Set frequency and RX channel filter bandwidth (RegRxBw)
Set OokFixedThreshold (RegOokFix, default value: 0xc)
Set continuous mode (RegPacketConfig, bit 6, data processing mode)
Set bit synchronizer off (RegOokPeak, bit 5)

Set DIO mapping
    b = readSPI(RegDioMapping1);   
    bitClear(b, 5);
    bitClear(b, 4);
    bitClear(b, 3);
    bitClear(b, 2);
    writeSPI(RegDioMapping1, b);

Monitor DIO2 DATA pin (Arduino Uno Pin 7)
if digitalRead(7) returns HIGH values when there is active OOK transmission
=> increase RegOokFix value and possibly filter bw value and try again