  A detector emulator method has been developed. It allows for testing any
readout electronics with realistic detector-like signals under controlled
conditions, beyond the limits of any experiment based on radiation sources. It
can substitute for expensive test-beam campaigns, or predict their results. The
detector emulator is a powerful tool for the engineering of detector concepts,
with its capability to reproduce any detector signal feature to test the
electronics response. Here, the method is applied to the case of the VMM3a ASIC
tested with sTGC detector emulated signals. Measurements of charge spectra and
muon detection efficiency under intense gamma background are reproduced. The
effect of different attenuation circuits is studied.
