RXC101 Datasheet, PDF (23/33 Pages) RF Monolithics, Inc – Multi-channel High data rate Programmable

Automatic Frequency Adjust Register (continued)
where fres is the tuning resolution for each band as follows:
fres: 315 MHz Band = 2.5kHz
433 MHz Band = 2.5kHz
868 MHz Band = 5kHz
916 MHz Band = 7.5kHz
Bit [3] – Manual Frequency Adjustment Strobe: This bit is the strobe signal that initiates a manual
frequency adjustment sample. When set, a sample of the received signal is compared to the
Receiver LO signal and an offset is calculated. If enabled, this value is written to the Offset
Register (See Bit [1]) and added to the frequency control word of the PLL. This bit MUST be reset
before initiating another sample.
Bit [2] – High Accuracy (Fine) Mode: This bit, when set, switches the frequency adjustment mode to
high accuracy. In this mode the processing time is twice the regular mode, but the uncertainty of
the measurement is significantly reduced.
Bit [1] – Frequency Offset Register Enable: This bit, when set, enables the offset value calculated by
the offset sample to be added to the frequency control word of the PLL that tunes the desired
carrier frequency.
Bit [0] – Offset Frequency Enable: This bit, when set, enables the RXC101 to calculate the offset
frequency by the sample taken from the Automatic Frequency Adjustment circuit.
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