It used to happen frequently that one electronic product would interfere with another. One EMC Standards Report by consultancy Cherry Clough, details incidents where uncontrolled emissions resulted in unhelpful outcomes. It tells of a bathroom fan that activated a security light which, in turn, activated an alarm clock; helicopters that tribocharge during flight release arcs of electricity on approach to an offshore metal landing platform, causing local computer systems to fail; and travel trays, designed to keep food and drink from sliding around, wiping the data on laptop computers. Sadly, the impact of such interferences can be tragic.
This once common feature is caused by a leakage somewhere in the device and labelled as emissions. Legislation has defined what is acceptable for electronic goods to emit and this, formally recognised by certification, is what products destined for sale need to adhere to.
BitBox has acquired a shielded EMC (Electromagnetic Compatibility) chamber to help test products being designed and manufactured in house with a range of EMC techniques. The chamber is a steel-clad room designed to enable the testing of equipment while minimising outside interference; your mobile phone (or any telecommunications device) will not work once inside the chamber, similarly, a nearby active mobile phone’s radiation cannot skew the results of a test. This gives remarkable insight in to the integrity of a product under development.
Tests undertaken by the BitBox compliance team identify the mains conducted emissions and the radiated emissions of any electronic device being manufactured. It is possible to also test for conducted immunity.
Devices that are powered by mains electricity are tested for conducted emissions. During these tests, a Line Impedance Stabilisation Network (LISN) device is used to create a known impedance and isolate any unwanted noises to allow the spectrum analyser, or EMI (Electromagnetic Interference) receiver, to take accurate readings.
For the second test, high gain antennas are used to pick up noise from the equipment. The sensitivity of these antennas is great, so much so that a screened bulkhead in the chamber wall eliminates the possibility of additional frequencies being detected. The data is sent to a spectrum analyser, which uses a range of EMI filters and software to produce charts for analysis.
If an issue is identified, the equipment can be modified to pinpoint the cause, even down to a single component. In these situations, design engineers can be brought back in to investigate the possible sources of failure.
Compliance Manager at BitBox Tim Scott said “We understand the value and importance of an overview of EMC when designing a product from as early in the stage as the FSD [Functional Specifications Document].
“A lack of good EMC techniques can make the difference between a product that gets to the client on time and budget and one that is delayed with more problems than anticipated.
“We believe a holistic approach when understanding your product, helps to identify early EMC design considerations that we can readily adapt to.”
This capability brings significant benefits to the work undertaken. Products that require compliance to regulations can be tested early in the design and development, a process that reduces the cost of redevelopment if issues are identified. When issues do arise, the BitBox way of working ensures that the causes and resolutions are documented to improve future development lead times.
Ultimately, our customers are provided with devices that can be trusted, are reliable and are of a quality that testify to the reputation that we have nurtured for over two decades.