Doc updates.

protocols/airspy_adsb.md

@@ -18,7 +18,7 @@ level data. Unlike raw format, lines are terminated with `\r\n` (`0x0d 0x0a`).
 * `;` (`0x3b`)
 * 1 byte MLAT precision (see below)
 * `;` (`0x3b`)
-* 2 byte big-endian RSSI
+* 2 byte big-endian [RSSI](https://en.wikipedia.org/wiki/Received_signal_strength_indication)
 * `;\r\n` (`0x3b 0x0d 0x0a`)
   
 

protocols/beast.md

@@ -25,13 +25,13 @@ Escaping makes frame length for a given type variable, up to
 
 ## Frame types
 * `0x31`: Mode-AC frame
-  * 1 byte signal level
+  * 1 byte [RSSI](https://en.wikipedia.org/wiki/Received_signal_strength_indication)
   * 2 byte Mode-AC data
 * `0x32`: Mode-S short frame
-  * 1 byte signal level
+  * 1 byte RSSI
   * 7 byte Mode-S short data
 * `0x33`: Mode-S long frame
-  * 1 byte signal level
+  * 1 byte RSSI
   * 14 byte Mode-S long data
 * `0x34`: Status data
   * *Appears to only be used by Mode-S Beast hardware later versions*
@@ -46,6 +46,12 @@ external time, but receiving software can calculate its offset from other
 receiving stations across multiple packets, and then use the differences between
 station receive timing to calculate signal source position.
 
+FlightAware's dump1090 fork sends 0x000000000000 when it has no MLAT data.
+
+
+## RSSI
+FlightAware's dump1090 fork sends 0xff when it has no RSSI data.
+
 
 ## Examples