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Best DDS sig gen card

M

Mark Boroughs

Jan 1, 1970
0
I need a software driven DDS card, or external PC module, that will do
GUI (drag point style) arbitrary waves, plus mixing, AM, FM and phase
modulation of at least five or more internally generated
frequencies/waveforms in the 0.1Hz to 10MHz range. Acquisition of
external signals is not required.

Can anyone advise on a specific (and cost effective?) product that
will do this?

Regards,

Mark Boroughs
 
R

Rene Tschaggelar

Jan 1, 1970
0
Mark said:
I need a software driven DDS card, or external PC module, that will do
GUI (drag point style) arbitrary waves, plus mixing, AM, FM and phase
modulation of at least five or more internally generated
frequencies/waveforms in the 0.1Hz to 10MHz range. Acquisition of
external signals is not required.

Can anyone advise on a specific (and cost effective?) product that
will do this?


That almost calls for a selfbuilt solution.
A DDS is quickly done, and 5 of them fit
nicely into an FPGA.
Just add a DAC and you're there.

Rene
 
J

Joerg

Jan 1, 1970
0
Hello Rene,

That almost calls for a selfbuilt solution.
A DDS is quickly done, and 5 of them fit
nicely into an FPGA.
Just add a DAC and you're there.

Well, sure it can be built quickly. But then there are those jobs that
many of us dread such as creating a reliable USB interface and writing
the GUI and control software.

Mark, I suppose this might be above the price line you had in mind but
these guys make such generators:
http://www.tti-test.com/products-tti/text-pages/gen-tg4001.htm

This might be interesting:
http://www.ar.com.au/~softmark/page37.html

As to AM/FM/phase and all that I don't know if there is enough market.
Maybe these things come with flexible enough SW. I don't know Softmark
but you might just want to contact them about it.

Regards, Joerg
 
D

dlharmon

Jan 1, 1970
0
Joerg said:
Well, sure it can be built quickly. But then there are those jobs that
many of us dread such as creating a reliable USB interface and writing
the GUI and control software.

Mark, I suppose this might be above the price line you had in mind but
these guys make such generators:
http://www.tti-test.com/products-tti/text-pages/gen-tg4001.htm

This might be interesting:
http://www.ar.com.au/~softmark/page37.html

As to AM/FM/phase and all that I don't know if there is enough market.
Maybe these things come with flexible enough SW. I don't know Softmark
but you might just want to contact them about it.

Regards, Joerg

I don't think the AD DDS parts will do much other than FSK.

I did an FPGA based arbitrary waveform generator that had all the
pieces needed to make a DDS generator with AM/SSB/FM/phase. It is
actually possible to modulate the arbitrary waveform onto a carrier. It
uses 10% of an XC3S400 plus 14 of the 16 blockrams (for the 16384 point
ARB table). It works quite nicely, but I never did make a nice
interface for it. It was a senior design project from my BSEE degree. I
have been meaning to put the verilog up on the net, but never have.
Send me an email if you are interested in it. I used the CORDIC
algorithm for the mixer.

The paper I submitted is at http://dlharmon.com/~dlharmon/arb.pdf (2.6
MB PDF).
 
J

Joerg

Jan 1, 1970
0
Hello Darrell,
I don't think the AD DDS parts will do much other than FSK.

Most are just used as simple frequency generators.

I did an FPGA based arbitrary waveform generator that had all the
pieces needed to make a DDS generator with AM/SSB/FM/phase. It is
actually possible to modulate the arbitrary waveform onto a carrier. It
uses 10% of an XC3S400 plus 14 of the 16 blockrams (for the 16384 point
ARB table). It works quite nicely, but I never did make a nice
interface for it. It was a senior design project from my BSEE degree. I
have been meaning to put the verilog up on the net, but never have.
Send me an email if you are interested in it. I used the CORDIC
algorithm for the mixer.

Thanks for the offer by I don't need a DDS card right now. Mark, the
original poster might.

The paper I submitted is at http://dlharmon.com/~dlharmon/arb.pdf (2.6
MB PDF).

