Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: how does it work
Document: Its not going to work perfectly out of the box.
This product did not work as described. I have already reviewed this product and would not recommend its purchase.Complete dud. Did not work as advertised
The dog barking is so fake...no dog barks like that.After many positioning trys,could not get the item to work properly...even thru glass.
Sometimes the only way to shut the dog up is to turn it off or unplug it. Does not work rightall the time. I bought the Rex Barking Dog sometime ago and I love him, he sounds so real. WishI had gotten another Rex instead.
The "Electronic Barking dog alarm"  does not work properly....It would not bark a sufficient loud bark on cue and would not bark so it could be heard outside the door. It was not effective so as to discourage an intruder. It is very unsatisfactory. I am returning the "Electronic Barking Dog Alarm"
Too respective (after 90 seconds)  for humans to believe its really a dog. Does not work through stucco walls or steel doors. I bought it to keep a bear out of our mountain cabin, and it works 100% in that regard. Buy a &#34;Fake TV&#34;  to go with this to double the affect.
but can't get anything to work. It also gets 'stuck' and continues to bark after you've left the room and there's no motion. I was very excited about the product when I saw it but will be returning it. I also purchased the Rex version (which is identical, only more money)...same problems. Get a real dog if you can.
The unit says there will be different sensitivity in different weather, perhaps rain, etc. I think I have experienced that quirk also. If you want it to work right under different conditions, then the battle for adjusting sensitivity begins anew. Sorry about that.The unit does not see through walls either.
I highly recommend buying at least two remote sensors. This only sounds off if you are in the same room with it. It does not work even through a window. However, the remote sensors make this awesome. I do not recommend this unit by itself. It must have the remote sensor to work properly. Once you have the sensors it is the best little protector there is.
It does work, however if you are trying to use it to protect against intruders to your home it will not pick up anyone on the outside of your house if you have aluminum siding. I set mine on a large window ledge behind drapes and it does very well that way. It also seems more sensitive when approached from the rear so I have the back facing out to the deck.
Answer: The Home Safe EWD-1 contains an infrared sensor that detects temperature changes in the surrounding area.  As such, it does not actually respond to motion, but rather changes in heat.