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A filings coherer changes from high to low electrical resistance following electrical excitation. A local battery supplies the readout electric current; a tap resets the detector. It records events rather than the incident radio wave waveform.

Marconi described nickel and silver filings between silver plugs, with a cell and sensitive telegraph relay controlling a tapper and recorder.^[ref]

Guglielmo Marconi developed wireless telegraphy by coordinating the transmitter, propagation and receiver as one experimental system. His lecture describes a coherer containing nickel and silver filings, connected to a tuned circuit and a relay. The relay operates a recorder and a tapper that resets the detector, allowing successive signals to be registered. Long and short wave trains encode telegraphic signs. Improving detector reliability and resonance of electrical circuits therefore mattered alongside producing radiation at the transmitter.^[ref]

A physicist.^[ref]

Wireless telegraphy links the dynamics of a transmitter, propagation and the response of a receiver. A successful detector reading depends on that complete chain, rather than on the transmitter alone.

Guglielmo Marconi's 1909 lecture describes antennas with earth connections and separate coupled receiving circuits. His 1900 system coupled a closed capacitor–inductor–spark gap loop to a transmitting antenna. Coil spacing adjusted coupling; inductance and capacitance adjusted tuning. All four circuits were tuned together. By 1909 his company's stations mainly used magnetic receivers, rather than coherers.^[ref]

Those are a participant's retrospective descriptions, not a complete account of priority. An earth connection is part of this antenna arrangement; it is not a universal requirement for radio communication. Nor does tuning an isolated LC circuit ensure that its frequency remains unchanged when strongly coupled to another circuit. The coupled resonant circuit model quantifies that distinction.