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doc:lps:twr-tdma [2017-07-18 15:41]
arnaud [System performance]
doc:lps:twr-tdma [2018-10-19 07:24] (current)
arnaud
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 ====== TWR-TDMA ====== ====== TWR-TDMA ======
 +
 +<WRAP center round important>​
 +**Note**: TWR-TDMA is now considered obsolete and replaced by the TDoA modes. TDoA will generally have better performance than TWR-TDMA, TWR might still be useful to you though but if you are setting up a single room system TDoA is most likely the way to go.
 +</​WRAP>​
 +
  
 ===== Abstract ===== ===== Abstract =====
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 In order to activate TWR-TDMA, you need to recompile the Crazyflie firmware. Add the following to '​tools/​make/​config.mk':​ In order to activate TWR-TDMA, you need to recompile the Crazyflie firmware. Add the following to '​tools/​make/​config.mk':​
-<​code>​+<​code ​make>
 LPS_TDMA_ENABLE=1 LPS_TDMA_ENABLE=1
 CFLAGS += -DTDMA_NSLOTS_BITS=1 CFLAGS += -DTDMA_NSLOTS_BITS=1
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   * **LPS_TDMA_ENABLE=1** Enable the TDMA mode for TWR   * **LPS_TDMA_ENABLE=1** Enable the TDMA mode for TWR
-  * **TDMA_NSLOTS_BITS=1** Configures 2 time slot (good for 2 tags). The number of time slot is 2^TDMA_NSLOTS_BITS +  * **TDMA_NSLOTS_BITS=1** Configures 2 time slot (good for 2 tags) per frame. The number of time slot per frame is 2^TDMA_NSLOTS_BITS 
-  * **TDMA_SLOT** Optionally hardcode the time slot. See bellow for time slot auto-configuration.+  * **TDMA_SLOT** Optionally hardcode the time slot. See bellow for time slot auto-configuration
  
 ===== Configuring time slots ===== ===== Configuring time slots =====
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 TWR-TDMA is currently implemented with time slots of 4ms. Each time slot is used by one tag to range with one anchor. This means that the ranging rate is of //1/(0.004 * 2^TDMA_NSLOTS_BITS)//​ and the rate of update of the full system is //1/(0.004 * 2^TDMA_NSLOTS_BITS * nAnchors)// where nAnchors is the number of anchors in the system. TWR-TDMA is currently implemented with time slots of 4ms. Each time slot is used by one tag to range with one anchor. This means that the ranging rate is of //1/(0.004 * 2^TDMA_NSLOTS_BITS)//​ and the rate of update of the full system is //1/(0.004 * 2^TDMA_NSLOTS_BITS * nAnchors)// where nAnchors is the number of anchors in the system.
  
-The more timeslots, the less often measurements can be used to estimate the tag position and so the performance of the position estimate will deteriorate. For a great number of tag the [[doc:​lps:​tdoa|TDoA]] mode is better suited.+The more timeslots ​per frame, the less often measurements can be used to estimate the tag position and so the performance of the position estimate will deteriorate. For a great number of tag the [[doc:​lps:​tdoa|TDoA]] mode is better suited.
doc/lps/twr-tdma.1500385283.txt.gz · Last modified: 2017-07-18 15:41 by arnaud