PDF Papers and App Notes

The following documents from the SR Library may be of interest.
Some review topics of general interest, while others discuss specific SR equipment.

Scaling and Biasing Analog Signals

This paper describes techniques for interfacing electronic equipment with different input and output voltage ranges together. Theory and circuits for changing the range and offset of analog signals is reviewed, including passive 2 and 3 resistor designs as well as basic op amp techniques.

These techniques are useful in real life for interfacing sensors with one voltage range to data acquisition equipment with a different range. While not particularly difficult, the theory for many of the circuits is interesting. Subjects like scaling and projective transforms even prove to be useful.

Precision sine waves with the DSP32C

A precision sine wave generator program suitable for use with D/A converters hooked up to a DSP32C digital signal processor is reviewed. While simple in principle, precision sine wave generation requires careful programming.

Low precision methods for generating a sine wave include table look up, interpolation, and incremental methods based on the addition formulas for sine and cosine. But these result in tables of considerable size, interpolation noise, or accumulated incremental error. Better solutions are discussed.

FFT routines in C

This zip file contains a sequence of programs developing code for the Fast Fourier Transform ( FFT ). The programs proceed from a simple recursive FFT function, onward to a production level radix 2 algorithm. All examples are in standard C source code.

Customers are welcome to use these routines for custom programing in their applications. Executables are for standard x86/DOS architectures. Recompiling for other platforms is straighforward. The final radix 2 FFT does not use any C runtime library functions, but does expect floating point arithmetic to be available.

See the readme.txt file for a description of the algorithms covered.

Additional Papers

The following additional papers may be requested by email at info@symres.com.

Requests coming from countries or individuals know for plagiarism or disregard of copyright will be ignored.

Using a Meinberg DCF Radio Clock w/ USBxCH 2014/01/22 1,152,179 bytes PDF

Describes the steps required to configure and connect a Meinberg C600RS DCF77 radio clock so it can provide accurate time stamp information to SR USBxCH data acqusition systems.

Analog Response of Sigma Delta Converters 2003/07/19 319,836 bytes PDF

Describes the analog filter response of the Burr-Brown ADS1210 chip used on SR PARxCH data acquisition systems. The ADS1210 is a second-order sigma-delta A/D converter incorporating a three-stage low-pass filter which defines the analog system response.