RFM95 datasheet(46/121 Pages) HOPERF

46 / 121 page

Page 46

RFM95/96/97/98(W)

Tel: +86-755-82973805 Fax: +86-755-82973550 E-mail: sales@hoperf.com http://www.hoperf.com

WIRELESS & SENSING

PRELIMINARY

DATASHEET

Alternative OOK Demodulator Threshold Modes

In addition to the Peak OOK threshold mode, the user can alternatively select two other types of threshold detectors:

Fixed Threshold: The value is selected through OokFixedThresh

Average Threshold: Data supplied by the RSSI block is averaged, and this operation mode should only be used with

DC-free encoded data.

4.2.3.3. Bit Synchronizer

The bit synchronizer provides a clean and synchronized digital output based upon timing recovery information gleaned

from the received data edge transitions. Its output is made available on pin DIO1/DCLK in Continuous mode and can be

disabled through register settings. However, for optimum receiver performance, especially in Continuous receive mode, its

use is strongly advised.

The Bit Synchronizer is automatically activated in Packet mode. Its bit rate is controlled by BitRateMsb and BitRateLsb in

RegBitrate.

Raw demodulator

output

(FSK or OOK)

BitSync Output To

pin DATA and

DCLK in continuous

mode

DATA

DCLK

Figure 15. Bit Synchronizer Description

To ensure correct operation of the Bit Synchronizer, the following conditions have to be satisfied:

A preamble (0x55 or 0xAA) of at least 12 bits is required for synchronization, the longer the synchronization phase is the

better the ensuing packet detection rate will be.

The subsequent payload bit stream must have at least one edge transition (either rising or falling) every 16 bits during

data transmission.

The absolute error between transmitted and received bit rate must not exceed 6.5%.

RFM95 Datasheet(PDF) 46 Page - Shenzhen Hope Microelectronics Co., Ltd.