diff --git a/implementation.tex b/implementation.tex
index c903b035ebfd263d6a3aea3ff8d7104860d939b7..5b55e993bce76f6edc4e077bcbaec865b10f4b7e 100644
--- a/implementation.tex
+++ b/implementation.tex
@@ -16,4 +16,23 @@
 
     
     \subsection{Resource and activity planning}
-    \subsection{Time monitoring}
\ No newline at end of file
+    \subsection{Time monitoring}
+
+
+\subsection{IR Sensor development}
+    Two kinds of IR sensors were chosen as a backup, to cover for the sonar should it encounter problems in the mineshaft.
+    As the sonar has a nominal range of $\SI{2}{}$ to $\SI{400}{\centi\meter}$, both of the IR sensors were required to fully cover this range.
+    The short range IR, however, has a minimum range of $\SI{20}{\centi\meter}$.
+    Sensor response within this range coincide with response from targets much further away, leading to unreliable measurment.
+    This was deemed a non-issue, as the minimum distance overlaps with the total copter width.
+    Thus, any measurment values that could be ambiguous can be ignored, as the copter would already have crashed.
+
+    Six clusters of IR sensor pairs (long and short) were to be mounted at $90^{\circ}$ angle relative each other, pointing nominally up, down, forward, backward and to each side.
+    Thus, the double mounted IR clusters could cover the range should the sonar fail.
+
+    As development progressed, issues were found with the IR sensors.
+    Both sensors hade issues with accuracy at range, as well as low update rate, in comparison to the sonars.
+    They were also difficult to implement in software.
+    The decision was thus made that all ADC and IR development were to be put on halt in favour of SPI.
+    Additionally, the focus was to make the short-range IR sensors work first, and have them act mostly as a short-range collision avoidance system.
+    The long-ranged sensors were to be implemented either if the sonar performed poorly or if time could be spared from other parts of the project.