How to transmit data using GFSK modulation?

I am new to this domain. I want to transmit data using GFSK modulation using GNU Radio which response to the following specifications :

Deviation : +/-2,4 kHz +0,2%
Modulation index : 2
Filter index : 0.5 BT
Bitrate : 2400 bit/s

I want to transmit this data (data is in HEXA): Preamble : 55 55

Synchro : F6 72
L-field ( data + CRC) : 20

Solution

I have based on this example of FSK transmitter, https://nccgroup.github.io/RFTM/fsk_transmitter.html so you need juste to put the value of BT equal to 0.5 to make a GFSK transmitter. And everthing works correctely.