RESAM

Version:

1.1, November 1991

Hardware / OS requirements:

Low Level SESAM Workstation

Description:

• The RESAM software package contains a program for changing sample rates of signal files, RESAMP, and a program for adding two signal files, ADD.

• The RESAMP program changes a signal's sample rate from a sample frequency Fa to a sample frequency Fb by up-sampling from Fa to the least common multiple of both Fa and Fb, and subsequently down-sampling to Fb. When up-sampling a signal k times, each sample is multiplied by adding (k-1) zeros. The up-sampled signal is interpolated using a low-pass filter and down-sampled m times by extracting each m-th sample.

• For example, when resampling noise signals (derived from Noise-Rom 0) from 20 kHz (up 4 times, down 5 times) into 16 Khz (Eurom 0 standard), a lowpass fir filter with a cutoff frequency of 16/2=8 Khz at a sample rate of 20*4=80 Khz has been defined (0.1 fs).

• Resampling a signal from 20 kHz into 16 kHz using the 1024 taps FIR filter will take about one hour per megabyte on a 286-12 mHz with co-processor. A program for designing `windowed FIR filters' named WFIRDESN is also supplied. More details on the use of these programs can be found in the readme file on the distribution diskette.

• The program ADD allows to add signals with a specified gain factor and an offset value, which both can be determined with the SLM program. Also for the first signal, a time-offset measured in samples can be specified. This feature allows for a random start point in the noise files.

• Each i-th output-sample is calculated according to the following expression: Out[i] = Gain0 * (Input0[i + SampleOffset0] - Offset0) + Gain1 * (Input1[i] - Offset1) No indication is given if the 16 bits dynamic range is exceeded.

Developing lab:

TNO Institute for Perception
P.O. Box 23
3769 ZG Soesterberg
Netherlands

Tel: (31) 34 63 56 230

Fax: (31) 34 63 53 977

Contact:

Jan A. Verhave