Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

BAND WIDTH AND READABILITY 61Listening TestsWith the signal-to-noise ratio characteristics as described above,it can be seen that the answer to the question regarding the relativereadability obtainable with systems using different maximum frequencydeviations depends upon the magnitude of signal-to-noise ratio requiredfor a given readability. For instance, taking the curves of Figure 1,Fig. 3—Oscillograms of internal receiver noise appearing at the frequencymodulation receiver output. A is with carrier-to-noise ratio at the thresholdor "sputter point". B is with carrier-to-noise ratio above the threshold.if readability is obtainable on the narrower system for the signalstrengths which are below the threshold of the wider system, thenarrower system will have a range of superiority in readability ofweaker signals. As will be seen from the following curves, practicallyfull readability is obtained right down to the improvement thresholdof the narrower system. With the wider system, full readability is