XE1205I074TRLF Просмотр технического описания (PDF) - Semtech Corporation

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XE1205I074TRLF

180 MHz – 1GHz Low-Power, High Link Budget Integrated UHF Transceiver

Semtech Corporation 

XE1205

where OSR(7:0) is the content of the register; TParam_OSR(7:0) as described in section 7.2.8.

For a correct operation of the bit synchronizer, the value of this register must be higher or equal to 15 and

(int(OSR)+1) * Bit_rate should be inferior or equal to 4.87MHz.

5.2.3.3 Pattern recognition block in continuous mode

In receive mode this feature is activated by setting the RXParam_Pattern configuration register bit to high. The

demodulated signal is compared with a pattern stored in the Reg_pattern(31:0) registers. The PATTERN signal (mapped

to output pin IRQ_0) is driven by the output of this comparator and is synchronized by DCLK. It is set to high when a

matching condition is detected, otherwise set to low. PATTERN output is updated at the rising edge of DCLK. The

number of bits used for comparison is defined in the RXParam_Psize(1:0) register and the number of tolerated errors for

the pattern recognition is defined in the RXParam_Ptol(1:0) register. Figure 4, illustrates the pattern matching process.

DATA

(NRZ)

Bit N-x =

Reg_pattern[x]

DCLK

Bit N-1 =

Bit N =

Reg_pattern[1] Reg_pattern[0]

PATTERN

Figure 4: Pattern matching operation.

Note: The pattern recognizer is available only if the bit synchronizer is enabled.

5.2.3.4 RSSI in continuous mode

This function provides a Received Signal Strength Indication based on the signal level at the output of the base-band

filter. To activate this function, the bit RXParam_RSSI must be set to “1”. When activated, the 2-bit status information is

stored in register RXParam_RSSI_OUT(1:0) and may be read through the serial control interface. The meaning of this

status information is given in the table below, where VRFFIL is the differential amplitude of the equivalent input RF signal

when the receiver is operated in mode A. The thresholds VTHRi are at the output of the base-band filter divided by the

gain between the input of the receiver and this output. When operated in mode B, equivalent VTHRi thresholds are

shifted 15dBm higher.

RXPARAM_RSSI_out(1:0) Description

00

VRFFIL ≤ VTHR1

01

VTHR1 < VRFFIL ≤ VTHR2

10

VTHR2 < VRFFIL ≤ VTHR3

11

VTHR3 < VRFFIL

Table 7: RSSI status description

The operating range of the RSSI measurement may be changed by programming the RXParam_RSSI_range bit; in this

way two ranges with three VTHRi values may be selected. An additional way to increase RSSI operating range is to

combine modes A and B thresholds. One could then cover input signals ranging from -110dBm (VTHR1, low range,

mode A) up to -70dBm (VTHR3, high range, mode B)

© Semtech 2008

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