Correct

超外差

/ chāo wài chā / 
Strokes

Example

As an Adjective

superheterodyne; superhet

1
Chāo
超
wài
外
chā
差
xiànquān
线圈

superheterodyne coil

2
Chāo
超
wài
外
chā
差
diànlù
电路
  
/
jiǎn
检
bō
波

superheterodyne circuit/detection