| Author |
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Jon Harris
Guest
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 Posted:
Thu Jan 06, 2005 4:01 am Post subject:
Re: need interview questions for a DSP based embedded system |
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"Charles Krug" <cdkrug@worldnet.att.net> wrote in message
news:FnZCd.69659$uM5.13052@bgtnsc05-news.ops.worldnet.att.net...
| Quote: | On 5 Jan 2005 10:59:34 -0800, Cory <coryc85@gmail.com> wrote:
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.
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Hey, I got one right! :-) |
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Randy Yates
Guest
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| Posted:
Thu Jan 06, 2005 5:17 am Post subject:
Re: need interview questions for a DSP based embedded system |
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"Jon Harris" <goldentully@hotmail.com> writes:
| Quote: | I don't
know all the answers to Randy's questions,
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Jon, I'm surprised. You've tutored me often enough!
| Quote: | and I didn't [have] much [of an] idea about the gas
stations either.
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I'm sure glad I'm not alone on that one.
| Quote: | I think there is a bit of a danger in relying on "trick questions" or "puzzles"
as a primary interview means.
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FYI, I didn't consider my questions "trick."
| Quote: | A person might miss the "aha" and never figure it out even if they
are generally bright and have good analytical skills.
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The ones I asked shouldn't require analysis - just memory. But I
still take your point. A person is likely to be very nervous and
may not be anywhere near up to par when being asked questions on
the spot.
--
% Randy Yates % "So now it's getting late,
%% Fuquay-Varina, NC % and those who hesitate
%%% 919-577-9882 % got no one..."
%%%% <yates@ieee.org> % 'Waterfall', *Face The Music*, ELO
http://home.earthlink.net/~yatescr |
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Jon Harris
Guest
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| Posted:
Thu Jan 06, 2005 7:16 am Post subject:
Re: need interview questions for a DSP based embedded system |
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"Randy Yates" <yates@ieee.org> wrote in message news:brc3tnq9.fsf@ieee.org...
| Quote: | "Jon Harris" <goldentully@hotmail.com> writes:
I don't
know all the answers to Randy's questions,
Jon, I'm surprised. You've tutored me often enough!
|
It was mainly the PSK modulator that I had no clue about since I've never worked
with one of those and don't know much about spectral efficiency. How about
posting the answers?
| Quote: | and I didn't [have] much [of an] idea about the gas
stations either.
I'm sure glad I'm not alone on that one.
I think there is a bit of a danger in relying on "trick questions" or
"puzzles"
as a primary interview means.
FYI, I didn't consider my questions "trick."
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I wasn't referring to anyone in particular here, just making a comment. |
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Randy Yates
Guest
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| Posted:
Thu Jan 06, 2005 7:59 am Post subject:
Re: need interview questions for a DSP based embedded system |
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Randy Yates <randy.yates@sonyericsson.com> writes:
| Quote: | "siddharth.vaghela@gmail.com" <siddharth.vaghela@gmail.com> writes:
thank u for the reply :)
thts wht i am doing exactly.. preparing my basics well and trying to
get my hands on simple programs on fir filters, bit reversals, etc etc.
i do get confused sometimes bcoz of the sheer size of material to be
remmbered.
thankx again
Hi Siddharth,
Here are some example DSP questions that I might ask an interviewee.
Note Fs is sample rate in these questions.
1. Under what conditions is the available bandwidth of a digital system
Fs Hz instead of Fs/2 Hz?
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When the samples are complex instead of real.
| Quote: | 2. What's the difference between an FFT and a DFT?
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The FFT is a specific implementation of a DFT that exploits
performance advantages.
| Quote: | 3. What two PSK modulation orders differ exactly by a factor of two
in spectral efficiency?
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BPSK/QPSK.
| Quote: | 4. How does polyphase filtering save computations in a decimation filter?
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It doesn't compute the output samples that are decimated.
| Quote: | 5. How does polyphase filtering save computations in an interpolation filter?
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It doesn't bother multiplying the input samples that are zero in the
convolution.
| Quote: | 6. Suppose we have a system with transfer function
H(z) = 1 / ((z - 1.1)*(z - 0.9)).
Is the system stable or unstable?
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Depends on the ROC.
