RXM-900-HP-II Linx Technologies Inc, RXM-900-HP-II Datasheet - Page 7

• Manufacturer Part Number: RXM-900-HP-II
• Description: RECEIVER RF 900MHZ 8-CH PACK
• Manufacturer: Linx Technologies Inc

Specifications of RXM-900-HP-II

• Frequency: 902MHz ~ 928MHz
• Sensitivity: -95dBm
• Data Rate - Maximum: 50 kbps
• Modulation Or Protocol: FM, FSK
• Applications: Home / Industrial Automation, Remote Access, Security Alarms
• Current - Receiving: 18mA
• Data Interface: PCB, Through Hole
• Antenna Connector: Through Hole
• Voltage - Supply: 2.7 V ~ 16 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 18-SIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Memory Size: -
• Other names: RXM-900-HP2; RXM-900-HP2

BOARD LAYOUT CONSIDERATIONS
Figure 11: Suggested PCB Footprint
The first IF frequency is 34.7 MHz. This frequency is achieved by setting the
synthesizer frequency to a value that is lower than the incoming RF energy from
the antenna.
A high-performance IF receiver strip is used to perform the second conversion
and the FM demodulation. The IF strip takes the 34.7 MHz frequency from the
first conversion, mixes it with a high-precision 24.0 MHz crystal oscillator-
generated frequency to produce the second IF of 10.7 MHz, and amplifies it in
preparation for FM demodulation.
FM demodulation is achieved with an on-board gilbert multiplier. The output of
the IF strip is a demodulated waveform that, after filtering, very closely resembles
the original waveform used to modulate the transmitter.
A high-performance, active low-pass filter cleans up the audio signal, removing
all of the unwanted noise from the FM demodulation process. The output of this
filter is provided to the audio output pin and to the BitPERFECT bit slicer, which
uses proprietary methods to support a wide dynamic range of modulation rates
(300 bps to 50Kbps) with no prerequisites for waveform duty cycle.
An on-board micro-controller is used to manage receiver functions and to provide
a simple interface to external circuitry. The micro-controller performs the following
functions:
- FREQUENCY SYNTHESIZER PROGRAMMING: The micro-controller reads
the three-channel select input lines and programs the frequency synthesizer
registers to the proper values for a given channel. This frees the user from
complex programming requirements and allows for manual channel selection via
switches in product designs where a microprocessor is not used.
- BASEBAND DATA QUALIFICATION: The micro-controller monitors the signal
quality and squelches the data output when the signal is not strong enough for
accurate data detection. This prevents noise on the data output pin during
low-signal or no-signal conditions.
If you are at all familiar with RF devices you may be concerned about
specialized layout requirements. Fortunately, because of the care taken by
Linx in the layout of the module’s PCB, integrating an HP Series-II receiver
into your design is very straightforward. By adhering carefully to a few basic
design and layout rules, you can enjoy a trouble-free path to RF success.
.060"
.030" Dia. Finished
.060"
.10"
Figure
suggested PCB footprint for
the HP Series-II receiver.
A ground-plane (as large as
possible) should be placed
directly under the HP-II
receiver. This ground-plane
can also be critical to the
performance
antenna.
11
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