Product Development

BCD Audio are proud of their history of Product development; from its roots of developing products for other Companies to the development of the entire BCD Audio range, Mike Law is now able to assist your company with your own particular problems.

Product design

The translation of a system requirement into a real product is hard, and requires much experience to achieve in a time-limited, cost effective way. Further, the resulting product must be easy to manufacture, reliable and the material cost matched against the sales cost. So many times I have seen products that have been over-designed so the only people making money from the product is the component manufacturers! But it is a mistake to brutalise a design and remove key components as it can result in an unreliable, hard to manufacture and test design as well.

Often an ‘elegance’ test applied to the result helps decide the final design. EMC is important and must be considered from the beginning, and sometimes a ‘light-touch’ is all that is needed. Designers without the experience and ability can over-design the product, and just add cost.

I can bring my experience to your product.

Circuit board design

BCD Audio use the Proteus design suite from Labcenter Elecronics. The circuit required is CAD drawn, and parts taken from a library or created for the job. The circuit is linked to the PCB by rats-nest, and parts laid out by hand. DXF mechanical information can be imported from the mechanical design, and critical parts overlaid so the mechanical design is accurate.

All circuit boards are manually routed (auto-routers never seem to create cost effective layouts) where crosstalk and layout optimisation can be achieved. Often a decently laid out double sided board can achieve decent ground-plane performance where an auto-routed design might need four-layer. Four-layer boards are used for high speed and digital use, where the ground-plane becomes essential, and also when careful impedance control of tracks is required.

Broadcast quality performance to cross-talk and noise is not in an auto-routers capability, and clever manual routing will always win.
The CAD system produces PDF and DXF files for checking against the mechanical design and for documentation. More importantly, Gerber files for board production, BOM and Pick-place files are produced.

Surface mount prototype manufacture

BCD Audio has its own surface mount capability, which is suitable for prototype and low volume work. Custom written software directly imports the pick-place file from Proteus, eliminating the setup time generally required. More on this in another section.

Initial test and programming

Once the board is built, it is tested to ensure the power supplies are correct, and nothing is taking abnormal current. Most designs have programmable parts these days, and BCD Audio have programming adaptors for many of these.

Software integration

Many designs require software to function, and this might take most of the development time.

BCD Audio are comfortable with Silabs embedded processors, using a mix of Assembler and C code. Also Xilinx FPGAs with VHDL.

Often the priority is to prove the hardware works, and hand the design to a software team who will complete the process, and implement the functionality required. BCD Audio are happy to liaise with your software team. Sometimes an iterative process is needed, where the different teams work with each other, and BCD Audio understand this.

Circuit and board revision

While we try to produce a 100% correct design first time around, unknown factors and first stage testing nearly always finds trouble and the design will need revision. Also the first time the circuit board is married with the enclosure can highlight unforeseen trouble.

BCD Audio understand these issues, and believe in annotating and reworking the design as soon as problems arise, lest they get forgotten. Also we believe in holding off manufacture of the production design for as long as possible, to make sure all issues are identified.

Test and EMC verification

Once the prototype is working sufficiently well, the system performance is measured with decent equipment, to Industry standards. BCD Audio are used to BBC, IBA and IRT standards by which equipment used to measured against, and apply these as much as possible. We also use in-house techniques and equipment to gauge how good the EMC immunity and emissions are, based on EN55032, EN55035 and EN61000. Conducted and radiated tests should be made.

In most cases it is essential to do pre-compliance testing in an EMC test house as they will have better, calibrated test equipment, and will produce graphs indicating how much your product passes or fails by. BCD Audio can arrange and attend these sessions.

The test results should be fed back into the design, and problems eliminated. Often, BCD Audio will have sufficient knowledge and equipment to avoid a second pre-compliance session, but a retest is recommended if the product failed by a wide margin.

The example below passes conducted emissions with good margin. ( Ethernet)

This example of radiated emissions below show how things can go wrong.

Product documentation and EMC compliance test

The product should be fully documented, and production standard boards built from that documentation. The complete product should be fully tested against the product standards and checked in-house against the pre-compliance results.

A TCF ( technical construction file ) should be produced, and a test plan drawn up for a proper EMC and safety test by the test-house. The results are usually certified by UKAS, managed by the test house.

BCD Audio can arrange and attend these sessions.

CE and UKCA marks are affixed to a product. This is generally self-certified, but there is an obligation to be able to justify the compliance. This is based on the TCF, with results from the test house, and a declaration by the manufacturer or agent. Since Brexit, the UK has gone its own way with standards. Currently the requirements are the same as for the European Union CE.

CE mark, for the European Community	UK CA mark, introduced after Brexit

Countries worldwide have their own ways of doing things, generally based on the same international standards ENxxxxx, and often require the cooperation of a local agent.

This is outside the scope of BCD Audio’s expertise and requires liaison between the manufacturer and the agent.

FCC logo, for USA use.

Test and performance verification

BCD Audio have Lindos and Dscope audio test equipment, which are used for audio performance verification, against industry and unit specific standards. Video equipment can be tested for PAL, SDI-SD and SDI-HD standards.

We use Tektronix Oscilloscopes with Logic analyser if needed. These are capable to 300MHz and can save results over the network if required. Networked products are verified against Wired Ethernet and Wifi networks, with Wireshark, Web Browsers and user software.

EMC performance can be verified inside a screened chamber with a Hameg Spectrum analyser if need be.

Qualifications

Mike Law has a good degree in Electronic and Communications Engineering from Birmingham University, UK, and is a member of the Institute of Engineering Technology. ( MIET)

Mike Law is a member of the Audio Engineering society, contributes and pays attention to SC02-02 ( Standards for AES3 ) and SC05-05 ( Working group on Grounding and EMC practices).

Analogue Processing

Professional audio has been around so long that it can be overlooked. But the dynamic range of over 120dB and corresponding noise floors imply signals in the mV range are important, so that power supply and ground noise can swamp a product. Knowledge of Balanced input, output and ground referencing techniques can solve these problems. Also, the design of compressor/limiters are still needed, and can transform a communications system.

Digital Processing

Interfacing of converters, AES3, MADI, SDI and VHDL solutions have all been solved over the years. Integration of these to your product, and liaison with your software development team is within my experience.