EVAL-ADF7021DBZ5 Datasheet, PDF (29/64 Pages) Analog Devices – High Performance Narrow-Band Transceiver IC

Data Sheet
MODULATION AND FILTERING OPTIONS
The various modulation and data filtering options are described
in Table 11.
Table 11. Modulation and Filtering Options
Modulation
Data Filtering
BINARY FSK
2FSK
None
MSK¹
None
OQPSK with half sine
baseband shaping²
None
GFSK
Gaussian
GMSK³
Gaussian
RC2FSK
Raised cosine
Oversampled 2FSK
None
3-LEVEL FSK
3FSK
None
RC3FSK
Raised cosine
4-LEVEL FSK
4FSK
None
RC4FSK
Raised cosine
R2_DB[4:6]
000
000
000
001
001
101
100
010
110
011
111
1 _{MSK is 2FSK modulation with a modulation index = 0.5.}
2 _{Offset quadrature phase shift keying (OQPSK) with half sine baseband}
shaping is spectrally equivalent to MSK.
3 _{GMSK is GFSK with a modulation index = 0.5.}
TRANSMIT LATENCY
Transmit latency is the delay time from the sampling of a
bit/symbol by the TxRxCLK signal to when that bit/symbol
appears at the RF output. The latency without any data filtering
is 1 bit. The addition of data filtering adds a further latency as
outlined in Table 12.
It is important that the ADF7021 be left in transmit mode after
the last data bit is sampled by the data clock to account for this
latency. The ADF7021 should stay in transmit mode for a time
equal to the number of latency bit periods for the applied
modulation scheme. This ensures that all of the data sampled by
the TxRxCLK signal appears at RF.
The figures for latency in Table 12 assume that the positive
TxRxCLK edge is used to sample data (default). If the TxRxCLK
ADF7021
is inverted by setting R2_DB[28:29], an additional 0.5 bit
latency can be added to all values in Table 12.
Table 12. Bit/Symbol Latency in Transmit Mode for Various
Modulation Schemes
Modulation
Latency
2FSK
1 bit
GFSK
4 bits
RC2FSK, Alpha = 0.5
5 bits
RC2FSK, Alpha = 0.7
4 bits
3FSK
1 bit
RC3FSK, Alpha = 0.5
5 bits
RC3FSK, Alpha = 0.7
4 bits
4FSK
1 symbol
RC4FSK, Alpha = 0.5
5 symbols
RC4FSK, Alpha = 0.7
4 symbols
TEST PATTERN GENERATOR
The ADF7021 has a number of built-in test pattern generators
that can be used to facilitate radio link setup or RF measurement.
A full list of the supported patterns is shown in Table 13. The
data rate for these test patterns is the programmed data rate set
in Register 3.
The PN9 sequence is suitable for test modulation when carrying
out adjacent channel power (ACP) or occupied bandwidth
measurements.
Table 13. Transmit Test Pattern Generator Options
Test Pattern
R15_DB[8:10]
Normal
000
Transmit Carrier
001
Transmit + fDEV tone
010
Transmit − fDEV tone
011
Transmit 1010 pattern
100
Transmit PN9 sequence
101
Transmit SWD pattern repeatedly
110
Rev. B | Page 29 of 64