Interference suffered by equipment does not only occur as a result of power-supply borne disturbances or from electromagnetic disturbances generated by, and conveyed from or radiated by, other electrical/electronic equipment, nor from internal problems in other parts of the equipment.
It can also arise as a result of purely mechanical phenomena, quite independent of and unrelated to any electrical or electronic system, through the creation and building up of static electric charges leading to a subsequent abrupt discharge via a spark.
Such an electrostatic discharge (ESD) does not need to be visible or audible for an electromagnetic disturbance to be produced.
While the energy of the discharge often may be small, its short duration results in high instantaneous power levels and short intense electromagnetic bursts, with potentially significant local effects.
Amongst sensitive equipments that may be affected, are some test, measurement and detection systems.
To determine the solution, it is first necessary to find the causes, and suitably-configured logging equipment will capture detailed information on large numbers of individual interference events to enable this to be done. Such equipment with an appropriately-designed Antenna and RF Amplifier can also provide information in 3 axes on the incident electromagnetic fields, to provide additional geometric and diversity data.
For more information please see our page on EMI Investigation.