3 Short-Range Comms & IoT Mode
3.2 Modulation Analysis Measurement
The following parameters affect measurement speed when using adaptive
equalization:
meas interval
filter length (for the equalization filter)
points/symbol
Remote
Command
[:SENSe]:EVM:EQUalization:STATe OFF | ON | 0 | 1
[:SENSe]:EVM:EQUalization:STATe?
Example
:EVM:EQU:STAT ON
:EVM:EQU:STAT?
Preset OFF
State Saved Yes
Filter Length
This control enables you to set the length (in symbols) for the analyzer's equalization
filter.
In general, the best filter length is the smallest that meets your measurement
requirements. For measurements at the transmitter, the filter length may only need
to be a few symbols in length. Longer filter lengths may be needed to measure
multi-path environments.
The filter length also determines the placement of the impulse response in the
equalization filter. For longer filter lengths, the analyzer puts the initial, unit impulse
response closer to the beginning of the time record to accommodate multi-path
measurements, as follows:
Filter Length Unit Impulse Response Position
(symbol) (symbol)
3 to 31 (length - 1)/2
31 to 75 15
75 to 99 (length)/5
For example, if the filter length is 11, the unit impulse response is positioned at
symbol 5. If the filter length is 35, the unit impulse response is positioned at symbol
15.
Remote
Command
[:SENSe]:EVM:EQUalization:FLENgth <integer>
[:SENSe]:EVM:EQUalization:FLENgth?
Example
:EVM:EQU:FLEN 21
:EVM:EQU:FLEN?
Short Range Comms & IoT Mode User's &Programmer's Reference 281
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