SI477X-EVB Datasheet, PDF (19/62 Pages) Silicon Laboratories – Complete antenna-to-audio evaluation system

Si477x-EVB
5.7. FM Receive Mode
Initialize the receiver as described in Section “4.2. Initialization”, selecting FM mode. The Tuner panel will appear
as shown in Figure 23. “FM Tuner Window”.
Figure 23. FM Tuner Window
1/2.Frequency Numerical Window/Slider: Use to set the receiver frequency. This also acts as an indicator
for receive frequencies selected by seek or preset features. Note that frequency resolution is set by the
Band and Spacing properties of the tuner via the Properties window.
3.Tuning Increment/Decrement: Adjusts receiver frequency in increments set by the Spacing property.
4. Seek: Executes tuner Seek command as configured by the applicable Seek/Tune properties.
5. Auto Scan: Executes sequential tuner Seek commands to cover the entire band. Valid stations are
denoted beneath the tuner by red tick marks. Clicking the To Presets button automatically populates the
presets with the strongest twelve stations found.
6. Presets: Each Preset button stores frequencies for convenient recall. Frequencies may be either
automatically programmed using the Auto Scan as described above or may be manually set by selecting a
frequency and holding the desired button until the frequency is memorized.
7. Volume/Mute: Sets the audio L/R output volume. The Mute button engages the AUDIO_MUTE property
for both channels.
Note: Volume must be set to maximum (63) for all performance tests.
8. Status Indicators: These indicators show the various metrics reported back to the user via either the
FM_RSQ_STATUS, FM_AGC_STATUS or FM_ACF_STATUS API commands. Commonly used metrics
include:
RSSI: The Received Signal Strength Indicator at the IC input. Note that this will vary from the actual antenna
RSSI due to front end gains or losses.
SNR: The Signal to Noise Ratio at the demodulator input. Note that this is not the SNR of the Audio output.
LASSI: Low Side Adjacent (100 kHz) Channel Strength Indicator reports the (Signal + Noise) power relative to
the carrier.
HASSI: High Side Adjacent (100 kHz) Channel Strength Indicator reports the (Signal + Noise) power relative to
the carrier.
ASSI200: The 200 kHz offset alternate signal strength indicator. Indicates (signal + noise) at the 200 kHz
offset alternate channel in dB relative to the wanted carrier. Returns the maximum of high and low side
alternate channels.
Rev. 0.4
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