[email protected] said: > I guess i don't understand. If you start a counter with the start pulse from > the local chrono, and send back a stop pulse from the start pulse of the > distant chron over the zigbee link using an interrupt on the distant > controller, the response time can be subtracted. Simple calibration of the > electronics delay should be measureable?
I was assuming a dumb/simple RF link, either on-off keying or FSK, with low power and low baud rate and that 800 m would be pushing the operating range. I was assuming that the filters would take longer to respond at (very) low power levels so you couldn't calibrate the delay when the transmitter was next to the receiver and expect to get the same answer when they were 800 meters apart. This may not be significant. Ballpark worst case delay would be the baud rate, 1 ms at 1200 and 100 microsec at 9600. Maybe more for the initial carrier turn-on until the AGC settles in. Has anybody measured the delay through the Xbee units? They are totally different type of operation with lots of opportunity for delays due to retransmission and such (I think). [I guess I'll add that to my list.] The Xbee Pro units claim to have a range of a mile. Has anybody tried them? I just took at look at round trip times using WiFi. Lots of hits around 3 ms with obvious noise up to 5 ms, then a band at 10 ms and another fuzzy band at 20 ms. That's from a PC over Ethernet to an AP, then WiFi to a laptop. I assume some of the noise is ARP and such. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
