At home fetal Doppler

Allie
I'm 10 weeks and tried my at home fetal Doppler. At first I tested my heart rate and it was 80. I found something down where the baby would be around that was 127. At my 9 week ultrasound the heart rate was 182. I heard you can pick up the placenta or the cord or something. I've tried twice since then and can't find anything. Frustrating!