That is the newest program I wrote. Sonar uses the sound system of the mobile phone to generate echo maps. Three different modes are available: linear mode, angular mode and graph mode with averaged signal. I tested the program up to 50 miters and I must say, it is very stable. In the hart of the program is an autocorelation function responsible for high sensitivity. More technical details can be found here. Sonar can not work properly with phones equipped with the second microphone for the noise reduction.
- working frequencies 20Hz-20kHz but the real values strongly depend on the sound system an the speaker performance
- probing rate 48000 samples/s
- 16 bytes sound
- To improve sensitivity by factor 100, cut the plastic bottle top and use it as an „ear”