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Rev. 0.9
8.1.6.2. AM
Property group 0x2200 configures Channel Filter Bandwidth characteristics for AM.
Two independent Channel Filter Bandwidth engines can be configured using RSSI or SNR and ASSI (independent
±9/10 kHz channel RSSI relative to on-channel RSSI). Channel Filter Bandwidth ranging from minimum to
maximum occurs at the specified widening rate as the metric increases above the minimum threshold and reaches
maximum threshold. Channel Filter Bandwidth ranging from maximum to minimum occurs at the specified
narrowing rate as the metric decreases below the maximum threshold and reaches the minimum threshold. The
resulting Channel Filter Bandwidth is the minimum of the result of the two blend engine calculations.
Property 0x1306 AM_ACF_CONTROL_SOURCE is used to select RSSI or SNR as a metric for the Channel Filter
Bandwidth.
8.1.7. Softmute
Property group 0x0400 configures softmute characteristics for FM and AM.
Property 0x1306 FM_ACF_CONTROL_SOURCE (and AM_ACF_CONTROL_SOURCE) is used to select SNR
(default) or RSSI as a metric for the softmute engine. For FM and AM modes, the property is also used to select
whether an AFC rail condition will engage softmute. The most common cause for an AFC rail condition is tuning to
an idle channel.
Softmute engages as SNR (or RSSI) drops below a trigger threshold and audio level reaches a maximum
attenuation at the end threshold. Softmute releases as SNR (or RSSI) rises above the end threshold and audio
level reaches full level at the trigger threshold. The attack and release rates are configurable along with maximum
attenuation and trigger and end thresholds.
8.1.8. Automatic Volume Control (AVC)
Property group 0x0500 configures automatic volume control (AVC) for AM.
The AVC minimum and maximum gain can be configured. The AVC maintains a constant carrier level.
8.1.9. Mono/stereo Blend
Property group 0x3500 configures the mono/stereo blend characteristics for FM mode.
Six independent blend engines can be configured using RSSI, multipath, and USN as the metric. Blend from
minimum stereo to maximum stereo separation occurs at the specified attack rate as the metric increases above
the minimum threshold and reaches maximum threshold. Blend from maximum stereo to minimum stereo
separation occurs at the specified release rate as the metric decreases below the maximum threshold and reaches
the minimum threshold. The resulting stereo separation is the minimum of the result of the six blend engine
calculations.
8.1.10. HICUT
HICUT applies a lowpass filter to the L+R MPX audio.
8.1.10.1. FM
Property group 0x3600 configures the HICUT characteristics for FM mode.
Six independent blend engines can be configured using RSSI, multipath, and USN as the metric. HICUT from
minimum to maximum occurs at the specified attack rate as the metric increases above the minimum threshold and
reaches maximum threshold. HICUT from maximum to minimum occurs at the specified release rate as the metric
decreases below the maximum threshold and reaches the minimum threshold. The resulting HICUT is the
minimum of the result of the six blend engine calculations.
