SX1230, Revision 2 May 2009

©2008 Semtech Corp.

SX1230

www.semtech.com

Page 40

Integrated Transmitter IC

ADVANCED COMMUNICATIONS & SENSING

DATASHEET

9.4. SX1230 Baseband Filtering

The following figure illustrates the effect of applying the baseband gaussian filtering to the modulating bitstream of the

868 MHz,

unfiltered bit stream to 330 kHz with a filtering coefficient (BT) of 1. By increasing the filtering strength further to BT=0.3,

the channel bandwidth for operation in the 868 MHz ISM band is reduced to below 200 kHz.

Figure 31. The Influence of Gaussian Filtering on the Modulation Bandwidth (Wideband)

9.5. Adjacent Channel Power

Modulation spectrum of the SX1230 measured in 100 Hz bandwidth is shown in the following three figures together with

the integrated adjacent channel power for the modulation settings shown in the figure caption. Please note that all

measurements were performed at 868 MHz, with an output power of 13 dBm. Please also note that the clock output was

disabled.

-70

-60

-50

-40

-30

-20

-10

0

10

-500

-400

-300

-200

-100

0

100

200

300

400

500

Offset from Centre Frequency (kHz)

No Filtering

'BT = 1

'BT = 0.3

ETSI Limit