playing with radio waves

the walkie talkie I have on channel 1 broadcasts on 462.534 Mhz (accoring to the RTL-SDR I have)

set the mode to "narrow FM"

1: 462.534.3 Mhz

2: 462.559.7 Mhz

3: 462.584.5 MHz

to get real frequency, add 28.2 to these numbers.

I looked up the real numbers, and my SDR seems to be out of tune by 28.2 KHz