Unheeded Lesson of the Bellah Crosstalk

The loud brieftone that accompanied the Bellah crosstalk provides an opportunity to measure how Channel-I would have reproduced the brieftone that accompanied the Channel-II Decker broadcast.

At about 12:34, Sargent Bellah asked the dispatcher do you want me to still hold this traffic on Stemmons . . .. The loud squeal, which accompanies this message is a brieftone. Feedback from an operating Channel-II receiver within an earshot of Bellah's microphone created the brieftone.

A microphone operating on Channel-I was also within an earshot of an operating Channel-II receiver and broadcasted Bellah's message and the accidental brieftone as crosstalk.

Contrary to the declaration of the Watson Research Center, the frequency response of Channel-I was adequate to respond to the Channel-II brieftone. In fact, spectrographs of Bellah's broadcast and its crosstalk shows the narrower frequency response of Channel-I attenuated the brieftone by less than four decibels.

Similarly a brieftone mars Decker's Channel-II hold everything secure broadcast. In both cases the brieftones are excessively loud signals and only their narrowband characters prevent them from obscuring the broadcasts.

Unlike the Bellah crosstalk where the loudness of the brieftone is comparable with the voice, the alleged Decker crosstalk contains no audible nor measurable brieftone.

The missing brieftone is the first clue that the alleged Decker crosstalk does not match the corresponding portion of the Decker broadcast. Absence of fidelity is the second hint. The badly garbled voice of the alleged Decker crosstalk contrasts sharply with the clarity of the Bellah crosstalk.

Brieftone

When a transmitter operates too close to an active receiver on the same channel the resultant feedback produces a high-pitched oscillation of the entire radio channel. This oscillation is a narrow-band signal and is an excellent marker to measure frequency compression due to a difference between playing and recording speeds of the tapes.

Crosstalk

When a transmitter operates near an active receiver on a different channel the acoustic coupling permits messages from one channel to cross over to the other channel. Of course this crosstalk mechanism does not distinguish voiced messages from other signals. So crosstalk includes heterodynes, brieftones, noise and all other signals.

Frequency Compression

A recording device stores a frequency as a density. For example, suppose the device records a frequency of f cycle per second at a speed of r inch per second. The medium stores f / r cycles per inch. Playing the medium at a speed of p inch per second yields a frequency of f / r cycles per inch multiplied by p inch per second or f p / r cycles per second. In other words the device transforms the frequency of the signal by the ratio of the playing to the recording speeds. They call this ratio a compression.