Sanoline B fetal doppler?

I have a Sanoline B fetal doppler and idk how to read baby's heart rate. I # comes up on screen but keeps changing. How do i know what the correct heart rate  is?

[LovemyKids86]

How many weeks are you?

[rachb11]

I have the same exact kind, put it in mode 2 it will always keep changing it never really stays at something because it just kinda guess how many beats per minute. Mode 3 is to just listen to the heartbeat i was wondering about it too n googled it lol. I can't remember what mode one was for though

[rachb11]

Oh also idk if you know, but if you find a heartbeat in the 80's or 90's it is yours. Lol i freaked out when i first found mine i was like why is the babys heartbeat so low!! Lol then my fiancee informed me we have 2 major veins running down there on both hips!

[angelmom324]

Thanks for replying. I was totally freaked out when i saw it in 80's and 90's, i told bd that its way too low lol. He always reassure me thou

[angelmom324]

Im 12 wks

[rachb11]

Haha yeah sometimes the little booger likes to move around right after you find them lol mine does it to me allllll the time, n actually did it to the doctor at my last appt lol usually you will need to look for 120's to 170's lol and even at almost 19w the little one is still hard for me to find sometimes