RTX-24EM
User guide
The technical characteristics can change without notice. AUR°EL S.p.A doesn’t assume the responsibility to the damages caused by an improper use of the device.
AUR°EL S.p.A.
Via Foro dei Tigli, 4 - 47015 Modigliana (FC) – ITALY 12/11/2019 - Rev. B
Tel.: +390546941124 – Fax: +390546941660 Page 6
http://www.aurel.it
5.1
RF transceiver
The highly integrated multi-channel RF transceiver is ideal for wireless applications in the world-wide,
license-free, ISM frequency band at 2.4000GHz to 2.4835GHz. Its robust low-IF architecture and direct FSK
modulation scheme are designed for proprietary communication protocols. The EM9209 supports data
transmission rates of 1.5kbps to 72kbps for up to 20 channels.
The RF transceiver can be programmed to one of two primary modes:
Transmit mode: the entire transmit-chain is active and the digital baseband data can be up-converted to a
2.4GHz FSK modulated signal.
Receive mode: the frequency synthesizer and the entire receive-chain are active and ready to receive a
packet.
The RF transceiver consists of three major subsystems:
•
the frequency synthesizer/phase-locked loop (PLL)
•
the receiver
•
the transmitter.
Each of these is described below.
5.1.1 Frequency synthesizer / Phase-Locked Loop (PLL)
The frequency synthesizer provides an accurate, low jitter (-100 dBc @ 1MHz offset) 2.4GHz RF signal used
for both up conversion (in Transmit mode) and down-conversion (in Receive mode). Up to 20 different RF
channel frequencies can be synthesized in high sensitivity mode. Additionally, the PLL supports direct FSK
modulation for use in the Transmit mode.
An auto-calibration mechanism is included in the PLL to center the VCO control voltage.
5.1.2 Receiver
The receiver achieves high sensitivity (-115dBm at 1.5kbps in high sensitivity (HS) mode) and supports a
wide input signal range (up to +10dBm at 2.4GHz). It is comprised of a low noise amplifier (LNA), followed
by a down-conversion mixer and an IF-filter. The output of the IF-filter is fed to a limiting-amplifier which
feeds the digital FSK demodulators (normal and high sensitivity).
The receiver includes a Received Signal Strength Indicator (RSSI), which can measure the down-converted
RF power after the IF filter. The average power on the channel or burst power of a packet can be read via
the SPI after the single-shot RSSI measurement has been completed (see Section 9.11).
5.1.3 Transmitter
The transmitter consists of an FSK modulator with a programmable bit-rate (1.5kbps to 72kbps) which is
included in the frequency synthesizer and a programmable Power Amplifier (PA) output stage.
