XE1202 データシートの表示（PDF） - Unspecified

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XE1202

433MHz / 868MHz / 915MHz Low-power, integrated UHF transceiver

Unspecified 

Data Sheet

XE1202

RTParam_RSSI

en

rssi_out

XX

VAL1

VAL2

VAL3

VAL4

XX

datain

DataOut_RSSI

XX

VAL2

VAL4

TS_RS

Figure 1 RSSI measurement timing diagram

For applications where the time needed to get the first right result from the RSSI has to be as low as possible, this

time can be minimized by waking up the RSSI during mode 010 instead of 100 which is the condition for the

definition of TS_RS in page 6 (for definition of modes, see pages 19 and 20).

4.1.4 Frequency Error Indicator - FEI

When activated, this function provides information about the frequency error of the local oscillator compared with

the input carrier frequency. The condition on the modulation index for proper behavior of the FEI function is:

β

=

2⋅∆f

BR

≥ 2,

where ∆f is the frequency deviation and BR is the bit rate.

There are 2 modes of operation for this function selected by the bit “RTParam_Fsel” (see the Configuration register

section below).

IMPORTANT NOTE

To guarantee proper behavior of the FEI, the sum of frequency offset and the signal bandwidth (ssb) should be

lower than the baseband filter bandwidth (single sided). That is

foffset + SignalBW < Baseband_filterBW

where foffset is the difference between the carrier frequency and the LO frequency, SignalBW is the signal bandwidth

(single sided) equal to the sum of the bitrate divided by 2 and the frequency deviation (Bitrate/2 + Frequency

Deviation), and Baseband_filterBW is the channel filter bandwidth defined by the RTParam_BW parameter (see the

Configuration Registers section below).

4.1.4.1 “RTParam_Fsel” = 1

To activate the FEI function, the bit “RTParam_FEI” must be set to “1”. When activated, the function provides a 2-

bits status stored in register “DataOut_FEI”. The meaning of this output is given in the following table, where fLO is

the internal local oscillator frequency, and fRF is the carrier frequency of the received signal.

DataOut_FEI

Meaning

00

fLO-fRF ≤ fERR

01

-

10

(fLO-fRF) > fERR

11

(fLO-fRF) < -fERR

Table 2 FEI status description

9

D0211-105

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