CC2400-RTR1 datasheet(38/84 Pages) TI

38 / 84 page

CC2400

SWRS042A

Page 38 of 83

27 FSK Modulation Formats

The data modulator can modulate 2FSK,

which is two level FSK, and GFSK, which

is a Gaussian filtered FSK with BT=0.5 at

1 Mbps (for lower data rates BT will be

higher).

The purpose of the GFSK is to make a

more bandwidth efficient system. The

modulation and the Gaussian filtering is

performed

internally.

The

GRMDM.TX_GAUSSIAN_FILTER

bit

enables the GFSK.

However, if GFSK modulation is used

together with a data rate of 1 Mbps, it is

recommended to use a preamble length of

32 bytes as otherwise packet error

performance can be affected.

Figure 18 shows a plot of the spectrum for

FSK and GFSK modulation. Input data

was a PN9 sequence. The plot was

captured using a spectrum analyzer set to

5 MHz span and 300 kHz RBW.

-70

-60

-50

-40

-30

-20

-10

2,438

2,439

2,440

2,441

2,442

2,443

Frequency [GHz]

FSK

GFSK

Figure 18. Modulated spectrum

28 Built-in Test Pattern Generator

The

CC2400 has a built-in test pattern

generator that can generate a PN9

pseudo

random

sequence.

The

MDMTST0.TX_PRNG bit enables the PN9

generator.

The PN9 pseudo random sequence is

defined by the polynomial x

9 + x5 + 1.

The PN9 generator can be used for

transmission of ‘real-life’ data when

measuring

modulation

bandwidth

occupied bandwidth.

CC2400-RTR1 数据表(PDF) 38 Page - Texas Instruments

CC2400-RTR1 数据表(HTML) 38 Page - Texas Instruments

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