AN332
Rev. 0.8
317
To Achieve Similar Performance in SI4704/05/3X-D60 to SI4704/05/3X-C40
The -D60 devices have a more advanced feature set than -C40 devices. This section describes a step-by-step
procedure to achieve similar performance from -D60 devices to that of -C40 devices by modifying or disabling
some of the advanced features.
FM Receiver Mode
There is a debug feature that remains active in Si4704/05/3x-D60 firmware which can create periodic noise in
audio. Silicon Labs recommends you disable this feature by sending the following bytes (shown here in
hexadecimal form):
0x12 0x00 0xFF 0x00 0x00 0x00
In Si4704/05/3x-D60 devices, the FM_BLEND_RSSI_STEREO_THRESHOLD property is no longer at address
0x1105. Use address 0x1800 instead.
In Si4704/05/3x-D60 devices, the FM_BLEND_RSSI_MONO_THRESHOLD property is no longer at address
0x1106. Use address 0x1801 instead.
To disable the SNR-based stereo blend, set both the FM_BLEND_SNR_STEREO_THRESHOLD property
(0x1804) and the FM_BLEND_SNR_MONO_THRESHOLD property (0x1805) to 0.
To disable the multipath-based stereo blend, set both the FM_BLEND_MULTIPATH_STEREO_THRESHOLD
property (0x1808) and the FM_BLEND_MULTIPATH_MONO_THRESHOLD property (0x1809) to 100 (0x64).
AM Receive Mode
Si473x-D60 devices are compatible with Si473x-C40 devices in AMRX mode.
WB Receive Mode
There are no Si473x-D60 devices which support WBRX mode.
To Achieve Similar Performance in SI4704/05/3X-D60 to SI4704/05/3X-B20
The -D60 devices have a more advanced feature set than -B20 devices. This section describes a step-by-step
procedure to achieve similar performance from -D60 devices to that of -B20 devices by modifying or disabling
some of the advanced features.
FM Receiver Mode
There is a debug feature that remains active in Si4704/05/3x-D60 firmware which can create periodic noise in
audio. Silicon Labs recommends you disable this feature by sending the following bytes (shown here in
hexadecimal form):
0x12 0x00 0xFF 0x00 0x00 0x00
In Si4704/05/3X-D60 devices, the FM_BLEND_RSSI_STEREO_THRESHOLD property is no longer at address
0x1105. Use address 0x1800 instead.
In Si4704/05/3X-D60 devices, the FM_BLEND_RSSI_MONO_THRESHOLD property is no longer at address
0x1106. Use address 0x1801 instead.
To disable the SNR-based stereo blend, set both the FM_BLEND_SNR_STEREO_THRESHOLD property
(0x1804) and the FM_BLEND_SNR_MONO_THRESHOLD property (0x1805) to 0.
To disable the multipath-based stereo blend, set both the FM_BLEND_MULTIPATH_STEREO_THRESHOLD
property (0x1808) and the FM_BLEND_MULTIPATH_MONO_THRESHOLD property (0x1809) to 100 (0x64).