Neil Hopcroft

A digital misfit

Whats your favorite test tone generation algorithm?

I’m looking for a noise that can be programmatically generated, is fairly pleasant to listen to and is obvious if it isn’t correctly sequenced or if there are dropouts between buffers. This afternoons crude ‘top three bits of address in buffer’ algorithm generates a horrible jagged saw wave.

I don’t want to spend weeks coding it but also I want to use it for weeks of testing the digital part of an audio system, which means its got to be OK to listen to for that long. My current best hope is a sine wave of settable frequency allowing at least some expression to the tests. But maybe you can think of something better?


Categories: Memories.

/ 1 Comment

1 comment

  1. cabbage

    I’d be tempted to use a swept sine wave – assuming you have a sine function available – it is only the replacement of sine(t) with sine(t + a t^2) – assuming that your “t” is in appropriate units and “a” is a constant inversely proportional to the speed of the sweep – so that over a 5-10 second period you travel from 100Hz to 2kHz (say) – the timescale might depend on the likely period/length of out-of-order segments though.

    To make it less annoying you could narrow the range and stick to lower frequencies. You could also make the frequency modulation triangular so that it ramped down as well as up which might make it a little more relaxing – for a fast period of sweep this makes for a gentle warble.

    Reply

Leave a Reply

Your email address will not be published.