Welcome to the SEM escape lab
5th and last Key
Matching the waves
Find the coefficients and match the signal.
4 sinewaves are combined to build a signal:
- the frequency of the second one is the double of the first one's.
- the frequency of the third one is the double of the second one's.
- the frequency of the fourth one is the double of the third one's.
Each sinewave is damped by a power of 2 : in terms of hardware, the signal values are shifted to the right by a given number of bits. The damped sinewaves are then added together to form the signal at the bottom of the following picture.
Damping factors can either be 1, 1/2 and 1/256. The key is the modulo 30 sum of:
- the power of two of the first coefficient (0 for 1, 1 for 1/2 and 8 for 1/256)
- two times the power of two of the second coefficient
- three times the power of two of the third coefficient
- four times the power of two of the fourth coefficient
PS: 1st coefficient is 0