So You Want To Be An Engineer. Ray Floyd
aspects as weight, size, performance, temperature (transit, storage, and operating), power, maintenance issues, interfaces, connectivity, compatibility with older systems, languages for displays and documentation, and any certifications or standards the product must adhere too. This is not a complete list, but it is important to note that none of the items listed designate the implementation method needed to satisfy the function. The implementation is left to the development group, allowing maximum freedom in the choice and also the possible use of new technology.
As a simple example, consider the product specification of including a removable memory device. The implementation in the Technical Specification may map this requirement into including magnetic tape, diskette, memory stick, R/W CD, or even a USB connected external storage device. In short, the implementation method is left to the developer— as long as the implementation meets the Product Specification requirements.
One important aspect of the Product Specification, often overlooked, is that the specifications must be able to be verified by Product Test, Manufacturing, and Quality. For example, for the specification to state that the equipment must operate from commercial power is not verifiable. It begs the questions, “What commercial power? What voltage or voltages? What frequency? What variation is allowable? What is the maximum current load?” In each question, national and international differences must also be recognized if the product is to be marketed internationally.
The Product Specification will normally list any standards that the product will be required to meet, for example UL/CSA safety requirements. In addition, it will list any industry standards or international standards that will be required to be met for sale of the product in countries other than the home country of the product.
As noted previously, Market Requirements and Product Specifications need to cover a wide range of product aspects, such as:
• the intended market(s)
• user description(s)
• use conditions expected to be encountered
• those to address the acceptable limits
• mean-time-to failure
• mean-time-to-repair
• required through-put
• load capacity
• temperature and humidity high and low limits
• vibration and/or impact
• sound/noise level limits
• serviceability and operational access requirements
• all documentation to be used by the product manufacturer, intended users, and those who will service and maintain the equipment
Not to be ignored are national standards established by and for industries as to their products and services. These standards must be explored when developing product and services specifications, and the test plans for their evaluation. Finally, there is the question of intellectual property, i. e., are there patents that need to be written and/or avoided, and what trademarks may be used for the final product? Intellectual property rights are a major investment for any company and can create a heavy burden on new product development efforts.
A development organization will typically be composed of a number of different engineering skills, ranging from electrical engineering to field engineering. In each case, the specialty needed will provide a portion of the final product design effort. No one specialty is any more critical than the others, but all must work together to provide the desired results - a successful product introduction.
Circuit design is most often carried out by electrical engineers. One difference in the technical approach is whether the circuits in question will be analog or digital. The difference requires different skills from the engineer. Analog circuits must be able to respond to a time varying signal, faithfully reproducing the signal of interest. In the case of the digital process, the same analog signal will be approximated by a sample process, providing a series of step values. The reproduction of the analog signal in a digital world will not be exact, but, depending on the sample rate, may approximate the signal closely enough for further processing. Some will argue that the analog signal design engineer is more of an artist, whereas the work done by digital design engineers is more scientific in nature.
Frequently, based on predicted volume sales, a complete application may be developed on a single chip — the Application Specific Integrated Chip (ASIC). The ASIC replaces many separate devices, resistors, capacitors, and similar discrete electrical parts, with the necessary mask layers on a substrate to implement the replaced physical components. Although the logic of the ASIC will typically be developed by an electrical engineer within the development group, the mask build, substrate build, and final assembly will more likely be completed by a process engineer familiar with chip manufacturing, perhaps even by an outside vendor who specializes in chip manufacturing.
Magnetic media design, whether magnetic tape, disk, or diskette, requires a mix of engineering talent. Although the principle topic is magnetic media, the reading and/or writing device must also be considered. From the media perspective, both chemical and process engineers must be involved. The material supporting the reading surface must be established, whether tape, disk, or diskette. It must be strong enough to support the movement of the media, yet pliant enough to not be damaged by handling. The material must also be capable of having the magnetic surface adhere to it, providing the magnetic media for information recording. The purity and uniformity of the surface is also critical as the bit density and speeds have increased significantly over the years.
From the perspective of the device handler, mechanical engineering and electrical engineering skills are needed. In the case of the electrical engineers, both analog and digital skills will be required to complete the product. In general, the data being read and/or written is digital information, but the magnetic media is analog in nature. As a result, the read head design lies mostly in the realm of the analog engineer, while the control and digital processing belong to the digital engineer. The skills of the mechanical engineer are called upon for the design of the movement of the read head(s) and the read head itself.
Power supply design lies primarily in the realm of the electrical engineer. In this case, the engineer must have a firm knowledge of the types of AC rectification modules, filtering, and supply loading that might be appropriate for the supply. Overload conditions, power sequencing, frequency response, input voltage variations, output loading variations, and other characteristics must meet the conditions given in the overall equipment specifications.
All of the electronics may be designed and built, but it remains to the packaging engineer, typically a mechanical engineer by skill set, to make the parts into a system. The outside covers, equipment racks, and other physical aspects of the new product must be reviewed and taken into account by the packaging engineer. Other items that may need to be considered are the packaging and shipability of the system, i.e., can the system be separated into smaller units for packing, shipping, and easier handling? Whether the system must include extra cooling, fans, heat exchangers, or water cooling options must also be considered.
Конец ознакомительного фрагмента.
Текст предоставлен ООО «ЛитРес».
Прочитайте эту книгу целиком, купив полную легальную версию на ЛитРес.
Безопасно