Rf Transmitter + Antenna - Linak HC20 PCBA Technical Description

RF transmitter+antenna
The RF transmitter is actually a SI4010 but preloaded with a specific supplier software and therefor
named SI4012.
The modulation scheme is the simplest form of ASK modulation called OOK. The data bit rate is 4
kbit/s (each bit having a length of
250 us). The coding scheme is Manchester so each bit consist of a high period of 125 us
and a low period of 125 us. Thus the signal will always have a duty cycle of 50%
(constant DC component) regardless of the data content. Data is transmitted in packets.
For a more detailed description of the coding and data scheme refer to the "RF-protocol
description".
When a button is pressed and the micro controller wakes up from sleep state it starts setting up the
RF transmitter. First it send the setup package telling the transmitter the transmitting frequency
(433.92MHz), transmit power, modulation type, to use internal oscillator, how the impedance
network on the output is configured ect. Second it send a "clear FIFO" command to clear the
internal transmit buffer.
When the setup is complete, the microcontroller send the actual data package according to the RF-
protocol.
Technical description for
HC20 schematic
Side 4/7
Rev. A
Date:
2014-09-26
Init: TOP