Out of range detection
Out of range detection
(OP)
I need to develop an out of range detection device. When the reciver/transmitter moves out of range from a "base station" it would trigger an event. The range would need to be variable from 3 ft to 15 ft (+/- 20%) and any "line of sight" option will not work. I researched RFID however since this system needs to be portable, and battery operated, the power requirements were to great and the range was limited. Any other ideas?





RE: Out of range detection
The speed of light (RF) is a bit fast for 3 feet. How about ultrasonic sonar pings as the basic ranging technology ?
RE: Out of range detection
The GPS data could be transmitted by the mobile unit to the base station, which could then compute the difference, and decide if the mobile unit was out of range.
RE: Out of range detection
RE: Out of range detection
RE: Out of range detection
Very low frequencies are more stable and the components are cheaper and easier to put together. If you could separate the two units by 3 feet, then hit a calibrate button and measure the changes in power. Outdoors it may work well, indoors and around complicated outdoor structures may be iffy. You'll need frequencies in the 1-20 Mhz range probably, essentially RFID.
Try it with an AM radio and an RF generator first.
kch
RE: Out of range detection
RE: Out of range detection
Maybe just an audio tone generator and detector could be used, like the old tuning fork tv channel changers. Use different signal levels for each distance
kch
RE: Out of range detection
All your ideas are interesting. Higgler you're right in the application, it's not a measuring device but one that will just let me know when something has left a predetermined area. I'm an electrical engineer by occupation so my knowledge in RF is limited but I'm willing to do some research if I knew better which direction to look into. Higgler, I liked your idea of measuring the power received could this easily (and cheaply) be done in a portable devise? Anyone know of any "single chip" solutions out there that can do this.
RE: Out of range detection
time. There are chips to do this since every single cell phone requires this feature to function in a cell.
Here's a simple explaination:
http://
Here's a chip:
h