Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide 361
Creating and Downloading User–Data Files
FIR Filter Coefficient Downloads
The sampling period (Δt) is equal to the inverse of the sampling rate (FS). For
modulation filters, the sampling rate is equal to the symbol rate multiplied by
the oversample ratio. For example, the GSM symbol rate is 270.83 ksps. With
an oversample ratio of 4, the sampling rate is 1083.32 kHz and Δt (inverse of
FS) is 923.088 nsec.
Downloading FIR Filter Coefficient Data
The signal generator stores the FIR files in the FIR (/USER/FIR) directory, which
utilizes non–volatile memory (see also “Signal Generator Memory” on
page 321). Use the following SCPI command line to download FIR filter
coefficients (file) from the PC to the signal generator’s FIR directory:
:MEMory:DATA:FIR <"file_name">,[REAL,]osr,coefficient
:MEMory:DATA:FIR
<"file_name">,COMPlex,osr,realCoefficient,imaginaryCoeffic
ient,...
Use the following SCPI command line to query list data from the FIR file:
:MEMory:DATA:FIR? <"file_name">
Sample Command Line
The following SCPI command will download a typical set of real modulation FIR
filter coefficient values and name the file “FIR1”:
:MEMory:DATA:FIR
"FIR1",4,0,0,0,0,0,0.000001,0.000012,0.000132,0.001101,
0.006743,0.030588,0.103676,0.265790,0.523849,0.809508,1,1,0.
809508,0.523849,
Filter Type Oversampling Ratio
(OSR)
Number of Taps
(Maximum)
Symbols/Coefficients
(Maximum)
Equalization
a
a. When I/Q timing skew, I/Q delay, or the ACP internal I/Q channel
optimization features are active, the effective number of taps for the
equalization filter are reduced.
1256--
ARB Custom
Modulation
b
b. The filter may be sampled to a higher or lower OSR.
≥ 2 -- 512/1024
Dual ARB
Real-Time
Modulation
c
c. The filter will be decimated to a 16 or lower OSR depending on the
symbol rate.
≥ 2 -- 32/1024
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