A baby monitor technology includes a simplex (unidirectional) radio transmitter and receiver system equipped with a microphone and a receiver equipped with a speaker. The microphone is placed near to the child and the receiver is carried by, or near to, the person caring for infant.

The frequency used by the devices usually lies in the range of 49'50 megahertz, though some models can go as high as 900 MHz. As with all wireless transmission systems there is the possibility that a receiver used by a third party could pick up the transmissions. To aid this many models allow a choice of bands. A wireless baby monitor doesn't have any wire or cord attached to it.

There have in the past been baby monitors that used a length of cable (around 100m) instead of radio or, for more details visit to www.babies-tips.com alternatively, using mains wiring.

The batteries are the major source of power for the baby monitors. The transmitter stays with the infant crib and is usually plugged into a socket.

Types of baby monitors:

A baby monitor equipped with a digital camera to show video footage on the receiver is called baby video monitor or digital baby monitor. The digital camera in the baby camera monitor works similar method to web cams, and some others allow the receiver to be plugged into a television.

Some baby monitors are duplex (bi-directional), using transceivers that allow the caregiver to communicate back to the baby, for more details visit to www.create-super-baby.com and some have a feature allowing music to be played on the transmitter (and thus played to the child). Such devices sometimes are equipped with video facility also and they are known as baby video and 2 way sound monitor.

There are some devices equipped with movement sensors on the transmitter allowing it to warn caregivers of possible sudden infant death syndrome. The device monitoring heartbeat is known as baby heart monitor or baby heartbeat monitor and the device-monitoring baby breathing is known as baby breathing monitor.

Some monitors have a vibrating alert on the receiver making it particularly useful for people with hearing difficulties. Some baby monitor packages include two receivers.