| Author |
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Al Clark
Guest
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 Posted:
Wed Jan 05, 2005 7:31 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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"siddharth.vaghela@gmail.com" <siddharth.vaghela@gmail.com> wrote in
news:1104931947.313181.31420@c13g2000cwb.googlegroups.com:
| Quote: | thank u very much for all th replies :)
well ive read thru all and decided to take a few pointers from each.
mainly im doing wht i was doing earlier as well:
1. try different small but efficient and thorough implementations of
basic stuff like convolution, bit reversals, etc.
2. also have finished three different programs dealing with FFTs . now
i am working on a radix 4 FFT program.
3. besides these programming experiments, i have to go thru my projects
dealing with jpeg2000 and make sure i am perfectly clear with my
analysis of wht i did.
4. go thru some fixed point arithematic
5. since the position is inclined towards image processing work, ill
concentrate mainly on dsp fundamentals related to multi-dimensional
analysis.
6. my USP as such is the combination of project + academic knowledge of
DSP, image processing, DSP based programming, Wavelets and computer
graphics. i am pretty strong with the fundamentals in these areas.
does tht sound like a good USP?
thankx once again for all the help. i am usually confident abt wht i
have done. but i do get tired and then the brain goes blank. so ill try
to keep my stamina going so tht i can be confident thruout the long
process.
siddharth
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Go get 'em!
--
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com |
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Charles Krug
Guest
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| Posted:
Wed Jan 05, 2005 7:38 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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On 4 Jan 2005 06:55:08 -0800, siddharth.vaghela@gmail.com
<siddharth.vaghela@gmail.com> wrote:
| Quote: | hello,
i am going to interview with a embedded systems company with focus on
DSP based applications. what kind of questions can i expect from field
of dsp and embedded systems? i have completed my masters in electrical
engineering.
if anyoen knows some good questions asked, please let me know. the
answers i can find for myself :)
siddharth
|
When I was last interviewer, rather than eee, we were looking for
applications people. This didn't require much esoteric DSP knowledge so
much as strong programming and problem solving.
By the time they got to me, it was established that 1, their resume
wasn't pure BS and 2, they knew enough C and enough of one assembler to
get by--if they were hired, they'd learn two assembly languages within a
month, and more about embedded systems than they realized was possible
to know.
After a few preliminaries I'd ask:
"How many gas stations are there in this town?"
I'm more interested in the process than the answer, which I didn't
happen to know.
"My sister has five boys. She can't see the living room from the
kitchen. When she does the dishes, she's doesn't want to leave them
unsupervised, so she checks them every five minutes. How would you
suggest she improve that process? What are the drawbacks to your
suggestion?"
The first part is (hopefully) obvious. If it isn't, the candidate will
have problems. The second is the difference between a "programmer" and
an "Engineer." |
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Randy Yates
Guest
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| Posted:
Wed Jan 05, 2005 8:40 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Charles Krug <cdkrug@worldnet.att.net> writes:
| Quote: | [...]
"How many gas stations are there in this town?"
The first part is (hopefully) obvious.
|
Could you enlighten me? I couldn't begin to tell you how I would
answer such a question when visiting a strange town, thus my answer
would be, "I don't know."
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124 |
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glen herrmannsfeldt
Guest
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| Posted:
Wed Jan 05, 2005 10:07 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Randy Yates wrote:
(snip regarding technical job interviews)
| Quote: | I agree completely with all these Jerry. But have you noticed
there are many who would place image above real capability? Thus
the slick-talking, sharp-looking young college guy wins out over
the short, slow-but-steady talking young college guy (or girl).
|
Have you noticed it also works that way for elections?
-- glen |
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Tim Wescott
Guest
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| Posted:
Wed Jan 05, 2005 11:41 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Randy Yates wrote:
| Quote: | Jerry Avins <jya@ieee.org> writes:
[...]
"I don't know" is better than bullshit. "I don't know, but I can guess"
is better yet. Almost as good as knowing is "I don't know, but I know
how to find out."
I agree completely with all these Jerry. But have you noticed
there are many who would place image above real capability? Thus
the slick-talking, sharp-looking young college guy wins out over
the short, slow-but-steady talking young college guy (or girl).
|
But -- do you really want to work with a bunch of "engineers" who got
their jobs by their slick-talking capabilities?
