Central apnea is very rare in adults but quite common in babies especially those who were born prematurely. Unlike obstructive apnea, this can happen at any time of the day. The third type of apnea is called mixed apnea. This condition is the combination of obstructive apnea and central apnea. This is particularly very common in infants. More often than not, these portable monitors send out signals between the range of 49,830 MHz and 49,890 MHz. Why do you need to buy one? Mobile baby monitors make it possible for parents to keep tabs on their infants without the necessity of staying awake or standing outside the nursery door all night. The other kind of baby monitor takes away this disadvantage of distance. Wireless technology is already being used in baby monitors. You can move freely around the house and complete your chores while still being able to monitor your baby. Wireless Baby Monitors can be used to either audio or video baby monitors. This is a very good system when it comes to baby monitors the only setback is that, the length of wires makes mobility quite impossible. The receiver would more or less just stay in one place. Wireless baby monitors however are more flexible than wired ones. Since it is wireless, the limitation that the length of wires provide does not apply to it making it more possible to move around the house while still being able to monitor your baby. In case interference is a big issue for you, you can always look for something that utilizes the so-called no-interference technology or has additional security features. Video Monitoring Options A basic baby monitor allows you to hear whatever's happening in the baby's bedroom. Then again, technological innovations have made it possible to combine sound and visual monitoring. Another advantage is that the digital models do not have as much static and they give a clearer sound quality so you can hear your baby better. Video monitorsallow you to see and hear your child by combining sound and video just like miniature TV sets. They use a small camera either mounted on the wall, table or crib to transmit the images into the LCD display.