xe1202 ETC-unknow, xe1202 Datasheet - Page 8

• Manufacturer Part Number: xe1202
• Description: Low-power, Integrated Uhf Transceiver
• Manufacturer: ETC-unknow

4.1 Detailed description
4.1.1
The outputs of the receiver are the two signals DATAOUT and DCLK. When the bit “RTParam_Bits” is “1” (see the
Configuration register section below), the bit synchronizer is turned on, and the two output signals are respectively
the output NRZ bit stream and the sampling clock. The function of the bit synchronizer is to remove the glitches
from the bit stream DATAOUT and to provide the output clock DCLK. The value of DATAOUT is valid at the rising
edge of DCLK.
For proper behavior of the bit synchronizer, three conditions must be satisfied:
When “RTParam_Bits” is “0”, the bit synchronizer is turned off, and the signal DATAOUT is the output of the
demodulator. In this case DCLK is not used and its value is set to “low”.
The condition on the modulation index for proper behavior of the demodulator is:
where f is the frequency deviation and BR the bit rate.
4.1.2
The receiver can be operated in two different modes that provide the highest sensitivity or the highest linearity. This
is programmable with the register “
4.1.3
When activated, this function provides a Received Signal Strength Indication based on the signal at the output of
the base-band filter. To activate this function, the bit “RTParam_RSSI” (see the Configuration register section
below) must be set “1”. When activated, the status is a 2-bits data stored in register “DataOut_RSSI”, which can be
read through the serial control interface. The meaning of this status information is given in the table below, where
V
thresholds VTHRi are the thresholds at the output of the base-band filter divided by the gain between the input of
the receiver and this output.
Two ranges with three VTHRi are defined and selected with the flag “RTParam_RSSR”.
The time diagram of an RSSI measurement is given in the next figure. When the RSSI function has been activated
the signal strength is periodically measured and the result is stored in the register “DataOut_RSSI” at each rising
edge of the DATAIN. TS_RS is the wake-up time required after the function has been activated to get a valid result.
8
RFFIL
is the differential amplitude of the equivalent input RF signal when the receiver is operated in A-mode. The
-
-
-
-
-
Receiver
High sensitivity vs. high linearity: A-mode, B-mode
RSSI
the received data must start with a preamble of 24 bits for synchronization; this preamble must be a
sequence of “0” and “1” sent alternatively,
after that, the incoming bit stream must have at least one transition from “0” to “1” or from “1” to “0”
every 8 bits,
the accuracy of the bit rate must be better than
39 MHz)
A-mode: the receiver has the highest sensitivity (see RFS parameter)
B-mode: the receiver has the highest linearity (see IIP3 parameter)
2
BR
f
, 2
DataOut_RSSI
RTParam_Rmode
0 0
0 1
1 0
1 1
Table 1 RSSI status description
” (see the Configuration register section below).
VTHR1 < V
VTHR2 < V
5 % (assuming the reference Xtal oscillator is exactly
V
VTHR3 < V
RFFIL
Description
RFFIL
RFFIL
VTHR1
RFFIL
VTHR2
VTHR3
Data Sheet
XE1202
D0211-105