SPECTRUM is designed for post-run (rather than real-time) processing of "spectral" or time- series data (y values at equally-spaced x intervals), such as spectra, chromatograms, electrochemical signals, etc. The program enhances the information content of instrument signals, for example by reducing noise, improving resolution, compensating for instrumental artifacts, testing hypotheses, and decomposing a complex signal into its component parts.

*SPECTRUM was the winner of two EDUCOM/NCRIPTAL
national software awards in 1990, for Best Chemistry
software and for Best Design*.

- Reads one- or two- column (y-only or x-y) text data tables with either tab or space separators.
- Displays fast, labeled plots in standard resizable windows with full x- and y-axis scale expansion and a mouse- controlled measurement cursor.
- Addition, subtraction, multiplication, and division of two signals.
- Two kinds of smoothing.
- Three kinds of differentiation.
- Integration.
- Resolution enhancement.
- Interpolation
- Fused peak area measurement by perpendicular drop or tangent skim methods, with mouse-controlled setting of start and stop points.
- Fourier transformation
- Power spectra
- Fourier filtering
- Convolution and deconvolution
- Cross- and auto-correlation
- Built-in signal simulator with Gaussian and Lorentzian bands, sine wave and normally-distributed random noise.
- A host of other useful functions, including: inspect and edit points, normalize, histogram, interpolate, zero fill, group points by 2s, bridge segment, superimpose, extract subset of points, concatenate, reverse X-axis, rotate, set X axis values, reciprocal, log, ln, antilog, antiln, standard deviation, absolute value, square root.

**Machine Requirements:** SPECTRUM runs only on older
Macintosh models running OS 7 or 8, minimum 1 MByte RAM, any
standard printer. Color screen desirable. SPECTRUM has been tested
on most Macintosh models and on all versions of the operating
system through OS 8.1. No PC version or more recent Mac version is
available or planned, but if you have some older model Macs laying
around, you might find this program useful. SPECTRUM was written
in Borland's Turbo Pascal in 1989. That firm has long been out of
business, neither the Turbo Pascal compiler nor the executable
code generated by that compiler runs on current Macs, and
therefore there is no way for me to update SPECTRUM without
completely re-writing it in another language.

SPECTRUM also runs on Windows 7 PCs using the Executor emulator, which since 2008 has been made available as open source software.

**The full version of SPECTRUM 1.1 is available as freeware, **and can be downloaded from http://terpconnect.umd.edu/~toh/spectrum/. There are two versions:

**SPECTRUM 1.1e**: Signals are stored internally as *extended-precision*
real variables and there is a limit of 1024 points per signal.
This version performs all its calculations in extended precision
and thus has the best dynamic range and the smallest numeric
round-off errors. The download address of this version in HQX
format is http://terpconnect.umd.edu/~toh/spectrum/SPECTRUM11e.hqx.

**SPECTRUM 1.1b**: Signals are stored internally as *single-precision*
real variables and there is a limit of 4000 points per signal.
This version is less precise in its calculations (has more
numerical round-off error) than the other version, but allows
signals with data more points. The download address of this
version in HQX format is http://terpconnect.umd.edu/~toh/spectrum/SPECTRUM11b.hqx.

The two versions are otherwise identical.

There is also a documentation package (located at http://terpconnect.umd.edu/~toh/spectrum/SPECTRUMdemo.hqx) consisting of:

**1. Reference manual.** MacWrite format (Can be opened from
within MacWrite, Microsoft Word, ClarisWorks, WriteNow, and most
other full-featured Macintosh word processors). Explains each
menu selection and describes the algorithms and mathematical
formulae for each operation. The SPECTRUM Reference Manual is
also available separately in in HTML
and PDF
format .

**2. Signal processing tutorial.** MacWrite format (Can be
opened from within MacWrite, Microsoft Word, ClarisWorks,
WriteNow, and most other full-featured Macintosh word
processors). Self-guided tutorial on the applications of signal
processing in analytical chemistry. This tutorial is also
available on the Web at
(http://terpconnect.umd.edu/~toh/Chem498C/SignalProcessing.html)

**3. Tutorial signals:** A library of prerecorded data files
for use with the signal processing tutorial. These are plain
decimal ASCII (tab-delimited) data files.

(c) 1989 T. C. O'Haver. This program is free and may be freely distributed. It may be included on CD-ROM collections or other archives.

T. C. O'Haver

http://terpconnect.umd.edu/~toh/

Polish translation of this page by Valeria Aleksandrova.

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Last updated March, 2015.

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