Money item acceptor

1. A method of accepting money items, comprising:

providing sensor circuitry for generating money items signals that are a function of money items under test;

providing a processor for developing an acceptability criterion dependent on a fraud attack, and

developing for each of the money items under test, a transformed money item signal that is a function of the money item signal and at least one variable parameter that is a function of the fraud attack acceptability criterion and determined in response to the fraud attack while the fraud attack is occurring;

providing a memory for storing window limit values;

said processor making a comparison of the transformed money item signals with a window limit value; and

providing a gate for accepting or rejecting each money item based on the comparison.

2. The method according to claim 1 wherein the at least one variable parameter is a function of history data relating to the money item signals for previously tested money items.

3. The method according to claim 1 further comprising comparing an average of data corresponding to the money item signals for previously tested money items with a first limit value lying within a window delimited by the window limit value, and if the average is not within the first limit, scaling the money item signal with an amplification factor.

4. The method according to claim 1 further comprising comparing a maximum value of data corresponding to the values of money item signals for previously tested money items with a second limit value lying within a window delimited by the window limit value, and if the maximum value is not within the second limit, scaling the money item signal with an amplification factor.

5. The method according to claim 1 wherein the window limit has a fixed value.

6. The method according to claim 1 wherein the window limit value delimits a window as deviation relative to a window mean, and including revaluing the money item signal relative to the window mean, whereby to produce re-value money item data and developing the transformed money item signal from the re-valued money item data.

7. The method according to claim 1 performed in a coin acceptor, and including varying the transformation of the money item signals in dependence on data received from an external source to the coin acceptor.

8. The method according to claim 7 wherein the data received from the external source comprises data indicative that of a fraud attack on other acceptors.

9. The method according to claim 1 wherein the money items comprise coins or tokens.

10. An acceptor for money items, comprising:

sensor circuitry to provide money items signals as a function of money items under test, and

a processor configuration

to develop an acceptability criterion dependent on a fraud attack,

to develop for each of the money items under test, a transformed money item signal that is a function of the money item signal and at least one variable parameter that is a function of fraud attack acceptability criterion and determined in response to the fraud attack while the fraud attack is occurring,

to make a comparison of the values of the transformed money item signals with a window limit value, and

to accept or reject each money item based on the comparison.

11. The acceptor for money items according to claim 10 wherein the at least one variable parameter is a function of history data relating to the values of the money item signals for previously tested money items.

12. The acceptor for money items according to claim 10 wherein the processor configuration is operable to compare an average of data corresponding to the money item signals for previously tested money items with a first limit value lying within a window delimited by the window limit value, and if the average is not within the first limit, to scale the money item signal based on the amplification factor.

13. The acceptor for money items according to claim 10 wherein the processor configuration is operable to compare a maximum value of data corresponding to the values of money item signals for previously tested money items with a second limit value lying within a window delimited by the window limit value, and if the maximum value is not within the second limit, to scale the money item signal based on the amplification factor.

14. The acceptor for money items according to claim 10 wherein the window limit has a fixed value.

15. The acceptor for money items according to claim 10 wherein the window limit delimits a window as deviation relative to a window mean, and the processor configuration is operable to re-value the value of a money item signal for a money item relative to the window mean, whereby to produce re-value money item data, and to develop the transformed money item signal from the re-valued money item data.

16. The acceptor for money items according to claim 10 wherein the processor configuration is operable to control the transformation of the money item signals in dependence on data received from an external source.

17. The acceptor for money items according to claim 16 wherein the data received from the external source comprises data indicative of a fraud attack on other acceptors.

18. The acceptor for money items according to claim 10 operable to accept coins or tokens.

19. The acceptor for money items according to claim 10 , wherein the acceptor is a multi-denomination.