In fact, direction finding has little to do with synthetic aperture radar, but I still plan to write an article in this collection. One is because if direction finding and ranging are combined, objects can be accurately positioned and images similar to point clouds can be obtained. The other is that whether it is radio waves or sound waves, the ranging and direction finding algorithms are relatively close, but the ranging is in Comparing the difference between sending and receiving, the direction finding is comparing the difference between the two receiving channels. Finally, the radio compass and microphone array I made before are relatively complicated. This time, the radio wave direction finding and sound wave direction finding realized by gnuradio simple flow diagram are actually the basis of the radio compass and microphone array. If you are interested, this article Articles are a great place to start.
First post a flow diagram of the radio direction finding.
There are a few points to note:
1. The dual-channel LimeSDR-USB must be used, and the LimeSDR Mini cannot be used, because the phase difference between the two receiving channels must be obtained.
2. Since the phase difference direction finding is used, the received signal must be narrowband. You can use PortaPack to transmit an FM modulated Sine wave. Although it is not exactly the same as the single tone, it is also narrowband, and you can still use this stream Figure direction finding.
Paste a sound wave direction finding flow diagram again
The things to note with this flow graph are:
1. You need to make sure that your computer's microphone is stereo, if it is mono, it cannot be used.
2. You need to find the position of these two microphones, preferably in a straight line, neither too close nor too far away, if it is too close, you cannot distinguish the difference in sound wave transmission time, if it is too far away, you will not be able to connect the two microphones It is approximated as a particle, so that it is impossible to move the sound source so that it has only angular changes relative to the microphone and no radial changes.
3. Sound source It is recommended that you play a rock music on your mobile phone, and point the speaker of the mobile phone at the computer microphone at all times to make good use of its directionality.
video:
Gnuradio implements radio direction finding and acoustic direction finding_哔哩哔哩_bilibili
netdisc:
Link: https://pan.baidu.com/s/1yHXlWSOwNrwUe-eFc4hvAA Extraction code: piks