3.2 Additional Tests
3.2.1 FSK Modulation
Direct digital FSK modulation is supported in LMX2571. FSK PIN mode supports discrete 2-, 4-, or 8-level FSK
modulation while other FSK modes support arbitrary level FSK modulation.
example.
Table 3-2. FSK PIN Mode Example
PARAMETER
EXAMPLE VALUE
Phase detector frequency
80 MHz
CHDIV1
Divided by 4
CHDIV2
Divided by 1
PLL_DEN
2
24
Prescalar
2
Frequency deviation
±600 Hz; ±1800 Hz
Continue to toggle the FSK_D[1:0] and FSK_DV pins, the output is a discrete 4-level FSK modulated signal.
Figure 3-3. FSK PIN Mode Setting
Figure 3-4. FSK PIN Mode
3.2.2 Register Readback
To read back the written register values, use the following steps:
1. From the TICS Pro, set SDO_LD_SEL to
Lock detect output
.
Typical Measurement
SNAU182 – MARCH 2021
LMX2571EPEVM Evaluation Instructions
7
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