4421-DKDB1 Silicon Laboratories Inc, 4421-DKDB1 Datasheet - Page 33

• Manufacturer Part Number: 4421-DKDB1
• Description: KIT DEV TEST EZRADIO SI4421 TRX
• Manufacturer: Silicon Laboratories Inc

Specifications of 4421-DKDB1

• Accessory Type: Test Card, Transceiver, 915MHz
• Wireless Frequency: 915 MHz
• Interface Type: SPI
• Modulation: FSK
• For Use With/related Products: EZRadio®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

Si4421
RX-TX ALIGNMENT PROCEDURES
RX-TX frequency offset can be caused only by the differences in the actual reference frequency. To minimize these errors it is
suggested to use the same crystal type and the same PCB layout for the crystal placement on the RX and TX PCBs.
To verify the possible RX-TX offset it is suggested to measure the CLK output of both chips with a high level of accuracy. Do not
measure the output at the XTL pin since the measurement process itself will change the reference frequency. Since the carrier
frequencies are derived from the reference frequency, having identical reference frequencies and nominal frequency settings at the
TX and RX side there should be no offset if the CLK signals have identical frequencies.
It is possible to monitor the actual RX-TX offset using the AFC status report included in the status byte of the receiver. By reading out
the status byte from the receiver, the actual measured offset frequency will be reported. In order to get accurate values the AFC has
to be disabled during the read by clearing the en bit in the AFC Control Command (page 21).
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