IRForum

Looking at the AnalysIR.ini file, I see the RCA protocol is described as:

[RCA]
Mark=500
Space0=1000
Space1=2000
delta=100
Header=4000
HeaderSpace=4000
Bits=24 #12 actual bit transmiited a second time inverted
Carrier=45000

How was the delta value determined? For example, was it determined empirically? Suppose a user generated an IR code with a mark of 601, did those codes fail all the time?

It is arbitrary based on experience.

Nominally your 601 uSec signal(Mark) would not be recognized. However, if you use the Tolerance slider on the GUI you can vary the tolerance at any time.

The original basis was related to accuracy of IR receivers being +/- 100uSecs (actually up to 200uSecs). Usually the difference is closer to 50 uSecs.

PS: If the Mark is defined as 100uSecs the a delta of 100 uSecs would be too much). SO a good starting point would be 20% of the Mark or space length & no more than 200uSecs