Baby monitors are not secure communication devices. It is a crude radio transmitter.
It is located in the nursery. Transmits FM signals at a fixed frequency. When the unit is powered, it practically becomes a mini radio station. Most older models transmit certain channels in the 49 MHz range. The label may have 49.300 MHz, 49.830 MHz or 49.890 MHz. Some devices have an A/B switch that allows you to switch between two presets.
This is important because a simple radio scanner can easily pick up that transmission.
If your home does not have aluminum siding, the signal will leak. The bedroom on the second floor provides no shielding. The receiver of the handheld scanner is much more sensitive than the speakers on the monitor. It can catch audio from half a mile away. This includes all the cry, coo, and conversation.
The Hardware Problem
These frequencies are in a narrow band. They are just above the older analog cordless phones from the 1980s and 1990s. These are located directly below VHF TV Channel 2. This spectrum is so common that almost every electronics store has scanners that cover the 49-50 MHz range.
You don’t need military gear to listen. All you need is a regular scanner.
The Simple Fix
Turn it off.
This is obvious. However, most people leave the base station plugged in and the camera unit in standby mode. If you are not looking at the screen, you should turn the monitor off. This completely removes the signal. This is the only way to guarantee privacy in these older analog systems.
Technology reuse
Do not throw away the device, even if your child grows up and no longer needs constant supervision. It is also a useful tool for adults.
You can place the camera near the TV speakers. Then take the portable receiver to another room or garden. You hear the show without dragging a long cord. It also works with a remote doorbell. Or a buzzer in the garage.
Where do we go from here?
To understand the mechanism behind this vulnerability, take a look at how radio scanners work. The technique is simple. It is based on the basic principles of signal reception and frequency modulation.
For more technical details, see this resource on how the radio spectrum is allocated. Websites like Strong Signals offer comprehensive guides for scanner users. You can also read the Monitoring Times, a journal dedicated to radio enthusiasts. Understanding these basics will help you understand why digital encryption has become the standard in modern baby monitors.
Without encryption, the airwaves remain wide open.
