understanding how to use b-allele data and log2 data to call copy numbers

[jnaccara]

Hello,

I have two data files with the following columns:
File 1, CGH_Probe_Table: Probe Name, Chromosome, Start, Stop, Feature Number, Log Ratio.
File 2, SNP_Probe_Table: SNP ID, Probe Name, Chromosome, SNP Position, Feature number, Genotype.

My ultimate goal is to call copy numbers using this data. I am fairly new to this, so I would appreciate any help on how to calculate b-allele frequence, and then using that with the log ratio calculating copy numbers. Thanks!