Stimulus analysis system and method having adaptive artifact rejection
A stimulus analysis system and artifact rejection method are disclosed. The method may be used in many applications, such as, for example, DPOAE testing, TEOAE testing, BAER testing, ultrasound, MRI, RADAR, GPS, EEG, EKG, or communications. In one embodiment, a system receives a signal, and depending on the noise power of the signal, the signal is placed in one of a plurality of buffers or is discarded. This process is repeated. The combination of buffers that yields the lowest noise power is then selected. The selected combination of buffers may then be used to calculate a signal to noise ratio, which may be used to determine whether the signal received is acceptable, indicating, for example, that a test has been passed or failed.
1. A method of artifact rejection comprising:
(a) transmitting a stimulus;
(b) receiving a response to the stimulus;
(c) splitting the response into a noise component and a signal component;
(d) calculating a noise power from the noise component;
(e) based on the calculated noise power, storing the noise component in one of a plurality of noise buffers and the signal component in a corresponding one of a plurality of signal buffers;
(f) repeating steps (a) through (e);
(g) selecting a combination of the plurality of noise buffers to which noise components were stored in step (e), the selected combination of the plurality of noise buffers having a lowest noise power; and
(h) calculating a signal power from a combination of signal buffers corresponding to the selected combination of noise buffers.
2. The method of claim 1 further comprising counting the number of noise and signal components stored in each of the plurality of noise buffers and signal buffers, respectively.
3. The method of claim 1 further comprising:
calculating a signal power to noise ratio from the calculated signal and the lowest noise power; and
comparing the calculated signal to noise ratio to a predetermined value.
4. The method of claim 3 further comprising performing a function if the calculated signal to noise ratio is greater than the predetermined value.
5. The method of claim 3 further comprising performing a function if the calculated signal to noise ratio is less than the predetermined value.
6. The method of claim 1 wherein each stimulus comprises a plurality of points.
7. The method of claim 6 wherein each stimulus comprises 1024 points.
8. The method of claim 1 wherein each of the plurality of noise and signal buffers comprise eight buffers.
9. The method of claim 1 wherein the method is employed in one of a DPOAE test, a TEOAE test, a BAER test, an ultrasound operation, an MRI operation, a RADAR operation, a GPS operation, an EEG operation, an EKG operation, or a communications operation.
10. The method of claim 1 wherein splitting the response into a noise component and a signal component comprises taking the discrete Fourier transform of the response.
11. The method of claim 10 wherein seven different frequencies are employed.
12. The method of claim 1 further comprising discarding the response if the noise power of the noise component does not fit within an acceptable range of the plurality of noise buffers.
13. A method of artifact rejection comprising:
(a) transmitting a stimulus;
(b) receiving a response to the stimulus;
(c) calculating a noise power from the response;
(d) based on the calculated noise power, storing the response in one of a plurality of buffers;
(e) repeating steps (a) through (d);
(f) selecting a combination of the plurality of buffers to which responses were stored in step (d), the selected combination of the plurality of buffers having a lowest noise power; and
(g) calculating a signal power based on the selected combination of buffers.
14. The method of claim 13 further comprising counting the number of responses stored in each of the plurality of buffers.
15. The method of claim 13 further comprising:
calculating a signal power to noise ratio from the calculated signal and the lowest noise power; and
comparing the calculated signal to noise ratio to a predetermined value.
16. The method of claim 15 further comprising performing a function if the calculated signal to noise ratio is greater than the predetermined value.
17. The method of claim 15 further comprising performing a function if the calculated signal to noise ratio is less than the predetermined value.
18. The method of claim 13 further comprising discarding the response if its calculated noise power does not fall within one of a plurality of acceptable noise power ranges corresponding to respective ones of the plurality of buffers.