ax5051 AXSEM, ax5051 Datasheet - Page 28

• Manufacturer Part Number: ax5051
• Description: Ax5051 Radio
• Manufacturer: AXSEM

28
Circuit Description
5.12. Modulator
Depending on the transmitter settings the modulator generates various inputs for the PA:
h
f
ASK
FSK
MSK
therefore f
demodulated more robustly.
PSK
OQPSK
compatibility to an existing system is required, MSK should be preferred.
All modulation schemes are binary.
5.13. Automatic Frequency Control (AFC)
The
to a carrier signal. For AFC adjustment, the frequency offset can be computed with the
following formula:
FSKMUL is the FSK oversampling factor, it depends on the FSK bit rate and deviation used. To
determine it for a specific case, see the
than FSK, FSKMUL=1.
Version 1.6
deviation
∆
f
AX5051
=
TRKFREQ
Modulation
ASK
FSK / MSK
PSK
= 0.5⋅h⋅BITRATE,
2
deviation
16
has a frequency tracking register
= modulation index. It is the ratio of the deviation compared to the bit-rate;
= amplitude shift keying
= frequency shift keying
= minimum shift keying; MSK is a special case of FSK, where h = 0.5, and
= phase shift keying
= offset quadrature shift keying. The
BITRATE
= 0.25⋅BITRATE; the advantage of MSK over FSK is that it can be
Bit = 0
PA off
∆f=-f
∆Φ=0
AX5051
deviation
0
×
FSKMUL
can demodulate signals with h < 32.
Bit = 1
PA on
∆f=+f
∆Φ=180
deviation
.
0
AX5051
TRKFREQ
Main Lobe Bandwidth
BW=BITRATE
BW=(1+h) ⋅BITRATE
BW=BITRATE
Programming Manual. For modulations other
AX5051
to synchronize the receiver frequency
supports OQPSK. However, unless
Max. Bitrate
600kBit/s
200kBit/s
600kBit/s
Datasheet AX5051