A desired characteristic associated with a signal generated by a programmable transmitter is determined. The signal may be combined with other signals to form a combined signal, and sub-optical monitoring may be performed on the combined signal to determine an optical characteristic associated with the signal. The optical characteristic may be evaluated to determine if the programmable transmitter is operating improperly. For example, if the optical characteristic does not conform to a desired range of values, it is determined whether the optical characteristic is intentionally set outside of the desired range. A tuning instruction to reconfigure the programmable transmitter may be generated if the programmable transmitter is operating improperly.