Subject:
|
Re: tracking an IR beacon
|
Newsgroups:
|
lugnet.robotics.handyboard
|
Date:
|
Mon, 8 Dec 1997 09:56:06 GMT
|
Original-From:
|
Peter Harrison <peter.harrison@cannock.ac/spamcake/.uk>
|
Viewed:
|
891 times
|
| |
|
|
The phase difference seen by the sensors would be tiny at any practical
frequency.
Assume that you have the sensors a distance, D, apart and facing
'forward' on the robot. If there is a transmitting source at 90 degrees
to the forward direction, the path difference between the two received
signals is D metres giving a pair of signals with a relative time lag of
D/(3e8) seconds.
Lets make D = 300mm for easy sums and the time difference is now 1
nanosecond. For signals that deviate from 'forwards' by an angle A, the
path difference will be DsinA and significantly smaller than 1
nanosecond most of the time.
In general, for phase diferencing detectors like this to work with the
best sensitivity, the receivers need to be a little less than half a
wavelength apart. For a 40kHz signal you would need about 3.5
kilometers.
Its a good idea but you need to be working at microwave frequencies to
put the things into small units. Radio direction finding at UHF (500 MHz
or so) is quite doable in free space.
Pete Harrison
|
|
Message is in Reply To:
 | | tracking an IR beacon
|
| Hello all - My goal: I'm trying to determine the feasibility of tracking an IR source with my Handy Board. My initial scheme calls for using two IR detectors (the ones with all the internal filters, etc, to provide a clean 5V output upon detection (...) (27 years ago, 6-Dec-97, to lugnet.robotics.handyboard)
|
6 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
