter
i
selects 6 dB/oct (
i=1
), 12dB/oct (
i=2
), 18dB/oct (
i=3
), or
24 dB/oct (
i=4
). This command also sets the No Filter mode, with parameter
i=0.