CIRCUIT DESIGN, INC
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CDP-02N UHF Synthesized Radio Data Module Operation Guide
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CDP-TX-02N transmitter module
The CDP-TX-02N (CDP-TX-02AN) is a UHF FM-narrow band transmitter with PLL
synthesizer and micro controller for high frequency stability and channel selectability. Modern
SMT technology enable its small size - much smaller than a match box.
The narrow band FM modulation (direct FSK) allows efficient use of the available RF
spectrum. Different modules can operate in a 25 KHz channel spacing scheme unlike SAW
resonator transmitters which use a very broad band of the frequency spectrum. 32 channels
can be easily selected by use of the chip mounted 4 bits switch and a PCB jumper. Please refer
to the section on channel plan and frequency setting for details.
The CDP-TX-02N (CDP-TX-02AN) can transmit any 5 Volt digital input data in the specified
frequency range. Analog data is digitized by the internal comparator.
In about 80mS (90msec for 458MHz) after the transmitter is connected to a power source,
PLL is locked and data can be transmitted without further control or synchronization
.
The transmission is physically done by a flexible Lambda/4 antenna connected to the module.
The amount of radiated power and the surrounding of the antenna influences directional
behavior. Installation in a bigger metal housing with ground connected to the transmitter
module housing and the transmitter antenna placed in an upright position outside the metal
housing will reduce the antenna impedance and increase the radiated power. For best
performance in a user system general rules of radio frequency technology should be taken into
consideration.
The same considerations should also be applied to the receiver.
CDP-RX-02N receiver module
The CDP-RX-02N (CDP-RX-02AN) is a UHF receiver for FM-narrow band modulated
signals.
The receiver design is based on the double Super-heterodyne principle with PLL synthesize
system and micro controller enabling high signal sensitivity, high selectivity, and high
frequency stability not achieved by simple SAW resonator receivers or other low cost designs.
The channel frequency can be easily selected to match the frequency of the transmitter. The
method of frequency selection is the same as CDP-TX-02N (CDP-TX-02AN).
Extensive filtering by an integrated unique SAW filter element enables operation in hazardous
areas where interference may be expected. Steadily increasing use of the available frequency
spectrum demands the application of narrow band systems for maximum operation reliability
and consideration for other users of the ISM band.
The CDP-RX-02N (CDP-RX-02AN) receiver module is designed to match the CDP-TX-02N
(CDP-TX-02AN) transmitter module, though signals from other FM-narrow band transmitters
can be received as well.
The CDP-RX-02N (CDP-RX-02AN) is designed for mounting on a PCB. A simple wire can
be soldered to the antenna input or the antenna can be printed on the PC board. Better
performance is attained with commercial antennas for the 433MHz (458MHz) ISM band.
The receiver modules have two different outputs and an RSSI field power output which
