Rob,
I don't get why the time response will be more favourable for Goertzel's algorithm... The maximum time required for measuring the frequency would be the duration of one cycle of the lowest frequency, that is 1 KHz... So, even if we take 3-5 samples to get a good average and check for noise, the response time will be only about 5 millisec.

Why you use a costlier DSProcessor (8051 and DSP is not such a fast combination) when a simple 8051 would be more than sufficient for the job?

kundi