https://github.com/joelibaceta/wifi-tracing
A contact tracing hackaton idea
https://github.com/joelibaceta/wifi-tracing
Last synced: about 1 month ago
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A contact tracing hackaton idea
- Host: GitHub
- URL: https://github.com/joelibaceta/wifi-tracing
- Owner: joelibaceta
- License: gpl-3.0
- Created: 2020-07-26T03:38:59.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2022-12-10T10:02:39.000Z (over 2 years ago)
- Last Synced: 2025-05-03T05:46:10.428Z (about 1 month ago)
- Language: Java
- Size: 1.37 MB
- Stars: 17
- Watchers: 1
- Forks: 0
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
Inspired by [bluetrace](https://bluetrace.io/)
This alternative propose to use a mutiple wifi signal strength measurements to guess positions within a physical location.
Serve data with indoor x,y positions for contact tracing
This demo contains:
- An android and raspberry aplications as end user applications.
- A website to monitor the people position in a floorplan. (For demo purpose only)
- A backend where historical positioning data is stored
## How it works?
1. Get the distances from the main wifi points.
Python
```python
def scan(interface='wlan0'):
cmd = ["iwlist", interface, "scan"]
proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
points = proc.stdout.read().decode('utf-8')
return points
```
Android
```java
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);
registerReceiver(wifiScanReceiver, intentFilter);
wifiManager.startScan();
```
### Convert from dBm to meters in a simplified escenario
```python
def dbm2m(frequency, dBm):
FSPL = 27.55 #Free-Space Path Loss
m = 10 ** (( FSPL - (20 * log10(frequency)) + abs(dBm) ) / 20 )
return round(m, 2)
```
2. Use 2d trilateration algorithm to get x, y position estimation in the floorplan
Trilateration allow us to estimate position coordinates using distances from recerence points.
```javascript
A = 2*x2 - 2*x1
B = 2*y2 - 2*y1
C = r1**2 - r2**2 - x1**2 + x2**2 - y1**2 + y2**2
D = 2*x3 - 2*x2
E = 2*y3 - 2*y2
F = r2**2 - r3**2 - x2**2 + x3**2 - y2**2 + y3**2
x = (C*E - F*B) / (E*A - B*D)
y = (C*D - A*F) / (B*D - A*E)
```
3. Store position trought the time
Using mongodb as data wharehouse
## User interfaces alternatives
You can use it as an android application or with a raspberry in an IOT Context
## References
- [User Configurable Indoor
Positioning System using WiFi
Trilateration and Fingerprinting](https://www.diva-portal.org/smash/get/diva2:1105921/FULLTEXT02)
- [On Improved Projection Techniques to Support Visual Exploration of Multidimensional DataSets](http://repositorio.icmc.usp.br/bitstream/handle/RIICMC/6868/relatorio_207.pdf?sequence=1http://repositorio.icmc.usp.br/bitstream/handle/RIICMC/6868/relatorio_207.pdf?sequence=1)