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AMPTD Y Scale
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Offsets are used when gain or loss occurs between a device under test and the analyzer input. Thus, the
signal level measured by the analyzer may be thought of as the level at the input of an external amplitude
conversion device. Entering an offset does not affect the trace position or attenuation value, just the value
of the top line of the display and the values represented by the trace data. Thus, the values of exported
trace data, queried trace data, marker amplitudes, trace data used in calculations such as N dB points,
trace math, peak threshold, and so forth, are all affected by Ref Level Offset.
NOTE Changing the offset causes the analyzer to immediately stop the current sweep and
prepare to begin a new sweep, but the data will not change until the trace data
updates, because the offset is applied to the data as it is taken. If a trace is exported
with a nonzero Ref Level Offset, the exported data will contain the trace data with
the offset applied.
The maximum reference level available is dependent on the reference level offset. That is, Ref Level -
Ref Level Offset must be in the range –170 to +30 dBm. For example, the reference level value range
can be initially set to values from –170 dBm to 30 dBm with no reference level offset. If the reference
level is first set to –20 dBm, then the reference level offset can be set to values of –150 to +50 dB.
If the reference level offset is first set to –30 dB, then the reference level can be set to values of –200
dBm to 0 dBm. In this case, the reference level is “clamped” at 0 dBm because the maximum limit of
+30 dBm is reached with a reference level setting of 0 dBm with an offset of –30 dB. If instead, the
reference level offset is first set to 30 dB, then the reference level can be set to values of –140 to +60
dBm.
Example: DISP:WIND:TRAC:Y:RLEV:OFFS 12.7
Sets the Ref Level Offset to 12.7 dB. The only valid suffix is dB. If no suffix
is sent, dB will be assumed.
Preset: 0 dBm
State Saved: Saved in instrument state
Min: The range for Ref Lvl Offset is variable. It is limited to values that keep the
reference level within the range of –327.6 dB to 327.6 dB.
Max: 327.6 dB
Backwards Compatibility Notes: 1. In pre-X-Series instruments, Ref Level Offset could not be adjusted by the
knob or step keys. That is no longer the case.
2. In ESA and PSA, Ref Level Offset was applied to the data as it was
acquired; thus if the Offset changed the new offset was not applied until
new trace data was taken. In X-Series, the offset is applied as the data is
displayed/queried, so if you change the offset, it will change the data
immediately.
Initial S/W Revision: Prior to A.02.00
Modified at S/W Revision: A.04.00