The systematic approach to system design?

Discussion in 'The Projects Forum' started by Sleone, Oct 15, 2016.

  1. Sleone

    Thread Starter New Member

    Nov 8, 2014
    I have a degree in Electronics Engineering and I understand the science and mathematics behind the components and circuits. But unfortunately I never studied how to design and implement a commercial-grade Electronics system from scratch. I want to design a communications module for a cubesat, and I am unsure where to start.

    Now beyond gathering the technical know-how, is there a systematic approach on how to manage and realise an electronics project? Its not the science I'm struggling with, its the methodology. Book recommendations would be great.
  2. Papabravo


    Feb 24, 2006
    What you want to learn is probably not available from a single book. There are two ways to get where you want to go:
    1. Watch and assist someone who knows how to do it. Then do what they do.
    2. Spend at least twice as much in time in solitary experimentation to develop the required skillset.
    nsaspook likes this.
  3. #12


    Nov 30, 2010
    Make a block diagram.
    What are you starting with? What is the definition of the signal or the requirements to be met? What do you need it to cause when it arrives? Is it a DC supply and you need to make a signal? Is it an RF signal and you need to detect it? Start really, really simple. Everything complicated is made of lots of simple parts. When you get the functions all in a row, you can work on reducing cost and complication, then safety requirements.
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    Ok, so you've observed and worked alongside someone who knows how to do it. But did you know what "it" is?

    I always start with a very detailed list of what I want it to do. While making this list,other questions will arise. Their answers become part of this list. When you can't think of anything else to add or remove, you've finished part one.

    The next part is to write down all the restrictions it will encounter. This list may change, but it is a starting point. (In fact, a major part of design is questioning your restrictions). For example, you may have 5v available to power it. But you may change this restriction later to 12v

    Then, the next step for me is to list how. How to meet each of your requirements given the restrictions. Without the documents (yes, write them down), your efforts will be aimless, without a rudder and wheel as it were.
    Sleone likes this.
  5. OBW0549

    Well-Known Member

    Mar 2, 2015
    The good news is that yes, there is a systematic approach to organizing and executing a design project. The bad news is that it has to be your systematic approach, developed by you to best suit your talents and your own ways of thinking and doing. And about the only way to develop that systematic approach is through experience-- preferably gained, as @Papabravo said, by working with or for one or more people who already know how to design things "from scratch" and learning from them.

    Although it's not oriented toward communication systems design, one book that might be helpful is Analog Circuit Design: Art, Science and Personalities by Jim Williams (ed.).
    Sleone likes this.
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
    I think that a cubesat can hardly be described as a commercial-grade product.

    As for the system design, the usual approach is to define the sytem-level requirements, create the architecture of the system, from that refine the requirements to fit each part of the system, then create architecture of the subsystems and design those. After that, test the subsystems, test the software and hardware together, then verify that all the requirements were met. Now imagine this process with several loopbacks in the "back to the drawing board" fashion, and you will eventually get to the result.

    In the requirements, you need to not only describe the desired functions, but you must consider all standards that you need to fulfill. If you don´t know which stadards those are right from the beginning, you will typically have to redesign everything after you realize you are not compliant.
    Sleone likes this.
  7. MrChips


    Oct 2, 2009
    Phase 1

    Step 1: Problem Identification
    Write a concise and precise definition (in 20 words or fewer) of the problem.

    Step 2: Write out complete device specifications, constraints and limitations.

    Step 3: Draw a block diagram using a conceptual approach.

    Step 4: Draw a timing diagram indicating the sequence of events.

    Phase 2 - comes after Phase 1 is completed.
    Sensacell and Sleone like this.
  8. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    Step 4 may take several forms. The actions may not be linear and not conducive to a timing diagram. My animatronic, for example, may do different things, some of them simultaneously, unrelated to what it has done in the past. In some cases, a state diagram may be appropriate, but even in my example would not apply. The point I take away is that a documented approach to the operation of the design is necessary.
    Sleone likes this.
  9. Sleone

    Thread Starter New Member

    Nov 8, 2014
    Thank you all for the responses. I'll check the book out and experiment with your tips.

    Its just that with labs and projects, things tend to focus more on demonstrating a concept like audio amplification or AM modulation rather than focusing on the performance of the design. They felt more like breadboard abstracts rather than complete systems.
  10. Sensacell

    Well-Known Member

    Jun 19, 2012
    I like to use what I call the "Helicopter Approach"

    1) Get in your helicopter and fly up high, study the overall system from the perspective of height and distance from the little details.

    2) Land your helicopter by one small block of the system and wrestle with the tiny details inside that block.

    3) Get back in the helicopter and go high again.

    4) Consciously repeat this process over and over as you work through the design.

    5) Do not work linearly through the system, spread your time evenly over all the blocks.

    The key is to not loose perspective at any point, every little design change can ripple through, sometimes illuminating more clever solutions.
    Negotiate small details with the big picture in mind.

    Hope this helps.
    Sleone likes this.