Patent ID: 7673524

Claim:
An apparatus for determining at least one characteristic of a fluid flowing within a pipe, the apparatus comprising: at least one sensing device, wherein said at least one sensing device includes a first sensor segment having a first segment polarity and being associated with a first outer portion of the pipe and a second sensor segment having a second segment polarity and being associated with a second outer portion of the pipe, wherein said first sensor segment and said second sensor segment generate sensor data responsive to the fluid flowing within the pipe; and a processing device communicated with said at least one sensing device, wherein said processing device receives said sensor data and processes said sensor data to determine the at least one characteristic of the fluid, wherein said at least one sensing device includes a plurality of sensor segments each of which include a sensor segment length, wherein when said at least one sensing device is configured to filter out acoustic signals, temperature signals and common mode signals, said sensor segment length is sized such that the relationship between said acoustic signals, said temperature signals and said common mode signals is given by ∫ 0 2 ⁢ π ⁢ ɛ ⁡ ( θ ) ⁢ ⅆ θ = 0 , wherein ε(θ) is equal to the signal power.