diff --git a/autotune.go b/autotune.go
index f5d25ddc..b18e8a29 100644
--- a/autotune.go
+++ b/autotune.go
@@ -43,11 +43,18 @@ func (tune *autoTune) Sample(bit bool, seq uint32) {
 // Find a period for a given signal
 // returns -1 if not found
 //
-//	  ---              ------
-//	    |              |
-//	    |______________|
-//	        Period
-//	Falling Edge    Rising Edge
+//
+//   Signal Level
+//       |
+// 1.0   |                 _____           _____
+//       |                |     |         |     |
+// 0.5   |      _____     |     |   _____ |     |   _____
+//       |     |     |    |     |  |     ||     |  |     |
+// 0.0 __|_____|     |____|     |__|     ||     |__|     |_____
+//       |
+//       |-----------------------------------------------------> Time
+//            A     B    C     D  E     F     G  H     I
+
 func (tune *autoTune) FindPeriod(bit bool) int {
 	// last pulse and initial index setup
 	lastPulse := tune.pulses[0]
diff --git a/fec.go b/fec.go
index 3437d563..b382d38a 100644
--- a/fec.go
+++ b/fec.go
@@ -20,6 +20,23 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+// THE GENERALIZED REED-SOLOMON FEC SCHEME
+//
+// Encoding:
+// -----------
+// Message:         | M1 | M2 | M3 | M4 |
+// Generate Parity: | P1 | P2 |
+// Encoded Codeword:| M1 | M2 | M3 | M4 | P1 | P2 |
+//
+// Decoding with Erasures:
+// ------------------------
+// Received:        | M1 | ?? | M3 | M4 | P1 | ?? |
+// Erasures:        |    | E1 |    |    |    | E2 |
+// Syndromes:       S1, S2, ...
+// Error Locator:   Λ(x) = ...
+// Correct Erasures:Determine values for E1 (M2) and E2 (P2).
+// Corrected:       | M1 | M2 | M3 | M4 | P1 | P2 |
+
 package kcp
 
 import (