  A logarithm processing algorithm to measure beam transverse size and position
is proposed and preliminary experimental results in Hefei Light Source II (HLS
II) are given. The algorithm is based on only 4 successive channels of 16 anode
channels of multianode photomultiplier tube (MAPMT) R5900U-00-L16 which has
typical rise time of 0.6 ns and effective area of 0.8x16 mm for a single anode
channel. In the paper, we firstly elaborate the simulation results of the
algorithm with and without channel inconsistency. Then we calibrate the channel
inconsistency and verify the algorithm using general current signal processor
Libera Photon in low-speed scheme. Finally we get turn-by-turn beam size and
position and calculate the vertical tune in high-speed scheme. The experimental
results show that measured values fit well with simulation results after
channel differences are calibrated and the fractional part of the tune in
vertical direction is 0.3628 which is very close to the nominal value 0.3621.
