RFM65W Datasheet, PDF (17/71 Pages) List of Unclassifed Manufacturers – ISM RECEIVER MODULE

ADVANCED COMMUNICATIONS & SENSING
RFM65W
DATASHEET
3.3.4. Lock Time
PLL lock time TS_FS is a function of a number of technical factors, such as synthesized frequency, frequency step, etc.
When using the built-in sequencer, the RFM65W optimizes the startup time and automatically starts the receiver when
the PLL has locked. To manually control the startup time, the user should either wait for TS_FS max given in the
specification, or monitor the signal PLL lock detect indicator, which is set when the PLL has is within its locking range.
When performing an AFC, which usually corrects very small frequency errors, the PLL response time is approximately:
In a frequency hopping scheme, the timings TS_HOP given in the table of specifications give an order of magnitude for the
expected lock times.
3.3.5. Lock Detect Indicator
A lock indication signal can be made available on some of the DIO pins, and is toggled high when the PLL reaches its
locking range. Please refer to Table 17 and Table 18 to map this interrupt to the desired pins.
3.4. Receiver Description
The RFM65W features a digital receiver with the analog to digital conversion process being performed directly following
the LNA-Mixers block. The zero-IF receiver is able to handle (G)FSK and (G)MSK modulation. ASK and OOK modulation
is, however, demodulated by a low-IF architecture. All the filtering, demodulation, gain control, synchronization and
packet handling is performed digitally, which allows a very wide range of bit rates and frequency deviations to be selected.
The receiver is also capable of automatic gain calibration in order to improve precision on RSSI measurements.
3.4.1. Block Diagram
Rx Calibration
Reference
LNA
Single to
Differential
Σ/Δ
Mixers Modulators
Channel
Filter
DC
Cancellation
Complex
Filter
CORDIC
Phase
Output
FSK
Demodulator
RFIN
Local
Oscillator
AFC
Bypassed
in FSK
Module
Output
RSSI
OOK
Demodulator
AGC
Figure 5. Receiver Block Diagram
The following sections give a brief description of each of the receiver blocks.
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