• State Verified Answer
  • Locked Locked
  • Replies 6 replies
  • Subscribers 62 subscribers
  • Views 5228 views
  • Users 0 members are here
Attachments (0)
Nordic Case Info
  • Case ID: 103568
Options
This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Direction finding with RSSI

iforce2d

I want to make a robot that can track the direction of the transmitter that is controlling it, for example to aim a camera at the transmitter. The robot vehicle will be controlled by a 2.4ghz NRF24L01+ link from within about 40 meters away.

I have seen some fairly simple methods to do similar kinds of tracking by comparing the RSSI from two directional antennas, for example here: www.rcgroups.com/.../showthread.php

It seems that I might be able to do this with a pair of nRF51822 modules, because they have RSSI available. If so, is it possible for the nRF51822's to just listen for the RSSI of the NRF24L01+, without interfering with the controller link in any way? I know the NRF24L01+ can transmit to multiple receivers, but could the nRF51822 make use of the same signal?

  • 0

    The example of the antenna tracker you link to is different from your case for two reasons:

    • Their goal is to aim an antenna in such a way as to optimise the RSSI, not physically pointing at the receiver
    • The receiver is high in the air and as such is in near free space

    In your case this is unlikely to work as RSSI is not strictly directional in the general case (affected by multi path, antenna pattern, etc etc).

    Other than that, yes you could have the nrf51822 modules listen to the signal from the NRF24l01+, the modules won't interfere with the link much though the antennas could if placed in close proximity.

  • 0 in reply to Janek Mann

    He can manage to determine the direction of transmitter with a mechanically rotatable directional antenna.

  • 0 in reply to Janek Mann

    Yes, I'm just trying to manage her/his expectations; in a real, non-freespace environment, the direction found will not point the camera directly at the transmitter.

  • 0 in reply to Janek Mann

    Thanks for the replies. Yes you have a good point, the FPV pilots are not interested in aiming the antenna at the plane itself. Eventually I'm hoping that my 'vehicle' will be a quadcopter, so multipath issues should not be a major concern. I think I will give this a try anyway, since it's fairly cheap and easy, and see how it goes :)

  • 0 in reply to Janek Mann

    I was talking about having on pilot side (on the ground) omnidirectional antenna and on plane side is directional antenna that can mechanically rotate. Plane antenna direction can be automatically adjust to the maximum RSSI position. So first plane can scan all 360°and determine the maximum RSSI direction and after this keep traking this direction deviations. And it can periodically rescan all 360° to determine if it's still the maximum RSSI direction. But better way is to have continiously rotating antenna and scan all the 360° all the time.

Related