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tdoa distance diff error
Posted: Sat Mar 24, 2018 10:41 am
by justinleeyang
hi,
tdoa anchor mode:
Code: Select all
#define NSLOTS 8
#define TDMA_SLOT_BITS 26 // 26: 2ms timeslot
#define TDMA_NSLOT_BITS 3
about the distance difference between anchors, the right value should be ~0.3m, get many wrong value as follow:
314852.0000
314756.0000
......
358941.0000
then adjust the TDMA_SLOT_BITS to 27, the wrong value reduce, but occurs once Occasionally.
why?
Re: tdoa distance diff error
Posted: Mon Mar 26, 2018 9:56 am
by arnaud
Do you get spikes, intermittent bad values, or is it consistently wrong?
Re: tdoa distance diff error
Posted: Mon Mar 26, 2018 5:29 pm
by Guglie
Very interesting, I'm also trying to get better results from TDOA, what are the TDMA_SLOT_BITS?
Re: tdoa distance diff error
Posted: Tue Mar 27, 2018 2:45 am
by justinleeyang
hi, arnaud:
when TDMA_SLOT_BITS set as 26, consistently wrong;
then set as 27, intermittent bad values.
Re: tdoa distance diff error
Posted: Wed Mar 28, 2018 7:45 am
by arnaud
Hum, this looks like packet collision. Are you using un-modified firmware or have you changed anything. I am thinking about radio settings that could change the packet timing.
Re: tdoa distance diff error
Posted: Wed Apr 04, 2018 12:08 pm
by justinleeyang
yes, I open other tag or anchor, they send ~30 packets per second, so affect my tdoa anchors and tag receive result in distance diff error.
Re: tdoa distance diff error
Posted: Fri Apr 06, 2018 6:08 am
by arnaud
What version of the node firmware are you using (what git commit)?