RXM-315-LR_1 Datasheet, PDF (3/11 Pages) List of Unclassifed Manufacturers – LR SERIES RECEIVER MODULE DATA

PIN ASSIGNMENTS
1 NC
2 NC
3 NC
4 GND
5 VCC
6 PDN
7 RSSI
8 DATA
ANT 16
GND 15
NC 14
NC 13
NC 12
NC 11
NC 10
NC 9
Figure 7: LR Series Receiver Pinout (Top View)
PIN DESCRIPTIONS
Pin #
1
2
3
4
5
Name
NC
NC
NC
GND
V_CC
Description
No Connection
No Connection
No Connection
Analog Ground
Supply Voltage
Power Down. Pulling this line low will place the receiver
6
PDN
into a low-current state. The module will not be able to
receive a signal in this state.
7
8
9
10
11
12
13
14
15
16
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RSSI
DATA
NC
NC
NC
NC
NC
NC
GND
RF IN
Received Signal Strength Indicator. This line will supply an
analog voltage that is proportional to the strength of the
received signal.
Digital Data Output. This line will output the demodulated
digital data.
No Connection
No Connection
No Connection
No Connection
No Connection
No Connection
Analog Ground
50-ohm RF Input
MODULE DESCRIPTION
The LR receiver is a low-cost, high-performance synthesized AM / OOK receiver,
capable of receiving serial data at up to 10,000bps. Its exceptional sensitivity
results in outstanding range performance. The LR’s compact surface-mount
package is friendly to automated or hand production. LR Series modules are
capable of meeting the regulatory requirements of many domestic and
international applications.
50Ω RF IN
(Antenna)
Band Select
Filter
LNA
10.7MHz
0˚
IF Filter
-
∑
Limiter
+
Data Slicer
Data Out
90˚
RSSI/Analog
PLL
VCO
XTAL
Figure 8: LR Series Receiver Block Diagram
THEORY OF OPERATION
The LR receiver is designed to recover
data sent by an AM or Carrier-Present
Carrier-Absent (CPCA) transmitter, also
referred to as CW or On-Off Keying
Data
(OOK). This type of modulation
represents a logic low ‘0’ by the absence Carrier
of a carrier and a logic high ‘1’ by the
presence of a carrier. This modulation
method affords numerous benefits. The ^{Figure 9: CPCA (AM) Modulation}
two most important are: 1) cost-effectiveness due to design simplicity and 2)
higher allowable output power and thus greater range in countries (such as the
U.S.) that average output power measurements over time. Please refer to Linx
Application Note AN-00130 for a further discussion of modulation techniques.
The LR receiver utilizes an advanced single-conversion superheterodyne
architecture. Transmitted signals enter the module through a 50-ohm RF port
intended for single-ended connection to an external antenna. RF signals
entering the antenna are filtered and then amplified by an NMOS cascode Low
Noise Amplifier (LNA). The filtered, amplified signal is then down-converted to a
10.7MHz Intermediate Frequency (IF) by mixing it with a low-side Local
Oscillator (LO). The LO frequency is generated by a Voltage Controlled
Oscillator (VCO) locked by a Phase-Locked Loop (PLL) frequency synthesizer
that utilizes a precision crystal reference. The mixer stage incorporates a pair of
double-balanced mixers and a unique image rejection circuit. This circuit, along
with the high IF frequency and ceramic IF filters, reduces susceptibility to
interference. The IF frequency is further amplified, filtered, and demodulated to
recover the baseband signal originally transmitted. The baseband signal is
squared by a data slicer and output to the DATA pin. The architecture and quality
of the components utilized in the LR module enable it to outperform many far
more expensive receiver products.
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