Soory,
but you are writingwrote over freqouency & what kind of RFID is used in...
The working frequency can you measure_ you need a "measuring coil"/antenne or a GDO, if you have a little bit smaller amplitude on your generators output (in Sweep modus) at some Freyuency_maybe at 13.56MHz,(for cheap cards isnot real, that have 125 KHz selekted, but is real possible that their is not a standart freyuency in system..), than you have it, but for know; what kind a chip ics are used_you MUST SEE (or konw it from documentations) THE bar CHIP inside your card...
It is not a simple job_practically inpossible....
K.