My new gpsdo questions

[ME]

Firstly i hope this is the rite section to post this, I have just got my BH3SAP gpsdo, I followed the instructions to set it up after 1/2 hr the display says (top line) PPb -0.2 then -0.1 and keeps changing every 10 seconds or so, The bottom line gives PWM 26119 changing to 26118, can someone tell me whats going on and is this normal?, Thanks in advance.