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--- doc:lps:tdoa3:protocol [2018-05-02 13:45]
kristoffer
+++ doc:lps:tdoa3:protocol [2019-09-05 14:45]
kimberly
@@ Line 1: / Line 1: @@
-====== TDoA Anchor protocol V3 (experimental) ======
-<WRAP center round tip 80%>
+<WRAP center round important 60%>
-**NOTE**
+This page is deprecated and is moved to the main Bitcraze website. Please go to:
-This is work in progress. The specifications on this page may change at any time without backwards compatibility.
+ [[
+https://www.bitcraze.io/docs/lps-node-firmware/master/tdoa3_protocol/
+]]
 </WRAP>
-This page describes the [[doc:lps:tdoa3|TDoA]] anchor protocol V3.
+====== TDoA Anchor protocol V3 ======
-===== System architecture =====
+===== Design goals =====
-The protocol is designed to be used with a large number of anchors covering a big area. Each anchor has a limited reach and covers only a small area, but by adding more anchors the system will be able to cover an (virtually) unlimited area. At any point in the covered area, 5-10 anchors should be within range of a Tag.
+The protocol is designed to be used with a large number of anchors covering a big area. Each anchor has a limited reach and covers only a small area, but by adding more anchors the system can cover an (virtually) unlimited area. At any point in the covered area, 5-10 anchors should be within range of a Tag.
 Each anchor knows its own position in a global coordinate system and broadcasts this information in time stamped packets that are used by one or more Tags to estimate their position.
@@ Line 20: / Line 21: @@
 ===== Packet scheduling =====
-Packets are transmitted at random times and collisions are handled by the system.
+Packets are transmitted at random times and collisions are handled by the receiving party.
 ===== Packet format =====
-There is only one packet format.
+<ditaa>
+                    +--------+--------------------+----------+
+Packet    :         | Header | Remote anchor data | LPP data |
+                    +--------+--------------------+----------+
-<code c>
+bytes
-typedef struct {
+                     <------------------------------------------->
-    uint8_t id;            // The id of the remote anchor
+bits   8 bits     32 bits       8 bits
-    uint8_t seq;           // Sequence number of latest packet received from the remote anchor
+                     <------> <------> <-----------> <----------->
-    uint16_t distance;     // Time of flight between the current anchor and the remote anchor in radio timer ticks
+                    +--------+--------+-------------+-------------+
-    uint32_t rxTimeStamp;  // Receive time stamp of latest packet from the remote anchor
+Header    :         |  type  |  seq   | txTimeStamp | remoteCount |
-} __attribute__((packed)) remoteAnchorData_t;
+                    +--------+--------+-------------+-------------+
-typedef struct {
-  uint8_t type;            // 0x30
+or 8 bytes
-  uint8_t seq;             // The sequence number of this packet
+                     <---------------------------------------------------------->
-  uint32_t txTimeStamp;    // Transmission time of this packet
+bits      1 bit      7 bits     32 bits     0 or 16 bits
+                     <------> <-----------> <------> <-----------> <------------>
+                    +--------+-------------+--------+-------------+--------------+
+Remote anchor data: |   id   | hasDistance |  seq   | rxTimeStamp |   distance   |
+                    +--------+-------------+--------+-------------+--------------+
+</ditaa>
-  uint8_t remoteCount;     // The number of slots in the following section that are populated with data
+  * **Header**
-  remoteAnchorData_t remoteData[LOCODECK_NR_OF_TDOA3_ANCHORS];
+    * **type:** 0x30
-} __attribute__((packed)) rangePacket3_t;
+    * **seq:** the sequence number of this packet 0 - 127
-</code>
+    * **txTimeStamp:** transmission time of this packet
+    * **remoteCount:** the number of slots in the Remote Anchor Data section that are populated with data, max 8
+  * **Remote anchor data**
+    * **id:** the id of the remote anchor
+    * **hasDistance:** 1 = distance data is included in the remote anchor data, total length is 8 bytes, otherwise it is 6 bytes.
+    * **seq:** sequence number of latest packet received from the remote anchor 0 - 127
+    * **rxTimeStamp:** receive time stamp of latest packet from the remote anchor
+    * **distance:** time of flight between the current anchor and the remote anchor in radio timer ticks
+  * **LPP data:** See [[doc:lps:lpp#lpp_short_packets|LPP short packet description]]
 ===== Tag implementation =====
-A TDoA tag is simply an UWB sniffer. A sniffer can use the data in the packets together with the packet receive timestamps to calculate its position.
+A TDoA tag is simply an UWB sniffer. A sniffer can use the data in the packets together with the timestamps when packets are received to calculate its position.
+===== Calculating TDoA =====
+[[doc:lps:tdoa:principles|Please see TDoA positioning principles]]

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