For a long time I've been working at a company where I was the
"technical" part of the interview. I usually asked just two questions
per interview:
1: "Tell me about a project that you liked and have completed
recently". I look for the interviewee to show that they understand what
they did, that they actually contributed to the project, and that they
can communicate what they did.
2: I pose them a technical problem with enough ramifications to
investigate their math skills, their coding or circuit design skills,
and their ability to work with in cost/time constraints (i.e. for an
embedded SW engineer I would ask a question that culminates in doing
fractional math without floating point support, for an EE I may ask
something that results in a voltage regulator, or a snazzy digital circuit).
These questions usually take 90 minutes to two hours to answer, and are
best done by a small panel of interviewers, to gather perceptions from
different points of view. It drives HR up the wall because they want
something that is _absolutely objective_ so someone can't come back
later and claim that they didn't get hired because of race, color,
perceived gender preference, whatever. I feel that you _can_ be
reasonably objective in such circumstances -- but then I wasn't the one
worried about getting sued.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com |
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Cory
Guest
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| Posted:
Wed Jan 05, 2005 11:59 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Randy Yates wrote:
| Quote: | Charles Krug <cdkrug@worldnet.att.net> writes:
[...]
"How many gas stations are there in this town?"
The first part is (hopefully) obvious.
|
Since Charles also does not know the "correct" answer, I guess he wants
a way to find out how many there are. You could drive around town, but
that's not very efficient, the phone book might be a good place for an
estimate.
About the sister and her children, that one's tougher. Perhaps she
should only do the dishes when there is another adult present. We
don't know any information about the ages of the kids only that they
are all boys. Given that she is worried about them alone for even 5
minutes suggests that they must be very young--so maybe a playpen in
the kitchen would suffice. |
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Jerry Avins
Guest
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| Posted:
Thu Jan 06, 2005 12:06 am Post subject:
Re: need interview questions for a DSP based embedded system |
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Tim Wescott wrote:
...
| Quote: | For a long time I've been working at a company where I was the
"technical" part of the interview. I usually asked just two questions
per interview:
1: "Tell me about a project that you liked and have completed
recently". I look for the interviewee to show that they understand what
they did, that they actually contributed to the project, and that they
can communicate what they did.
|
Yup!
| Quote: | 2: I pose them a technical problem with enough ramifications to
investigate their math skills, their coding or circuit design skills,
and their ability to work with in cost/time constraints (i.e. for an
embedded SW engineer I would ask a question that culminates in doing
fractional math without floating point support, for an EE I may ask
something that results in a voltage regulator, or a snazzy digital
circuit).
|
One I like is an ideal one-henry inductor, one end grounded, in parallel
with a 40-volt neon bulb (youngsters: think Zener diode). A battery
supplies one amp through a resistor to the inductor, steady having been
reached when it is disconnected at t=0. Describe the subsequent current
in the inductor.
What I like about it is that it's easy, but the solution requires
fluency with fundamentals.
...
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Guest
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| Posted:
Thu Jan 06, 2005 12:31 am Post subject:
Re: need interview questions for a DSP based embedded system |
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|
I'll bite Jerry. If we're talking symbolically, then i don't see a
problem. If, however, we're talking about L as an inductor and Z as
impedance, then i believe that you have left out the phasor
relationship (lag for an inductor?). Therefore, the voltage and
current cannot simply be divided.
I'd struggle with this question though, because i've forgotten most of
this stuff. So no laughing from me then.
[snipped]
| Quote: | I like to ask Masters and PhDs in EE if this seems strange:
Z = v/i
v = L*di/dt
i = sin(wt)
di/dt = w*cos(wt)
v = L*w*cos(wt)
Z = L*w*cot(wt)
Some can't find the error, a very few contend there isn't one. I
usually
end up hiring the ones who laugh as soon as I write it down. |
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Jon Harris
Guest
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| Posted:
Thu Jan 06, 2005 1:02 am Post subject:
Re: need interview questions for a DSP based embedded system |
|
|
"Charles Krug" <cdkrug@worldnet.att.net> wrote in message
news:IZSCd.68974$uM5.56595@bgtnsc05-news.ops.worldnet.att.net...
