Analog Devices ADRV9005 Reference Manual page 224

Reference Manual ADRV9001
POWER SAVING AND MONITOR MODE
A "DETECTED" state is asserted once the input signal level is beyond the threshold in the "DETECTING" state, and then the following "Wake
Up" procedure is started. For example, if the threshold is set to −50 dBFS, when a signal strength higher than this threshold is detected then it
is moved to the "DETECTED" state.
Note: this mode is currently only available in DMR profile.
SYNC Mode
The "SYNC" detection monitor mode is intended only for the DMR standard. Configure the receiver datapath in the "frequency deviation" mode
to enable the related functions of the Receiver Demodulator. In the NB FSK block, there is a correlator that can compare received code to some
expected vectors. The correlator detects the SYNC code from the incoming data stream and up to 14 different SYNC code detection can be
supported simultaneously. Similarly, once a SYNC code is detected, the ADRV9001 starts the wake-up procedure.
In this mode, it is required that the Rx interface gain is set to 0 dB as the interface gain is applied prior to the 'NB FSK' block which expects 0dB
of interface gain.
A path delay calibration is required to run in this mode. This calibration measures the delay between the buffer and the SYNC detection block.
This path delay is needed to synchronize the buffer read function. The calibration result can also be saved and stored and uploaded later to
avoid needing to run the calibration on each boot.
FFT Mode
The "FFT" detection mode is only available for the standards that use the FM/FSK modulation scheme. Configure the receiver datapath in the
"frequency deviation" mode to enable the related functions of the Receiver Demodulator. This mode uses the frequency discriminator hardware
block (described in the Frequency Deviation Output Mode section) to demodulate FM/FSK signals. The data is passed to the ARM MCU which
performs a real-time 64 bin FFT of the signal and subsequently uses an FM/FSK detection algorithm to check for a valid FM/FSK signal. Once a
valid FM/FSK signal is detected, the ADRV9001 starts the wake-up procedure.
Note: this mode is currently not available. The maximum channel bandwidth of this mode is limited by the frequency discriminator which is
currently 25 kHz.
RSSI SYNC Mode
RSSI SYNC mode combines the functionality of RSSI and SYNC modes to achieve a more specific method of detection using a dual detection
process. Simultaneously, the signal RSSI is compared to a configurable threshold level similar to the RSSI detection mode and analyzed
for inclusions of DMR Sync codes similar to Sync Detection Mode. If the RSSI detection and SYNC detection both detect a valid signal the
ADRV9001 starts the wake-up procedure.
The settings for RSSI SYNC mode are similar to RSSI Mode and SYNC Mode respectively and the same limitations apply. Use this mode to
avoid false positive detection of SYNC codes by checking that the signal level is valid also.
Note: this mode is currently not available.
RSSI FFT Mode
RSSI FFT mode combines the functionality of RSSI and FFT modes to achieve a more specific method of detection using a dual detection
process. Simultaneously, the signal RSSI is compared to a configurable threshold level and analyzed for a valid FM/FSK signal. If the RSSI
detection and FFT detection both detect a valid signal the ADRV9001 starts the wake-up procedure.
The settings for RSSI FFT mode are similar to RSSI Mode and FFT Mode respectively and the same limitations apply. Use this mode to avoid
false positive detection of FM/FSK signal by checking that the signal level is valid also.
Note: this mode is currently not available.
Monitor Mode Advanced Features
Fast Buffer Read
A fast read of the buffer can be enabled when valid data has been detected. The incoming Rx data is continuously buffered and when the
monitor mode enters the 'detected' state, the buffered data can be read out at 2, 4, or 8x the sample rate until the buffer is cleared. This mode
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