 Further details are given in Volume 6 Part A (Physical Layer Specification) of the Bluetooth Core Specification V4.0.Bluetooth Low Energy uses frequency hopping to counteract narrowband interference problems.Classic Bluetooth also uses frequency hopping but the details are different; as a result, while both FCC and ETSI classify Bluetooth technology as an FHSS scheme, Bluetooth Low Energy is classified as a system using digital modulation techniques or a direct-sequence spread spectrum.