This app uses the mobile phone’s microphone to listen to a sound at high frequencies, which are being emitted by an existing machine, based on binary pulses.
This application must:
- Receive the binary signal which is being emitted
- Display a decimal number as a result and refresh the result every 2 seconds
- indicate when it refreshes
- indicate: “no sound” if it does not hear anything
- indicate “interference” if other sounds in the frequency band 20 – 22k are present but do not conform to the structure of the expected signal.
The app MUST be designed on all of:
- Blackberry OS6/7
- Android
- iPhones
GUI
The design is not necessary, it can display basic text, black on white.
Binary Sound Key
Each “pulse” = 0.05s duration. A string will be up to 0.25seconds duration (consisting of up to 5 pulses), allowing a string to be repeated up to 4 times each second.
Code is basic binary with 4 bits:
Decimal Binary
0 0
1 1
2 10
3 11
4 100
5 101
6 110
7 111
8 1000
9 1001
The sound emitted from the machine will be:
20000Hz = 0
21000Hz = 1
21500Hz = gap
22000Hz = next string
Example string:
21000Hz for 0.05 seconds
20000Hz for 0.05 seconds
20000Hz for 0.05 seconds
21000Hz for 0.05 seconds
21500Hz for 0.05 seconds
21000Hz for 0.05 seconds
20000Hz for 0.05 seconds
21000Hz for 0.05 seconds
22000Hz for 0.05 seconds
this string is repeated forever
App must decode this and display in decimal:
1 0 0 1 = 9
gap
1 0 1 = 5
next
result to display = 95