Buzz
A baby monitor works as a radio transmitter on a set frequency that emits a clear FM signal when powered on. Most baby monitors transmit at fixed frequencies like 49.300, 49.830, 49.845, 49.860, 49.875, or 49.890 MHz (some models have an A/B switch to select between two of these). If the monitor is placed in an upstairs room and the house lacks aluminum siding, even a basic radio scanner can easily pick up all sounds from that room. A radio scanner typically has a more sensitive receiver than your baby monitor, allowing it to detect the signal from up to half a mile away.
Radio scanners are fairly easy to find at consumer electronics stores, with many current models covering the 49-50 MHz range. These frequencies are just above those used by older analog cordless telephones from the '80s and '90s, and just below the frequencies used by VHF TV channel 2.
To prevent eavesdropping, simply turn off the monitor when it isn't actively monitoring your baby.
Since a baby monitor is essentially a small radio station, there are several creative uses once your baby gets older. For instance, you could place it near a TV speaker when you want to listen to a show but need to be in another room or outside. Alternatively, you could use the monitor to hear a distant doorbell or beeper.
Explore these resources to deepen your understanding:
- How Radio Functions
- Understanding the Radio Spectrum
- How Radio Scanners Operate
- How Cordless Phones Work
- Understanding Wiretapping
- Scanning Resources & Information
- Strong Signals - an extensive site for scanner enthusiasts
- Introduction to Scanning
- Monitoring Times - a magazine for scanner aficionados
