Fix ADR half cycle ambiguity doc (hardware/interfaces)
Bug: 190846015
Test: n/a
Change-Id: I6339018bc5b3764d51db61458d208ca7e99b4d81
diff --git a/current.txt b/current.txt
index 3102972..387f9ec 100644
--- a/current.txt
+++ b/current.txt
@@ -770,7 +770,7 @@
e042522daa4b5f7fd4a0a19bcdadb93c79a1b04c09ef2c9813a3a8941032f3f5 android.hardware.contexthub@1.0::IContexthub
c2f64133b83ede65c9939ef97ab5bd867b73faf3dba0e7e69f77c3c43d9e487e android.hardware.contexthub@1.0::IContexthubCallback
bda492ec4021d13869de72bd6f8c15c5837b78d6136b8d538efec5320573a5ec android.hardware.gnss@1.0::IGnssMeasurementCallback
-6a271e493907e8ba20912e42771bd0d99ae45431a851d5675ef9496d02510a34 android.hardware.gnss@1.1::IGnssMeasurementCallback
+7ae2025662e30e690a3ffa1c65cc972c6297a68638174055c33cbf3d2e4bbddc android.hardware.gnss@1.1::IGnssMeasurementCallback
11e9e1a1fd0c9b3d9648750d4b10dc2a839d3a6688904c3fc49500a4e7ca75b0 android.hardware.gnss@2.1::IGnssMeasurementCallback
2c331a9605f3a08d9c1e0a36169ca57758bc43c11a78ef3f3730509885e52c15 android.hardware.graphics.composer@2.4::IComposerClient
3da3ce039247872d95c6bd48621dbfdfa1c2d2a91a90f257862f87ee2bc46300 android.hardware.health@2.1::types
diff --git a/gnss/1.1/IGnssMeasurementCallback.hal b/gnss/1.1/IGnssMeasurementCallback.hal
index 36841ee..f94c67a 100644
--- a/gnss/1.1/IGnssMeasurementCallback.hal
+++ b/gnss/1.1/IGnssMeasurementCallback.hal
@@ -24,13 +24,38 @@
* Flags indicating the Accumulated Delta Range's states.
*
* See the table below for a detailed interpretation of each state. This is
- * a continuation of the table from 1.1/IGnssMeasurementCallback.hal.
+ * a continuation of the table from 1.0/IGnssMeasurementCallback.hal.
*
* +---------------------+-------------------+-----------------------------+
* | ADR_STATE | Time of relevance | Interpretation |
* +---------------------+-------------------+-----------------------------+
* | HALF_CYCLE_RESOLVED | ADR(t) | Half cycle ambiguity is |
* | | | resolved at time t. |
+ * | | | |
+ * | | | For signals that have |
+ * | | | databits, the carrier phase |
+ * | | | tracking loops typically |
+ * | | | use a costas loop |
+ * | | | discriminator. This type of |
+ * | | | tracking loop introduces a |
+ * | | | half-cycle ambiguity that |
+ * | | | is resolved by searching |
+ * | | | through the received data |
+ * | | | for known patterns of |
+ * | | | databits (e.g. GPS uses the |
+ * | | | TLM word) which then |
+ * | | | determines the polarity of |
+ * | | | the incoming data and |
+ * | | | resolves the half-cycle |
+ * | | | ambiguity. |
+ * | | | |
+ * | | | Before the half-cycle |
+ * | | | ambiguity has been resolved |
+ * | | | it is possible that the |
+ * | | | ADR_STATE_VALID flag is |
+ * | | | set, but the ADR_STATE_ |
+ * | | | HALF_CYCLE_RESOLVED flag is |
+ * | | | not set. |
* +---------------------+-------------------+-----------------------------+
*/
enum GnssAccumulatedDeltaRangeState
diff --git a/gnss/aidl/android/hardware/gnss/GnssMeasurement.aidl b/gnss/aidl/android/hardware/gnss/GnssMeasurement.aidl
index 58f29c5..efecddd 100644
--- a/gnss/aidl/android/hardware/gnss/GnssMeasurement.aidl
+++ b/gnss/aidl/android/hardware/gnss/GnssMeasurement.aidl
@@ -438,6 +438,31 @@
* +---------------------+-------------------+-----------------------------+
* | HALF_CYCLE_RESOLVED | ADR(t) | Half cycle ambiguity is |
* | | | resolved at time t. |
+ * | | | |
+ * | | | For signals that have |
+ * | | | databits, the carrier phase |
+ * | | | tracking loops typically |
+ * | | | use a costas loop |
+ * | | | discriminator. This type of |
+ * | | | tracking loop introduces a |
+ * | | | half-cycle ambiguity that |
+ * | | | is resolved by searching |
+ * | | | through the received data |
+ * | | | for known patterns of |
+ * | | | databits (e.g. GPS uses the |
+ * | | | TLM word) which then |
+ * | | | determines the polarity of |
+ * | | | the incoming data and |
+ * | | | resolves the half-cycle |
+ * | | | ambiguity. |
+ * | | | |
+ * | | | Before the half-cycle |
+ * | | | ambiguity has been resolved |
+ * | | | it is possible that the |
+ * | | | ADR_STATE_VALID flag is |
+ * | | | set, but the ADR_STATE_ |
+ * | | | HALF_CYCLE_RESOLVED flag is |
+ * | | | not set. |
* +---------------------+-------------------+-----------------------------+
*/
const int ADR_STATE_UNKNOWN = 0;