RXC101 Datasheet, PDF (24/33 Pages) RF Monolithics, Inc – Multi-channel High data rate Programmable

Baseband Filter Register [POR=C42Ch]
Bit Bit Bit Bit Bit Bit Bit Bit Bit
Bit Bit Bit Bit
Bit
Bit
Bit
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
1
1
0
0
0
1
0
0 CRLK CRLC 1 FILT 1 DQLVL2 DQLVL1 DQLVL0
The Baseband Filter Register configures:
• Clock Recovery lock control
• Baseband Filter type, Digital or Analog RC
• Data Quality Detect Threshold parameter
Bit [15..8] - Command Code: These bits are the command code that is sent serially to the processor that
identifies the bits to be written to the Baseband Filter Register.
Bit [7] – Automatic Clock Recovery Lock: When set, this bit configures the CR (clock recovery) lock
control to automatic. In this setting the clock recovery will startup in “Fast” mode and automatically switch
to “Slow” mode after locking. See Bit [6] description for details of “Fast” and “Slow” modes.
Bit [6] – Manual Clock Recovery Lock Control: When set, this bit configures the CR lock to “Fast”
mode. “Fast” mode requires a preamble of at least 6 to 8 bits to determine the clock rate, then locks.
When cleared, this bit configures the CR lock to “Slow” mode. “Slow” mode takes a little longer in that it
requires a preamble of at least 12 to 16 bits to determine the clock rate, then locks. Use of the “Slow”
mode requires more accurate bit timing. See Data Rate Setup Register for the relationship of data rate
and CR.
Bit [5] – Not Used. Write a “1”.
Bit [4..3] – Filter Type:
Table 13.
Filter
FILT1
RSSI for OOK 0
Digital
0
Not Used
1
Analog RC
1
FILT0
0
1
0
1
RSSI for OOK: The Analog RSSI Output signal is used to receive the incoming data. The Digital RSSI is
used for data slicing. Set DRSSI parameter in the Receiver Control Register.
Digital Filter: The Digital filter is a digital version of a simple RC lowpass filter followed by a comparator
with hysteresis. The time constant for the Digital filter is automatically calculated internally based on the
bit rate as set in the Data Rate Setup Register.
Analog RC lowpass filter: The baseband signal is fed to pin 7 thru an internal 10K Ohm resistor. The
lowpass cutoff frequency is set by the external capacitor connected from pin 7 to GND. To calculate the
baseband capacitor value for a given data rate, use:
CFILT = 1 / (30,000*Data Rate)
Bit [2..0] – Data Quality Detect Threshold: The threshold parameter should be set less than four (<4) in
order for the Data Quality Detector to report good signal quality in the case that the bit rate is close to the
deviation. As the data rate << deviation, a higher threshold parameter is permitted and may report good
signal quality.
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