What types of surveillance devices for children exist?
The most advanced models are the baby monitors with camera, which, in addition to allowing you to listen and/or talk to your baby, also offer the possibility of watching him on a small mobile screen. In this way you will have total control over your baby and you can stay anywhere in the house. Depending on the model chosen, it is possible to have different features: night vision, automated video camera for baby control, zoom, etc.
The other type are the devices which transmit and receive only audio. They can be unidirectional, that is, they only allow you to listen to the baby; or two-way, to be able to talk to him and calm him down. They are a good option if you want simple equipment used to punctually check on the child as you spend most of your time with him.