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Issue distinguishing between IR Beacons with IRSeeker V2
http://www.robotc.net/forums/viewtopic.php?f=41&t=12006
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Author:  SergeantFTC [ Wed Aug 19, 2015 7:17 pm ]
Post subject:  Issue distinguishing between IR Beacons with IRSeeker V2

Our goal is to have a robot that can distinguish between a 1200Hz IR beacon and a 600Hz IR beacon. According to HiTechnic's website, this is something that we should be able to do.
Quote:
The IR Beacon transmits either a 600Hz or 1200 Hz signal allowing the IRSeeker sensor to distinguish between two different beacons.


When pointing the IRSeeker at one of the new HiTechnic IR beacons, the IRSeeker sample program from the RobotC Driver suite registers the sensor, regardless of what mode the program has set the sensor to run in, and regardless of whether the IR beacon is set to emit a 600Hz or 1200Hz signal. Since changing the mode of the sensor seems to have little to no effect, it appears that there is an issue with either the sensor itself or its programming. Has anyone else been able to make this work? Is there a bug of some sort in the driver suite, or do we have a faulty sensor?

Author:  mightor [ Thu Aug 20, 2015 12:28 am ]
Post subject:  Re: Issue distinguishing between IR Beacons with IRSeeker V2

Hi there,

I have never tested my sensor with a beacon, as I don't own one. Have you tested the sensor with the standard LEGO software and does it work there?

= Xander

Author:  amare [ Tue Nov 10, 2015 10:51 am ]
Post subject:  Re: Issue distinguishing between IR Beacons with IRSeeker V2

I've used IRSeeker with two beacons for the French Robot Cup.

1/
Do you read AC or DC signal ?

IRSeeker returns values for DC signal and AC signal (600Hz or 1200Hz depending of the configuration of the sensor). The DC signal return values of any IR sources, modulated or not, whatever the modulation.

2/
Do you read the signal strength ? I've already notice that a sensor configured at 600Hz detect a beacon at 1200Hz or umodulated ir sources (sun for exemple !!), but whith a very low signal strength.

My solution to determine if the signal detected is modulated at the right frequency is to compare the DC Signal and AC Signal :
if DC direction = AC Direction and AC signal Strength < 0.8 * DC signal Strength Then the signal detected is not modulated at the right frequency

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