Working of a Wireless Mouse and Keyboard
Wireless keyboards and mice capture physical inputs and transmit them to a computer using radio waves, bypassing the need for physical cables.
The Transmission Process
- Input Detection: When you press a key, click a mouse button, or move the device across a desk, an internal microcontroller registers the electrical change and converts it into a digital data packet.
- Broadcasting: A built-in radio transmitter encrypts and sends this data over the airwaves. Modern peripherals almost exclusively use the 2.4 GHz frequency band to broadcast.
- Reception: A receiver picks up the signal. This is either a dedicated USB dongle plugged directly into the computer or the computer’s internal Bluetooth antenna.
- Processing: The receiver decrypts the radio signal and translates it back into standard Human Interface Device (HID) instructions. The operating system processes these instructions identically to a wired connection, registering the keystroke or cursor movement on screen in milliseconds.
Primary Wireless Technologies
| Feature | 2.4 GHz RF (USB Dongle) | Bluetooth |
| Receiver | Requires a dedicated proprietary USB dongle. | Connects directly to the device’s built-in Bluetooth. |
| Latency | Extremely low (often <1ms), making it ideal for gaming. | Slightly higher, though negligible for standard office work. |
| Multi-Device | Typically locked to its specific paired dongle. | Can pair with and quickly switch between multiple devices (PC, tablet, phone). |
| Power Draw | Highly efficient, often lasting years on a single battery. | Slightly higher power consumption than standard RF. |
The devices which I have uses a USB dongle as you have seen. Wanted to know if I can detect the 2.4 GHz signals with my RTL-SDR Blog V4. This is the answer which I got: “No, the RTL-SDR Blog V4 cannot directly pick up 2.4 GHz signals out of the box because its hardware tuning range is limited to 500 kHz up to 1.766 GHz”. I will need a microwave downconverter for that!