[Discuss-gnuradio] The format of I/Q sample

[xi yang]

Hi, all

I want to use fpga to do FFT before the data are transmitted to usb. 
In FFT module, I used float point numbers to be its input. According to the IEEE Floating-Point Standard, a float point number is represented by 32 bits (bits 0 through 22 form the mantissa, bits 23 through 30 form the exponent, and bit 31 is the sign bit). However, in GNU Radio, the UHD drive sends 16bits I, and 16bits Q. 
Are I and Q float point numbers? How do the 16bits represent a float number? Any suggestion about the I/Q's format is appreciated!

Thanks,
Yooxi