Introduction
LOOK is a program for digital signal analysis and graphical display. It also performs some digital signal processing functions and can save the results to a disk file. Input is from data files stored on disk or signals generated within the program.

Requirements
LOOK runs on PCs with Windows 95 and higher. It is not compatible with MAC or SUN computers.

Installation
LOOK does not need to be installed. Just put LOOK.EXE in whatever folder you wish and create a shortcut on the desktop.

License
LOOK software is copyright © 2005 by Cliff Leitch. It is free for personal or educational use. All other rights are reserved. LOOK is supplied to you on an "as is" basis, without warranty of any kind. Registration is not required.

Screenshots

Menu

Graph

Capability
LOOK can read time or frequency domain input signals from disk:

• Real time domain data
• Complex time domain data
• Real frequency domain data
• Complex frequency domain data

Or, LOOK can read two independent real or complex signals of any type.

Or, LOOK can generate real or complex signals from an arbitrary equation.

LOOK is intended for use with uniformly sampled data. That is, the sampling interval of the x axis (time, frequency or whatever) must be uniform throughout the data file. Non-uniformly sampled data is NOT supported except for the X-Y plot case.

The program can perform various signal processing operations:

• Fourier transforms and inverse Fourier transforms
• Windowing -- Cosine, Cosine-squared, Rectangular, Kaiser or notch.
• Linear transforms -- add a constant, multiply by a constant, multiply by a complex exponential or multiply by a sinusoid
• Filtering -- Chebyshev, Butterworth, Transitional, Bessel filter or arbitrary H(s) (Laplace transform). It will generate the filter functions and apply them to the input signal.
• Change sampling rate -- upsample and downsample
• Differentiation and integration
• Autocorrelation
• Convolution
• Crosscorrelation

It can also graph, list or save to file various parameters of the input signal(s):

• Real component
• Imaginary component
• Amplitude (absolute value)
• Power
• Phase
• Instantaneous frequency (FM demodulation)
• Group delay of filters
• Deviation from linear phase
• X-Y (Lissajous) graphs
• Product of real and imaginary parts
• Sum and difference of real and imaginary parts
• Linear regression lines

It also computes:

• Sliding window averages
• Probability distributions
• Cumulative distributions
• Various statistics such as rms, mean, min, max, etc.

All internal calculations are done with double precision complex arithmetic, which has a precision of about 16 significant figures (decimal).

Download
LOOK.ZIP contains the program and the instruction manual in pdf format.

Download LOOK.ZIP (362 KB)

Q & A

Q: Is LOOK free?
A: It is free for personal or educational use. All other rights are reserved.

Q: Is registration required?
A: No, you do not need to register.

Q: Is technical support available?
A: Unfortunately, no. However, you can use the Contact Form to send us bug reports or other comments.

Q: Is there a user forum?
A: No, but if someone wants to start one, I will post a link here.

Q: Where did LOOK come from?
A: LOOK was written and updated by the author over a period of 30 years for personal and professional use in the fields of digital signal processing and electrical engineering.

Q: Is LOOK compatible with other signal processing programs?
A: LOOK can read and write ASCII files for compatibility with spreadsheets and other applications. There are also MATLAB "m" files, Cread.m and Cwrite.m, which enable MATLAB to read and write files in native LOOK format.

Q: Does LOOK contain spyware or any other hidden programs?
A: No, absolutely not!

Q: What language is LOOK written in?
A: It is a 32-bit application written in Fortran 90. The graphics and some other functions are specific to the DEC/Compaq Visual Fortran compiler version 6.

Q: Is the source code available?
A: No, not at this time.

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