ASCELL3911 データシートの表示（PDF） - austriamicrosystems AG

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ASCELL3911

ISM 868 MHz, 433 MHz and 315 MHz FSK Transmitter

austriamicrosystems AG 

ISM 868 MHz, 433 MHz and 315 MHz FSK Transmitter – Preliminary Data Sheet

ASCell3911

Note: CRYSTAL and RANGE are bits of the control information.

Austria Mikro Systeme International AG

1.2 Microprocessor Clock

The microprocessor clock frequency FCLK is generated by dividing the XTAL frequency FXOSC by

4 if CRYSTAL is ´L´ and by dividing the XTAL frequency FXOSC by 6 if CRYSTAL is ´H´.

Note: CRYSTAL is one bit of the control information.

1.3 Modulation

The SC3011 uses FSK modulation with a frequency deviation of ≈60 kHz at a gross data rate

from 18,25 kbit/s for the 868,300 MHz ISM band.

In the transmitter, the data from the pulse interference resistant protocol encoder is first trans-

formed into a complex base-band signal in the sin/cos block. After filtering it is shifted up to RF in

an I/Q based direct conversion transmitter.

1.4 Burst interference Resistant Protocol Encoder

In order to avoid disturbance due to pulsed interferes, e.g. GSM phones, the net data block is

encoded with a special protocol. Up to two simultaneous GSM disturbers can be handled by

adding redundancy to the FSK data in a suitable manner.

The 128 bits of a message (net data block) are put into a transmission sequence that alternates

a synchronization packet and data packet at transmission as shown in Figure 2.

To form a data packet, the 128 bit net data the information is split in 16 bytes where a bytenum-

ber and a parity is added to generate 14 bit words. Therefore the 128 bits of net data are ex-

panded to the 224 bit long (gross) data packet. The synchronization packet is simple 0101-

sequence of 252 bit.

Transmission Protocol

SYNC

0-1-Sequence

Data Packet

W0 . . . W15

SYNC

0-1-Sequence

Data Packet

W0 . . . W15

Word Pattern in Data Packet

W0 W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15

12.28 ms

Figure 2:

010101...

Bit Pattern for SYNC

13.81 ms

Transmission protocol of the ASCell3911.

...010101

Rev. A, February 2000

Page 4 of 13

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