In The Trenches
specifications that are mutually
exclusive. Marketing replies that this
is what the customer wants to buy.
If we can't provide it, someone
As you can see, specifications
are the weapons that the engineer-ing/marketing war is fought with.
Instead of arming the photon
torpedoes and targeting marketing,
what can you do when faced with
impossible target specifications?
First, calm down. Remember, marketing is not engineering. Their idea of
specifications is not the same as
yours. It's really a different word and
concept. They're simply repeating
what the customer wants. Often,
they've combined requests from different customers into a single product
and it may simply be that they
haven't reported the specifications
accurately. Remember the three laws
1. Marketing is not engineering.
2. Marketing has a potential sale.
3. Everything in marketing is negotiable.
Turn Lemons into
A/D is necessary. Price the system
with the new A/D. You may need to
create a completely new product
because the existing one can't be
modified. That may be an absurd
approach, but examine it anyway.
Try to anticipate every comment,
criticism, and observation that
marketing can make. Have a good
answer for each and every one. Then
call a design review.
In this review, explain in simple
terms what impact the requested
specifications have on the existing
product and then present your
design. Always have a workable
design to present. It may not be cost
effective or practical, but it is politically necessary. If you simply object to
the design, you'll be considered an
If you provide an alternative
design, you will be seen as a team
player. They may complain about the
cost or the delay or the form factor,
but, if you have clearly explained your
position and provided a design that
meets the specifications, you will be
seen as trying to help.
Note: You should generally just
present your new approach. Let
the questions lead you into com-
paring the new and old designs.
Non-technical people generally
find this easier to follow, but be
completely prepared with graphs,
It often happens that, during this
design review, new information or
specifications emerge. In this
example, the reason for 0.1 degree
accuracy was because the product
was to be used for measuring the
body temperature of animals in a
zoo. Since very few warm-blooded
animals have a body temperature
below 85 degrees and above 110
degrees, the eight-bit A/D can
provide the 0.1 degree resolution
required (256 steps in 0.1 degree
increments gives a 25. 6 degree
Did you notice that we're talking
resolution rather than accuracy?
They are two entirely different
Unfortunately, they are often
confused. The resolution of a system
is its ability to separate close
measurements. In this case, it's 0.1
degrees. The accuracy is the ability
to measure according to a standard.
This has not been discussed at all
Suppose you are given an
impossible task. Let's say that marketing has promised a client a product that can measure temperature
from 0 to 200 degrees F in 0.1
degree intervals using one of your
standard products that has a simple,
Unfortunately, the processor
only has an eight-bit A/D (
analog-to-digital converter). You need 2,000
steps (200 degrees by 0.1 degree
intervals) and the A/D only provides
256 steps. It's impossible to do!
(Actually, it may be possible if you
employ the statistics we discussed a
few months ago.)
First, calmly examine the
problem in detail. Then, create your
best design. In this case, let's say
that you feel that an outboard 12-bit
Circle #37 on the Reader Service Card.