ADF7021 datasheet(29/64 Pages) AD

29 / 64 page

Data Sheet

ADF7021

Rev. B | Page 29 of 64

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

R2_DB[4:6]

BINARY FSK

2FSK

None

000

MSK1

None

000

OQPSK with half sine

baseband shaping2

None

000

GFSK

Gaussian

001

GMSK3

Gaussian

001

RC2FSK

Raised cosine

101

Oversampled 2FSK

None

100

3-LEVEL FSK

3FSK

None

010

RC3FSK

Raised cosine

110

4-LEVEL FSK

4FSK

None

011

RC4FSK

Raised cosine

111

MSK is 2FSK modulation with a modulation index = 0.5.

Offset quadrature phase shift keying (OQPSK) with half sine baseband

shaping is spectrally equivalent to MSK.

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

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

ADF7021 bảng dữ liệu(PDF) 29 Page - Analog Devices

ADF7021 bảng dữ liệu(HTML) 29 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

bảng dữ liệu tải về

Link URL