5
West Mountain Radio
Operating Manual
Noise Reduction Performance
The noise reduction is dynamic and adaptive. It senses the random
character of the voice or CW and permits it to pass through. The
repetitive nature of the noise is sensed and reduced according to the
patented algorithms. Take notice of the DSP battling the difference
between the voice and the noise when both are at equal level and
the noise is constantly varying.
When the signal is CW, its intermittent character is sensed and the
CW is passed through. The noise is attenuated. When the noise
is steady, such as a heterodyne from a 40 meter broadcast station
(carrier whistle), it is attenuated greatly to over 50 dB or about 0.003
times the original value. If the noise is a varying siren, it is greatly
reduced as well, but not as much as a heterodyne.
Transient sounds are greatly reduced, especially if they are repetitious.
The net effect of the Digital Signal Processor is to reduce atmospheric
noise, static, hiss, ignition noise, power line noise, carriers, hum, and
heterodynes, while passing voice and CW signals.
The adaptive nature of the noise reduction is apparent by observing
its convergent time. A single audible tone will vanish in about 1
second. White noise diminishes in 1 to 2 seconds. Typical car noise
and emergency alarms take about 2 seconds to reduce.
Power Amplifier
CLRspkr contains a power amplifier integrated circuit. It produces
7.5 watts RMS maximum into 8 ohms, when connected to a 13.8
volt DC source. The voltage gain is 46 dB typically. The amplifier
has protection from a shorted speaker.
