Collins Chinese Dictionary Plus (3rd edition), 2011:
frequency [ˈfriːkwənsɪ]
n
1
[u]
[of event] 频(頻)繁性 pínfánxìng
2
[c/u]
(Rad) 频(頻)率 pínlǜ
- to increase in frequency
频(頻)率增加 pínǜ zēngjiā