Specifications

Programming Guide 3-23

ESG Family Signal Generators Remote Data Transfer

FIR Filter Coefficient Data Downloads

Options UN8 and UND signal generators accept finite impulse response (FIR) filter

coefficient data downloads. After downloading the data, these user-defined FIR filter

coefficient values can be selected as the filtering mechanism for the active digital

communications standard.

This chapter contains information that will help you transfer user Finite Impulse

Response filter data from a system controller to your signal generator.

This section explains how to download user-defined FIR filter coefficient files into the

signal generator’s memory catalog and activate them. It is divided into the following

subsections:

Data Requirements

There are two requirements for FIR filter coefficient data downloads:

1. Data must be in ASCII format.

The signal generator processes FIR filter coefficients as floating point numbers.

2. 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 3-30.

Data Limitations

Filter lengths of up to 1024 taps are allowed. 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 signal generator’s hardware achieves the filtering through a combination of digital

and analog implementation.

Option UN8 is limited to 256 taps, 32 symbols and a 16-times oversample ratio. Therefore,

any number of taps you insert are digitally resampled into a maximum of 16-times

oversampling with 16 symbols, or a maximum 8-times oversampling with 32 symbols. FIR

filters more than 32 symbols long cannot be used.

Option UND is limited to 512 taps and 24 symbols.

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, the GSM

symbol rate is 270.83 ksps. With an oversample ratio of 4, the sampling rate is

1083.32 kHz and

∆t (inverse of Fs) is 923.088 nsec.