Since the signal is affected by distance, reflections, obstacles, etc., it can change quite a bit when moving the sender or receiver around.
We can used this to have a bit of fun. My example setup is the same as described in the previous mail: two Bens, called "ben" and "jlime", both running atrf-proxy and attached to a PC. First, run atrf-path in GUI mode and move one of the Bens (or both) around until the waveform looks interesting: atrf-path -g -T -0.5 -p 0 net:ben net:jlime 10 Then hit "Q" to quit. Next, while keeping the Bens in the same position, do a measurement without the GUI and dump the result to a file: atrf-path -T -0.5 -p 0 net:ben net:jlime 10 >out Check the result with the "plot" script: ./plot out Use the genpathprof script to generate a profile. E.g., leave a clearance of 5 dB above and below the reference spectrum: ./genpathprof +5 +5 out >tunnel Last but not least, run atrf-path with the profile we just generated: atrf-path -g -T -0.5 -p 0 -P tunnel net:ben net:jlime 10 The challenge is now to position the Bens again such that the spectrum ends up in the boundaries. Here's what this can look like: http://downloads.qi-hardware.com/people/werner/wpan/tmp/atrf-path-snake.png The yellow triangle indicates that the spectrum exceeds the maximum at least at one point. A downward red triangle would be shown whenn the minimum is crossed. Finally, a green disc would mean that the spectrum is within the boundaries. When the green disc appears, hit "P" for "Pass". atrf-path will then exit, printing "#PASS". The pass/fail logic works as follows: - if the measurements are all within the limits (green disc) and "P" is pressed, atrf-path prints "#PASS" and exits. "P" is ignored in any other situation. - if at least one measurement is above the maximum, this means that the result is "too good to be true" and something is wrong with the test setup. Maybe someone is walking past the table, a device is not in the right position, there is some interference, etc. atrf-path shows the yellow upward triangle and ignores all keys but "Q" until the disturbance has been resolved. - "Q" always quits, but prints neither "#PASS" nor "#FAIL". - finally, if at least one measurement is below the minimum and no measurement is above the maximum, the red downward triangle appears and "F" can be used to indicate failure. The assumption here is that the test is made in an imperfect environment and the operator has to decide when the measurement is stable and free from external effects. In a more controlled environment, the non-interactive mode of atrf-path can be used. There, all results must agree with the profile for the test to pass. The test fails if all sweeps have at least one value below the minimum and no value is ever above the maximum. All other cases indicate some inconsistency and atrf-path makes no pass/fail decision. The purpose of this test is to detect manufacturing problems, affecting the RF side, e.g., components that are missing, not soldered, shorted, etc. Devices with such problems would show clearly reduced performance. - Werner _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
