Time Constant for RC Low Pass Filter in LVDT Demodulation With 5% Ripple Limit

The primary winding of an LVDT is excited by 10,000hz source , the input displacement of the core has highest frequency content of 1000 hz , the output of LVDT is connected to a phase sensitive demodulator which in turn is connected to a RC low pass(single stage) filter ,find the time constant of the filter in case the ripple due to the demodulated signal is limited to 5%.Is this arrangement satisfactory? If not , suggest a better arrangement of filter ckt.

thanks in advance