Wi-Fi Coverage Mapping Robot for Your Home

Measuring at the same height and in a grid makes the results comparable. The robot carries the Pi's Wi-Fi radio along the grid, reads the signal from your router at each point and Python draws the map.

Mission steps

1. Mark a grid

   Put small tape marks on the floor every metre and note their x,y positions on a sketch of the room.

2. Drive the robot

   Use the gamepad robot setup to drive to each mark. Keep the Pi connected to your own home Wi-Fi.

3. Log the signal

   At each mark press a button; the script averages five readings of the link signal from iw and saves x, y and dBm to a CSV.

4. Draw the heatmap

   Plot the CSV with matplotlib; around −50 dBm is excellent, below −70 dBm is weak.

5. Act on it

   Move the router, change its antennas or add a mesh node, then map again to see the difference.

Code

import re, subprocess, time, csv

def rssi():
    out = subprocess.run(['iw', 'dev', 'wlan0', 'link'], capture_output=True, text=True).stdout
    m = re.search(r'signal:\s*(-?\d+)', out)
    return int(m.group(1)) if m else None

with open('wifi_map.csv', 'a', newline='') as f:
    w = csv.writer(f)
    while True:
        pos = input('Grid position x,y (blank to quit): ')
        if not pos: break
        x, y = map(float, pos.split(','))
        vals = []
        for _ in range(5):
            v = rssi()
            if v is not None: vals.append(v)
            time.sleep(1)
        avg = sum(vals) / len(vals)
        w.writerow([x, y, round(avg, 1)]); f.flush()
        print('Saved %.1f dBm at (%g, %g)' % (avg, x, y))

Tip: test every script on the bench before installing it in a moving machine.

Questions