Sanjeev,

How far do you have to transmit this data? VLF is one option and can be transmitted with a ferrite loop in an office enviornment. In the states their is a Part 15 band that allows ANY form of modulation with a 1 watt limit (a bit stout for your application, but nice to know that you have access if you need it). The band is 160KHZ-190KHZ and FM modulation would take care of the 60hz noise problem for close in communications (near field is about 1 mile at this frequency by the way).

I have used this band for 2 way communications with a fellow amatuer radio operator who lives +30 miles away using FSK,AMTOR and Packet digital modes with great reliability and even at night with heavy static. Hope this helps.

Randy Seden-WD6ELU