Due to long service life

the train-ground communication（TGC）system of Shanghai Metro Line 2 drifts along with the change of temperature and electromagnetic environment

the inductance and capacitance of trackside frequency shift keying（ FSK） signal transceiver will drift

which will affect communication quality between train and platform

eventually resulting in late train operation

non-stop or out of the platform and other issues. In order to facilitate the staff to discover the communication problems of TGC system in time

a portable train ground communication detection device is designed to monitor and record the signal quality of TGC in real time

relationship between parameters of the measured FSK signal and resonance frequency and compensation capacitor parameters of loop communication device are found

corresponding database is established.