ATA5823 ATMEL Corporation, ATA5823 Datasheet - Page 19

• Manufacturer Part Number: ATA5823
• Description: Uhf Ask/fsk Transceiver Ata5823 Ata5824
• Manufacturer: ATMEL Corporation

7.12
Figure 7-9.
4829D–RKE–06/06
FSK/ASK Transmission
Ref 10 dBm
Samp
Log
10
dB/
VAvg
5 0
W1 S2
S3 FC
Center 433.92 MHz
Res BW 100 kHz
FSK-modulated TX Spectrum (433.92 MHz/20 Kbit/s/ 19.41 kHz/Manchester Code)
Care must be taken regarding the harmonics of the CLK output signal as well as to the harmon-
ics produced by a microprocessor clocked with it, since these harmonics can disturb the
reception of signals. In a single channel system using FREQ = 3803 to 4053 ensures that har-
monics of this signal, do not disturb the receive mode.
Due to the fast modulation capability of the synthesizer and the high resolution, the carrier can
be internally FSK modulated which simplifies the application of the transceiver. The deviation of
the transmitted signal is ±24 digital frequency steps of the synthesizer which is equal to
±18.65 kHz for 315 MHz, ±19.41 kHz for 433.92 MHz and ±19.64 kHz for 868.3 MHz.
Due to closed loop modulation with PLL filtering, the modulated spectrum is very clean, meeting
ETSI and CEPT regulations when using a simple LC filter for the power amplifier harmonics as it
is shown in
FSK transmission and the power amplifier is switched on and off to perform the modulation.
Figure 7-9
pseudo-random data with 20 Kbit/s/±19.41 kHz/Manchester and 5 dBm output power.
Figure
to
Figure 7-11 on page 20
Atten 20 dB
4-1. In ASK mode the frequency is internally connected to the center of the
VBW 100 kHz
show the spectrum of the FSK modulation with
Sweep 7.5 ms (401 pts)
Span 30 MHz
ATA5823/ATA5824
19