GALOIS is a program to generate pseudorandom signals based on maximum-length sequences in finite fields. The signals can be designed to have desirable properties for dynamic system testing. All signal designs are accomplished in stages, at each of which the user can specify parameters that confer the required signal properties. At any stage of a signal design, the graphical user interface of the program allows experienced users to input the parameters they require, while inexperienced users are also able to examine the underlying basis for the stage with the assistance of an extensive help facility that is available in all windows.

In first design stage, the finite field for the maximum-length sequence is selected. The number of field elements determines the greatest number of levels that the resulting pseudorandom signal can have. The user may specify any prime or extension field, and then inspect the sum and product tables on which operations in the chosen field are based.

In the second design stage, the primitive polynomial in the field that is to be used as the characteristic polynomial of the maximum-length sequence is selected. The degree of the polynomial determines the period of the maximum-length sequence and the pseudorandom signal based on it. The user may inspect every primitive polynomial of a specified degree in the field before making a selection.

In the third design stage, the maximum-length sequence is generated. The user may inspect a period or a subperiod of the characteristic phase of the sequence.

In the final design stage, the field elements are converted into the pseudorandom signal levels. The user may either exercise a free choice or use pre-determined conversions that confer specific properties on the pseudorandom signal. Conversions have been developed to generate pseudorandom signals with specified harmonics suppressed, with primitive autocorrelation functions or with minimum crest factors. The user may inspect a period or subperiod of the pseudorandom signal before filing it for use with other software packages.

GALOIS is made freely available on this website by permission of Professor H.A.Barker of the University of Wales, Swansea. If it is used to obtain results that are subsequently published, then this website should be quoted as the source and an appropriate acknowledgement made.

GALOIS will run on PCs with Windows 95, 98, 2000, NT, XP or Vista.
It requires a screen area of 1024 by 768 pixels and small fonts.

To install GALOIS, click here to download the program as a Zip file.
In the File Download window, click Open. In the Zip window, click Install.
In the Install window, click OK. Throughout the Galois Setup Program, click Next to continue.
In the Setup Complete window, click Finish.

To run GALOIS, either click Start > Programs > Galois > Galois Icon
or click Start > Programs > Galois > Galois Icon > right click > Create Shortcut, then move the Galois Icon to the desktop and subsequently double click it.

In the event of a problem, email  H.A.Barker @ swansea.ac.uk