Please explain the term "SAW"

Photon

Active Member
In the context of "The wireless door/window sensors are SAW mode 319.5MHZ transmitters," what does "SAW" mean? Surface Acoustic Wave? Standing Acoustic Wave? Is SAW a good thing? Should it impact my sensor selection vs. another sensor that doesn't specify SAW? Inquiring minds want to know.
 
SAW means surface acoustic wave. The main difference in transmitters is between the SAW resonator and the crystal resonator which sets the transmit frequency. SAW resonators tend to jump around the desired frequency more. If it jumps out of the receivers bandpass then the transmission could be missed.

The ELK M1XRF receiver has a narrower bandpass which gives it more sensitivity to weak transmitter signals. In order to guarantee the transmitter's frequency falls within the bandpass frequency of the receiver, ELK recommends using a crystal based transmitter whos transmit frequency will be closer to the center frequency. In the case of the GE transmitters that frequency is 319.5 Mhz.

In monitoring the transmit frequency of some SAW based transmitters with a spectrum analyzer, each time the SAW transmit section powers up, the frequency may shift. I have seen transmissions completely out of the receivers bandpass on some of the 8 transmissions from a transmitter with some of the transmissions in the bandpass.

A SAW transmitter may work OK with the receiver, but ELK does not recommend them.
 
Thank you, Spanky, for replying in terms I can understand.

I'm still waiting for a response to an issue I sent to my lawyer last week. I left a message with my auto's service dept a few days ago. No call back. I've been reading about Elk's outstanding customer support for a couple years, and now I have personally experienced it. I expect to finally have time to install a security system for my new house, and it was easy to decide that Elk is the system for me. A fine response in less than an hour, and I'm not even a customer, yet. Soon, I hope.
 
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