Introduction
8
Digital Audio
The digital processing of voice audio is a major innovation in the performance of tone
remote controllers. It not only provides clean and sharp audio at the speaker, but it also
makes the remote easier to use.
An operator can begin speaking immediately upon pressing the transmit button. With
other tone remotes, it is necessary to wait first for the function tones to be sent to the base
station; otherwise, the initial syllables of the operator's words are clipped off because the
station was not keyed yet. The Models 280 and 284 include an innovative, momentary
digital delay that buffers the voice audio while the remote is sending the function tones.
This supports critical communications by always allowing the dispatchers to speak
instantly, instead of having to force themselves to remember to wait a second to let the
remote catch up.
The capability to speak immediately makes the Models 280 and 284 ideal for upgrading
dispatch centers where the operators are accustomed to using DC remotes. They can
transition to the new tone remote equipment without having to develop a new set of habits
when they go to transmit.
The Model 280 and 284 have the capability to mute all incoming guard and function tones
from parallel remotes. A tone detector combined with a momentary audio delay allows for
complete tone muting.
Automatic Audio Leveling
Most remote-controlled radio systems require control from multiple points. The various
audio levels are thus often quite different, depending upon their point of origin and the
path taken back to the base station. Mobile radios, parallel remotes, and distant remotes
may all sound different to the operator. The Zetron Digital Tone Remotes address these
issues through the use of high-quality, digital audio processing similar to that used in CD
players. Even if a given audio level fluctuates on a daily basis, these remotes detect the
change and compensate for it.
Reliable Audio Quality
Other tone remotes use analog filters and tone generators that require precise adjustment
and ongoing maintenance. If these designs are not serviced regularly, they will degrade
with time and temperature, and eventually become unreliable and offer poor quality audio.
The circuits in the Digital Tone Remotes, on the other hand, are crystal-controlled for
stable operation over the specified temperature range. The audio quality does not drift and
suffer with age. The remote even performs a self-test every time it is powered up to verify
proper operation.