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% <yates@ieee.org> % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr |
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Stan Pawlukiewicz
Guest
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| Posted:
Thu Jan 06, 2005 6:58 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Charles Krug wrote:
| Quote: | On Wed, 05 Jan 2005 15:59:06 -0500, Stan Pawlukiewicz
spam@spam.mitre.org> wrote:
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 . . :-)
|
Show your love, whatever childhood issues linger, and buy her a
dishwasher, it more sanitary, it saves time, and you can get a good one
for less than $500.00. I would be a lot more inclined to work for
someone who demonstrated some compassion and personal growth. :) |
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Jerry Avins
Guest
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| Posted:
Thu Jan 06, 2005 7:35 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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cb135@hotmail.com wrote:
| Quote: | I'll bite Jerry. If we're talking symbolically, then i don't see a
problem. If, however, we're talking about L as an inductor and Z as
impedance, then i believe that you have left out the phasor
relationship (lag for an inductor?). Therefore, the voltage and
current cannot simply be divided.
|
By convention, capital letters V and I refer to phasors and lower case
letters refer to instantaneous values. Z, impedance, is a ratio of
phasors. The very first line is wrong. Properly, Z = V/I. Slip a
falsehood into an argument and you can prove anything!
| Quote: | I'd struggle with this question though, because i've forgotten most of
this stuff. So no laughing from me then.
[snipped]
I like to ask Masters and PhDs in EE if this seems strange:
Z = v/i
v = L*di/dt
i = sin(wt)
di/dt = w*cos(wt)
v = L*w*cos(wt)
Z = L*w*cot(wt)
|
...
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Jerry Avins
Guest
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| Posted:
Thu Jan 06, 2005 8:13 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Jon Harris wrote:
| Quote: | "Stan Pawlukiewicz" <spam@spam.mitre.org> wrote in message
news:crhkf1$ndj$1@newslocal.mitre.org...
Jon Harris wrote:
"Charles Krug" <cdkrug@worldnet.att.net> wrote in message
news:IZSCd.68974$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.
|
A trick question isn't suitable for go/no-go, but it can provide insight
into thought processes. I hired a guy once who built a vacuum system to
do some of his thesis work. Stainless steel was beyond his budget, so he
used glass. Attaching a mass spectrometer required ingenuity; off hand,
one might call it impossible. The magnet alone needs two people to lift
into place, and the whole thing is cantilevered from its flange. A
support frame alone won't work because even if it were perfectly aligned
at one temperature, a cold draft might crack the class.
A rigid frame and interconnecting bellows would have been my deep-
pockets solution, but vacuum-grade 4-inch diameter bellows are made to
order. His solution was simpler. He improvised a support frame from 2x4s
and angle iron, and hung the mass spec with a yoke that straddled the
center of gravity, and counterweighted it. Then he simply bolted it to
the glass flange: no stress. Even the counterweights impressed me; I
recognized them as the cast-iron weights made for use with theater
curtains and flats. He admitted to being an amateur thespian.
He turned out to be, as I suspected he would, to be an outstanding
experimentalist. The point of a bagful of "trick" questions is giving
the interviewee an opportunity to shine with one or more of them.
Back in 1962, one of my interview questions was "How would you generate
30 watts of square wave at 100 MHz?" I didn't know. I professed
ignorance about semiconductors but opined that none were available to do
the job. Opinion confirmed. I said that I could get milliwatts from a
doorknob tube -- I knew the number then, but I've forgotten -- and maybe
a little more from a TWT, but 30 watts was out of the reach of any
device I knew. My interviewer said, "All true, but I need it. What would
you do?" I gave up. I said, "You could always synthesize it. but ..."
That's as far as I got. He grinned and said, "That's what we did!"
Good interviewers look for an indication that candidates can deal with
new problems. Some people call it "thinking outside the box". That
phrase itself comes from the "trick" question about connecting 9 dots. I
call it "To boldly go where no textbook (that I read) has gone before."
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Rune Allnor
Guest
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| Posted:
Thu Jan 06, 2005 9:22 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Jon Harris wrote:
| Quote: | "Stan Pawlukiewicz" <spam@spam.mitre.org> wrote in message
news:crhkf1$ndj$1@newslocal.mitre.org...
Jon Harris wrote:
"Charles Krug" <cdkrug@worldnet.att.net> wrote in message
news:IZSCd.68974$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.
|
Humm.... I've found this thread very interesting, and also a bit
worrying.
I've never been on the hiring side of the table in interviews, but I
know
what to look for in prospective colleagues, and I have a vague idea
about
how to search out people.
What would make me sceptical, is "great communications and people's
skills".
Imagine travelling at an airplane where the chief pilot is a great
entertainer,
knows a vast amount of people but doesn't really know how to fly the
aeroplane.
That's the situation I'll try to avoid at any cost. Being able to talk
smoothly is an advantage, but only if there is real knowledge at the
base
to substantiate what would otherwise be mere noise.
I'll agree with those who present a difficult/impossible problem, and
see how the interviewee handles it. I would prefer, though, to keep
the question within the "professional scope".
Rune |
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Randy Yates
Guest
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| Posted:
Thu Jan 06, 2005 9:51 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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"Rune Allnor" <allnor@tele.ntnu.no> writes:
| Quote: | [...]
I'll agree with those who present a difficult/impossible problem, and
see how the interviewee handles it. I would prefer, though, to keep
the question within the "professional scope".
|
I'm still waiting to see how one divines the number of gas stations
in a strange town...