| Quote: | On 4 Jan 2005 06:55:08 -0800, siddharth.vaghela@gmail.com
siddharth.vaghela@gmail.com> wrote:
"My sister has five boys. She can't see the living room from the
kitchen. When she does the dishes, she's doesn't want to leave them
unsupervised, so she checks them every five minutes. How would you
suggest she improve that process? What are the drawbacks to your
suggestion?"
|
My first thought would be to change from the current polled system to an
interrupt-driven system. If audio alone would suffice, then a baby monitor
would allow this, unusual audio activity (loud sounds or complete silence!)
being used to interrupt the dish washer. Our ears work more like interrupts,
allowing us to hear things even though we aren't listening specifically for
them, while our eyes are more liked a polled system, where you have to
intentionally look at something to perceive it (lightening, etc. being somewhat
of an exception). |
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Tim Wescott
Guest
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| Posted:
Thu Jan 06, 2005 1:33 am Post subject:
Re: need interview questions for a DSP based embedded system |
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cb135@hotmail.com wrote:
| Quote: | I'll bite Jerry. If we're talking symbolically, then i don't see a
problem. If, however, we're talking about L as an inductor and Z as
impedance, then i believe that you have left out the phasor
relationship (lag for an inductor?). Therefore, the voltage and
current cannot simply be divided.
I'd struggle with this question though, because i've forgotten most of
this stuff. So no laughing from me then.
[snipped]
I like to ask Masters and PhDs in EE if this seems strange:
Z = v/i
v = L*di/dt
i = sin(wt)
di/dt = w*cos(wt)
v = L*w*cos(wt)
Z = L*w*cot(wt)
Some can't find the error, a very few contend there isn't one. I
usually
end up hiring the ones who laugh as soon as I write it down.
The error is in not understanding that the convention for Z is that it |
uses phasor relationships (or laplacian or fourier operators). So the
error comes when you write down the last line, putting down an
expression for Z that doesn't fit the context.
At one point in my career I would have worried about a question like
this "geeze, if this guy believes it he's so out to lunch and he'll
never hire me!". Later, I realized two things: working for people who
are out to lunch and don't know it is a nightmare for the honest
engineer, and the interview process is helping you make your final
decision as much as it is helping them make theirs.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com |
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Stan Pawlukiewicz
Guest
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| Posted:
Thu Jan 06, 2005 1:59 am Post subject:
Re: need interview questions for a DSP based embedded system |
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|
Jon Harris wrote:
| Quote: | "Charles Krug" <cdkrug@worldnet.att.net> wrote in message
news:IZSCd.68974$uM5.56595@bgtnsc05-news.ops.worldnet.att.net...
On 4 Jan 2005 06:55:08 -0800, siddharth.vaghela@gmail.com
siddharth.vaghela@gmail.com> wrote:
"My sister has five boys. She can't see the living room from the
kitchen. When she does the dishes, she's doesn't want to leave them
unsupervised, so she checks them every five minutes. How would you
suggest she improve that process? What are the drawbacks to your
suggestion?"
My first thought would be to change from the current polled system to an
interrupt-driven system. If audio alone would suffice, then a baby monitor
would allow this, unusual audio activity (loud sounds or complete silence!)
being used to interrupt the dish washer. Our ears work more like interrupts,
allowing us to hear things even though we aren't listening specifically for
them, while our eyes are more liked a polled system, where you have to
intentionally look at something to perceive it (lightening, etc. being somewhat
of an exception).
I first wondered why she didn't have a dishwasher, which led to next |
thing, was to wonder since 5 is a lot if the children had the same
father, which led to wondering why the current man of the house wasn't
helping or at least the oldest child. One could at least turn on the TV
or drag the whole lot into the kitchen to help. The other thing is that
after the first two kids most households either degenerate into chaos or
become a well tuned machine so checking up on the kids is either
unnecessary or futile. There is also the whole issue of contreception
or specifically the lack of. I don't think I'd get the job, which is
just as well because the question implies that the work environment
requires servicing a lot of unecessary fire drills. If someone asked me
this question, I think I would decline if offered a job. |
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Bhaskar Thiagarajan
Guest
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| Posted:
Thu Jan 06, 2005 2:16 am Post subject:
Re: need interview questions for a DSP based embedded system |
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"Stan Pawlukiewicz" <spam@spam.mitre.org> wrote in message
news:crhkf1$ndj$1@newslocal.mitre.org...
