Increase precision

Decawave Developers Forum Main Forum
#1

Hi
I got 2 questions regarding precision which I have not seen answered anywhere:

  • Would it be possible to increase precision for TDoA systems if one would introduce several receivers (eg 3) per anchor location and average the results.
    Has anyone tried this out and is this feasable or just a useless effort?

  • how reproducible are the results for one specific location? Meaning, if tag returns to the exact same location what precision can I expect?

Thanks in advance for your inputs.
Best regards
Thomas

#2

  1. It would help if done correctly. But putting 3 antennas next to each other will cause them have an impact on each other which could change the results. Sharing 1 antenna between 3 units would result in a signal level drop which would cancel out some of the benefit.
    Putting 3 times the number of anchors in different locations would probably be better.

  2. Repeatability is generally fairly good.
    There are two types of error, measurement noise that causes the position to bounce around and system errors. Measurement noise is always going to be there but averaging can reduce the impact. System errors will give you an error in the average location. This will be due to setup errors, antenna effects and other characteristics of the system setup.
    Since system errors are constant for a given setup and tag location and will be repeatable. So if you average a tag location, move it and then move it back you should get the same average location.

#3

Hi Andy
thanks for the quick reply.
One additional question:
You write: “It would help if done correctly. But putting 3 antennas next to each other will cause them have an impact on each other which could change the results.”
Is this also there case in a TDoA situation where just the tag is sending a point and anchor antennas just need to receive this ping?
Thank you and best regards
Thomas

#4

I don’t pretend to be an RF engineer but from my understanding yes. If nothing else they are metallic elements close to the antenna, that can change the gain pattern of the antenna.
How much impact this would have I have no idea.

#5

Thank you Andy. Your info cover me a idea.
Best regards
Thomas