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124 |
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Jerry Avins
Guest
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| Posted:
Thu Jan 06, 2005 10:33 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Randy Yates wrote:
| Quote: | "Rune Allnor" <allnor@tele.ntnu.no> writes:
[...]
I'll agree with those who present a difficult/impossible problem, and
see how the interviewee handles it. I would prefer, though, to keep
the question within the "professional scope".
I'm still waiting to see how one divines the number of gas stations
in a strange town...
|
From one source or another, ask. Yellow pages?
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Rune Allnor
Guest
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| Posted:
Thu Jan 06, 2005 11:21 pm Post subject:
Re: need interview questions for a DSP based embedded system |
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Randy Yates wrote:
| Quote: | "Rune Allnor" <allnor@tele.ntnu.no> writes:
[...]
I'll agree with those who present a difficult/impossible problem,
and
see how the interviewee handles it. I would prefer, though, to keep
the question within the "professional scope".
I'm still waiting to see how one divines the number of gas stations
in a strange town...
|
Eh... I'm not sure if "divines" is a typo or not, I don't know
the word so I interpret is as "estimates".
Around here, the gas stations tend to be clustered around the
main highways where these enter town. The gas stations usually
come in pairs, with a compeptitor building across the road once
somebody have built a first station. So as a first estimate, find
the number of main road entrance points in a town, multiply by two
to accound for clusters, and multiply by two once more to account
for those gas stations that were already present before this
"main road clustering effect" became significant.
What the numbers are concerned, one might just as well roll
a handfull of dice. However, one gets the impression it's a
semi-coherent line of quasi arguments, if only rudimentary.
At best.
I'm not sure I would have accepted a job offer if my ability
to come up with ga-ga as above, was the factor that tipped the
scale in my direction... Nah, get me a question about how to
correct for various types of geology in the sea bed when
searching for oil and gas.
Rune |
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Jerry Avins
Guest
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| Posted:
Fri Jan 07, 2005 2:20 am Post subject:
Re: need interview questions for a DSP based embedded system |
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Rune Allnor wrote:
...
| Quote: | Eh... I'm not sure if "divines" is a typo or not, I don't know
the word so I interpret is as "estimates".
|
"Determines" would be better. A "divining rod" is a tool often used for
dowsing.* ) I suppose without checking that the word derives from the
holy men who predicted the outcomes of battles by examining the entrails
of birds or sheep. ;-] I make no representation about the efficacy of
these practices.
Jerry
________________________________________________
*See http://www.diviningmind.com/
http://web.telia.com/~u56302584/dowsing.htm, and
http://www.leyman.demon.co.uk/Dowsing.html.
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Randy Yates
Guest
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| Posted:
Fri Jan 07, 2005 2:43 am Post subject:
Re: need interview questions for a DSP based embedded system |
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Jerry Avins <jya@ieee.org> writes:
| Quote: | Rune Allnor wrote:
...
Eh... I'm not sure if "divines" is a typo or not, I don't know
the word so I interpret is as "estimates".
|
No, it was not a typo. I meant it in the sense of "to acquire knowlege
of through supernatural means."
| Quote: | "Determines" would be better. A "divining rod" is a tool often used for
dowsing.
|
Yes, along those lines.
We're being bitingly sarcastic, though. Perhaps Charles meant to ask
"How would you find out how many gas stations are in this town.". Or
perhaps the right answer to the question is, "I don't know," i.e.,
it's a BS detector question.
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124 |
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john
Guest
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| Posted:
Fri Jan 07, 2005 5:07 am Post subject:
Re: need interview questions for a DSP based embedded system |
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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
|
I have been surprised to find out how many new grads don't know how
to write a simple C program, so I always require C proficiency to be
demonstrated. I'm aware of some prestigous engineering schools
that graduate EEs with no C exposure whatsoever. Instead they know
Java, C#, etc. Nice, but no use to me.
John |
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Rune Allnor
Guest
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| Posted:
Fri Jan 07, 2005 8:01 am 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:
Rune Allnor wrote:
...
Eh... I'm not sure if "divines" is a typo or not, I don't know
the word so I interpret is as "estimates".
No, it was not a typo. I meant it in the sense of "to acquire
knowlege
of through supernatural means."
"Determines" would be better. A "divining rod" is a tool often used
for
dowsing.
Yes, along those lines.
We're being bitingly sarcastic, though. Perhaps Charles meant to ask
"How would you find out how many gas stations are in this town.". Or
perhaps the right answer to the question is, "I don't know," i.e.,
it's a BS detector question.
|
Thank you both for enlightening me of the subtleties of the English
language. As a BS detector, the question actually makes some sense.
Well, if anything, this thread has convinced me to stick with the
"professional scope" questions.
Rune |
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