It uses 2.4GHz FHSS technology that offers a private connection between the monitor in your baby's room and the dedicated viewer in your hand. The FHSS connection should minimize interference, and most reviewers say the audio is clear. In BabyGearLab's testing, the reviewer found that the Phillips AVENT had the best audio signal of any of the monitors it tested.
To save on battery life, some audio/video models only turn on when the baby makes an unusual motion or sound. Some models come with a motion-detector pad that fits under the crib sheet. This type of motion sensor is intended to prevent SIDS. Sensitive enough to detect changes in breathing, an alarm sounds if there is no movement after 20 minutes. However, if the baby simply rolls off the pad, the alarm may sound.
Wireless encryption: This ensures that no one else can tap into your monitor’s “feed” and see what’s going on in your house. WiFi-enabled monitors are great for portability and range, but may be more susceptible to hacking. If you go this route, be sure to secure your home wireless network and keep the monitor’s firmware updated. Otherwise look for digital monitors with a 2.4 GHz FHSS wireless transmission.