Chapter 4 179
Downloading and Using Files
Downloading FIR Filter Coefficients
Downloading FIR Filter Coefficients
The signal generator accepts finite impulse response (FIR) filter coefficient downloads. After downloading
the coefficients, these user-defined FIR filter coefficient values can be selected as the filtering mechanism
for the active digital communications standard.
Data Requirements and Limitations
• Data must be in ASCII format. The signal generator processes FIR filter coefficients as floating point
numbers.
• Data must be in List format. FIR filter coefficient data is processed as a list by the signal generator’s
firmware. See “Sample Command Line” on page 184.
• Filters containing more symbols than the hardware allows are not selectable for that configuration.
The Real Time I/Q Baseband FIR filter files are limited to 1024 taps (coefficients), 64 symbols, and a
16-times oversample ratio. FIR filter files with more than 64 symbols cannot be used.
The ARB Waveform Generator FIR filter files are limited to 512 taps and 512 symbols.
• The oversample ratio (OSR) is the number of filter taps per symbol. Oversample ratios from 1 through
32 are possible. The maximum combination of OSR and symbols allowed is 32 symbols with an OSR of
32.
• The sampling period (∆t) is equal to the inverse of the sampling rate (FS). The sampling rate is equal to
the symbol rate multiplied by the oversample ratio. For example, for a symbol rate of 270.83 ksps, if the
oversample ratio is 4, the sampling rate is 1083.32 kHz and ∆t (inverse of FS) is 923.088 ns.
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