Adds LSL doc page

neon/data-collection/lab-streaming-layer/index.md

@@ -1,2 +1,50 @@
 # Lab Streaming Layer
-This page is still a work in progress. To use LSL with Neon you need to use our [LSL Relay](https://github.com/pupil-labs/lsl-relay). More documentation is coming soon!
+
+[Lab Streaming Layer](https://labstreaminglayer.org/) (LSL) is an open-source framework that connects, manages, and synchronizes data streams from multiple sources, such as EEG, GSK, and motion capture systems. Check out the [LSL documentation](https://labstreaminglayer.readthedocs.io/info/intro.html) for a full overview of supported devices.
+
+The Neon Companion App has built-in support for LSL, streaming Neon’s real-time generated data over the LSL network. This allows you to easily synchronize Neon with other LSL-supported devices.
+
+## **Usage**
+
+LSL streaming can be initiated in the Companion App by enabling the "Stream over LSL" setting.
+
+When enabled, data will be streamed over the LSL network, and subsequently, to any connected LSL inlet (such as the LSL LabRecorder App, or another third-party system with inlet functionality) which is listening. Like the [Real-Time API](https://docs.pupil-labs.com/neon/real-time-api/tutorials/), it is not necessary for the Companion App to be actively recording, but simultaneously streaming LSL data while making a recording is supported.
+
+Note that you'll need to ensure the Neon Companion App is connected to the same network as the other devices streaming via LSL.
+
+## **LSL Outlets**
+
+When LSL streaming is enabled, two [outlets](https://labstreaminglayer.readthedocs.io/info/intro.html#term-stream-outlet) will be created. One streams [gaze data](https://docs.pupil-labs.com/neon/data-collection/data-streams/#gaze) and [eye-state data](https://docs.pupil-labs.com/neon/data-collection/data-streams/#_3d-eye-states) (if enabled), while the other streams [event data](https://docs.pupil-labs.com/neon/data-collection/events/#events). The streams will be named as:
+
+- `[Device Name]_Neon Gaze`
+- `[Device Name]_Neon Events`
+
+Where `[Device Name]` is the name of the device as configured in the Companion App settings. When synchronizing data from two or more Neon devices using LSL, a unique device name can be assigned to each Companion App so that their streams can be distinguished.
+
+### **Gaze Data Outlet**
+
+The gaze and eye-state stream follows the recommendations of the [xdf Gaze Meta Data format](https://github.com/sccn/xdf/wiki/Gaze-Meta-Data). Two channels labeled `x` and `y` carry the gaze coordinate in scene-camera space. With eye-state estimation enabled, additional channels for each eye will be available with the following labels:
+
+- `PupilDiameter`: the diameter of the pupil in mm
+- `EyeballCenterX`: the x-position of the center of the eyeball from the scene camera
+- `EyeballCenterY`: the y-position of the center of the eyeball from the scene camera
+- `EyeballCenterZ`: the z-position of the center of the eyeball from the scene camera
+
+### **Event Data Outlet**
+
+The event stream contains the name of each generated event as a string.
+
+## Connection problems?
+
+If your devices are on the same network but you have trouble connecting, it is likely due to a firewall or other network configuration issue. LSL requires the following network connections:
+
+- UDP broadcasts to port `16571` and/or
+- UDP multicast to port `16571` at
+    - `FF02:113D:6FDD:2C17:A643:FFE2:1BD1:3CD2`
+    - `FF05:113D:6FDD:2C17:A643:FFE2:1BD1:3CD2`
+    - `FF08113D:6FDD:2C17:A643:FFE2:1BD1:3CD2`
+    - `FF0E:113D:6FDD:2C17:A643:FFE2:1BD1:3CD2`
+    - `224.0.0.1`, `224.0.0.183`, `239.255.172.215`
+- TCP and UDP connections to the ports `16572`-`16604`
+
+More troubleshooting tips can be found in the [Network Troubleshooting](https://labstreaminglayer.readthedocs.io/info/network-connectivity.html) page in LSL’s documentation.