Internal limited gaussian distribution function should not clip edge values

[w7sst]

Description

The internal gaussian distribution function, RndGaussLim(AMean, ALim), currently uses a clipping algorithm to eliminate values above and below the specified limit argument. This creates an unwanted spike on the edges of the probability distribution curve. The improved algorithm is to eliminate these over-the-limit values by dropping them.

This function is used in the implementation of the following behaviors:

• delay time for a calling station to wait before sending next transmission.
• when creating a station, its Pitch is computed using Gaussian Limit function.
  • For Single Calls, Pitch is in range [-50, 50] (e.g. RndGaussLim(0, 50))
  • For other modes, Pitch is set to a value in the range [-300, 300] (e.g. RndGaussLim(0, 300)
• when creating Qrm stations, their Pitch is set to a value in the range [-300, 300] (e.g. RndGaussLim(0, 300))

Steps To Reproduce

This problem was found by code inspection and cannot be readily reproduced with the application.

Expected behavior

Values outside of the limited gaussian distribution should be eliminated, not clipped.

Actual Behavior

The current behavior is clipping these values. This may cause a higher percentage appearance of these edge values.

Version information

• Morse Runner version: found in 1.84, but has probably been in the code for a long time, perhaps since 1.68.

Additional context

This article has an example showing the effects of clipping a limited gaussian distribution.

BTW, I discovered this problem while looking at a reported possible audio clipping problem. The user was using a bluetooth headset during copy. Initially my thought was centered around clipping of the audio signal. This was not the case. However, I stumbled across the implementation of RndGaussLim(AMean, ALimit) and discovered it was using a clipping algorithm (min/max) which clips the value at the two end values. This technique results in a non-gaussian distribution.

Tasks

• Coding
• Code review and integration
• Validation