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Dual Channel Card Audio Levels
Dual Channel Card Audio Levels
Theory of Operation
To adjust the audio levels it is necessary to understand the relationship between the levels
of various types of audio signals used in the system. The voice signals will all pass though
an automatic gain control (AGC). This normalizes the level of speech for a broad range of
input levels. Sine waves such as alert tones that also pass through the AGC are
normalized, but to a different rms level. If the sine wave level is at -6 dB rms then the
speech level will be about -12 dB rms. If the channel being setup uses tone control there
will also be some other transmit tone levels to consider. These are high level guard tone
(HLGT), function tones, and low level guard tone (LLGT). The figure above shows the
relationship between all these signal levels as they leave the dual channel card in a S4000
system. In the example figure it is assumed that the radio input level to cause 67% channel
deviation is -6 dB and that the dual channel card Tx adjustment has been set so the alert
tone level is -6 dB.
The transmit audio level output to the radio is adjustable over a broad range, for
transmitting a sine wave this is from a maximum of +14 dBm and a minimum of silence.
The high level guard tone is 5.5 dB louder than a console generated alert tone. Most voice
peaks are less than 4 to 6 dB above the alert tone peaks. Function tones are 4.5 dB below
the alert tone level. If the alert tone transmit level is set to 67% radio channel deviation the
dashed lines in the example figure will represent the 100% radio deviation level.
Содержание 4000 Series
Страница 1: ...Series 4000 Communication Control System Installation and Configuration 025 9533Y...
Страница 6: ...6 025 9533Y...
Страница 28: ...Introduction 28 025 9533Y...
Страница 88: ...Common Control Equipment Installation 88 025 9533Y Figure 22 Console Duplex Wall Jacks...
Страница 110: ...Common Control Equipment Installation 110 025 9533Y...
Страница 172: ...Console Installation 172 025 9533Y...
Страница 192: ...Audio Level Adjustments 192 025 9533Y...
Страница 230: ...Accessory Installation 230 025 9533Y...
Страница 236: ...Console ANI Programming 236 025 9533Y...
Страница 339: ...339 RSMP Operation Figure 99 Main Screen...
Страница 350: ...Radio System Management Program 350 025 9533Y...
Страница 362: ...Appendix B Troubleshooting 362 025 9533Y...
Страница 417: ...417 Index wiring accessories 164 wall jack 86 wiring diagram for M4219 244 X XMT button labels 332 XP settings 247...
Страница 418: ...Index 418 025 9533Y...