<snipped>
| Quote: | unnecessary or futile. There is also the whole issue of contreception
or specifically the lack of. I don't think I'd get the job, which is
just as well because the question implies that the work environment
requires servicing a lot of unecessary fire drills. If someone asked me
this question, I think I would decline if offered a job.
|
He he he...I like your answer the best so far.
Cheers
Bhaskar |
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Jon Harris
Guest
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| Posted:
Thu Jan 06, 2005 2:26 am Post subject:
Re: need interview questions for a DSP based embedded system |
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|
"Stan Pawlukiewicz" <spam@spam.mitre.org> wrote in message
news:crhkf1$ndj$1@newslocal.mitre.org...
| Quote: | Jon Harris wrote:
"Charles Krug" <cdkrug@worldnet.att.net> wrote in message
news:IZSCd.68974$uM5.56595@bgtnsc05-news.ops.worldnet.att.net...
On 4 Jan 2005 06:55:08 -0800, siddharth.vaghela@gmail.com
siddharth.vaghela@gmail.com> wrote:
"My sister has five boys. She can't see the living room from the
kitchen. When she does the dishes, she's doesn't want to leave them
unsupervised, so she checks them every five minutes. How would you
suggest she improve that process? What are the drawbacks to your
suggestion?"
|
I'm sure glad you guys weren't interviewing me when I got my job! I can't
maintain my own bicycle (but I know where the nearest shop is), I couldn't
figure out Jerry's inductance/impedance question (though I had a hunch), I don't
know all the answers to Randy's questions, and I didn't much idea about the gas
stations either. Yet I remain a productive DSP engineer. :-) Oh well!
I think there is a bit of a danger in relying on "trick questions" or "puzzles"
as a primary interview means. A person might miss the "aha" and never figure it
out even if they are generally bright and have good analytical skills. I like
the questions that see how they think and communicate better. |
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Charles Krug
Guest
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| Posted:
Thu Jan 06, 2005 2:46 am Post subject:
Re: need interview questions for a DSP based embedded system |
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|
On Wed, 05 Jan 2005 15:59:06 -0500, Stan Pawlukiewicz
<spam@spam.mitre.org> wrote:
| Quote: |
I first wondered why she didn't have a dishwasher, which led to next
thing, was to wonder since 5 is a lot if the children had the same
father, which led to wondering why the current man of the house wasn't
helping or at least the oldest child. One could at least turn on the TV
or drag the whole lot into the kitchen to help. The other thing is that
after the first two kids most households either degenerate into chaos or
become a well tuned machine so checking up on the kids is either
unnecessary or futile. There is also the whole issue of contreception
or specifically the lack of. I don't think I'd get the job, which is
just as well because the question implies that the work environment
requires servicing a lot of unecessary fire drills. If someone asked me
this question, I think I would decline if offered a job.
|
Hey!! That's my SISTER . . :-) |
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Charles Krug
Guest
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| Posted:
Thu Jan 06, 2005 2:55 am Post subject:
Re: need interview questions for a DSP based embedded system |
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On 5 Jan 2005 10:59:34 -0800, Cory <coryc85@gmail.com> wrote:
| Quote: |
Randy Yates wrote:
Charles Krug <cdkrug@worldnet.att.net> writes:
[...]
"How many gas stations are there in this town?"
The first part is (hopefully) obvious.
Since Charles also does not know the "correct" answer, I guess he wants
a way to find out how many there are. You could drive around town, but
that's not very efficient, the phone book might be a good place for an
estimate.
|
iirc, Fermi was fond of this as a thought problem. The story was that
he was astonishingly good as estimating it from very little
information.
| Quote: | About the sister and her children, that one's tougher. Perhaps she
should only do the dishes when there is another adult present. We
don't know any information about the ages of the kids only that they
are all boys. Given that she is worried about them alone for even 5
minutes suggests that they must be very young--so maybe a playpen in
the kitchen would suffice.
|
Hopefully, they recognize that "check every five minutes" is a polling
process, and the interrupts . . as someone suggested, either loud sounds
or utter quiet being rather important interrupt conditions. It's
something they probably learned in school. The trick is that they've
grokked it thoroughly enough to extend it to other things.
As for drawbacks . . well, most everything has drawbacks. |
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