- Name: Tchibo Funk-Wetterstation
- Model: 287717
- Frequency (indicated): 434 MHz
- Powered by two 1.5V AAA batteries
- Contains thermometer and hygrometer
Sensor transmits an OOK-modulated 1-second-long signal approximately once every 5 minutes on 433.85 MHz.
Recorded with gqrx via RTL2832U/R820T (433.79 MHz, AM):
After conversion to binary signal:
Signal has a pulse distance encoding.
Each transmission contains 6 repeats of the same message.
Each messages consists of 42 bits.
Low-bits have a pause length of approximately 1.5ms, high-bits 3.5ms:
Greatest common divisor:
We recorded a few transmissions (recordings/*.wav)
and compared the received data with the values indicated on the display (displayed-values.yml).
| bit range | carried information |
|---|---|
| 0-9 | constant, maybe sensor address? |
| 10-13 | unknown |
| 14-25 | temperature |
| 26-33 | relative humidity |
| 34-42 | probably checksum |
| bit index | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 |
|---|---|---|---|---|---|---|---|---|
| bit value | 8 | 4 | 2 | 1 | 128 | 64 | 32 | 16 |
Provides the relative humidity in percent.
| bit index | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| bit value | 8 | 4 | 2 | 1 | 128 | 64 | 32 | 16 | 2048 | 1024 | 512 | 256 |
Linear regression model estimates
temperature_celsius = temperature_index * 0.055601938800118336 - 67.83753671810342.