Nice web site. This particular PDF didn't load, always stopped with a
blank sheet. Your spectrum analyzer project could be interesting. There
should be a significant market if it could be realized without the parts
you mentioned as being prohibitively expensive. Currently there is no
"faceless" PC-based spectrum analyzer I know of that covers the usual
EMC band and can be connected via USB.

Regards, Joerg
 
J

Joel Kolstad

Jan 1, 1970
0
Hi Joerg,

Joerg said:
Your spectrum analyzer project could be interesting. There should be a
significant market if it could be realized without the parts you mentioned
as being prohibitively expensive. Currently there is no "faceless" PC-based
spectrum analyzer I know of that covers the usual EMC band and can be
connected via USB.

My suspicion for awhile has been that Agilent, Tek, and R&S aren't
particularly interested in that market because the revenue would be so much
less.

What frequencies do you consider to be "the usual EMC band?" Up to ~3GHz? Or
lower?

---Joel
 
J

Joerg

Jan 1, 1970
0
Hello Joel,

My suspicion for awhile has been that Agilent, Tek, and R&S aren't
particularly interested in that market because the revenue would be so much
less.

Well, yes, and that's why I thought that the 2nd tier companies would
jump on the opportunity. All you have to provide is a plastic box with a
BNC jack on one side and a USB jack on the other, some electronics in
the middle and a nice SW package.

What frequencies do you consider to be "the usual EMC band?" Up to ~3GHz? Or
lower?

150kHz through 1GHz suffices for most EMC work and it doesn't need a
dynamic range from here to the Klondike. There also isn't much of a need
to go below the 9kHz CISPR bandwidth which should make it even less
expensive. Frequency stability is not that important either.

Some people think that an EMC analyzer should be able to detect FM or TV
modulation to distinguish between "real" EMC problems and spoofers. But
after a couple decades on the beat I have to say that ain't so, we know
how to waive our hands to figure that out :)

Regards, Joerg
 
F

Fred Bartoli

Jan 1, 1970
0
Joerg said:
Hello Joel,



Well, yes, and that's why I thought that the 2nd tier companies would
jump on the opportunity. All you have to provide is a plastic box with a
BNC jack on one side and a USB jack on the other, some electronics in
the middle and a nice SW package.



150kHz through 1GHz suffices for most EMC work and it doesn't need a
dynamic range from here to the Klondike. There also isn't much of a need
to go below the 9kHz CISPR bandwidth which should make it even less
expensive. Frequency stability is not that important either.

Some people think that an EMC analyzer should be able to detect FM or TV
modulation to distinguish between "real" EMC problems and spoofers. But
after a couple decades on the beat I have to say that ain't so, we know
how to waive our hands to figure that out :)

Hameg had a small box exactly like that (with a bonus CRT :). I think it is
(was?) in the $2K range, with or without a track gen.
 
J

Joerg

Jan 1, 1970
0
Hello Fred,
Hameg had a small box exactly like that (with a bonus CRT :). I think it is
(was?) in the $2K range, with or without a track gen.

They do and it's a nice box. We bought it at my previous job and IIRC
the $2k was without the tracking generator which you don't need for EMC
work anyway. Susceptibility is done with lots more power and I typically
use a regular bench generator to drive the big amp.

However, $2k is still a lot for a device that gets banged up during
travel and the Hameg is too large if you want to fly with carry-on only.
When doing that I try not to be a space hog and cram it all into a
pilot's case. By the time the razor, several shirts and a sports jacket
has been tossed inside there ain't much space left. A little EMC pod for
the laptop would really be nice.

Regards, Joerg
 
D

dlharmon

Jan 1, 1970
0
Joerg said:
Hello Darrell,


Nice web site. This particular PDF didn't load, always stopped with a
blank sheet. Your spectrum analyzer project could be interesting. There
should be a significant market if it could be realized without the parts
you mentioned as being prohibitively expensive. Currently there is no
"faceless" PC-based spectrum analyzer I know of that covers the usual
EMC band and can be connected via USB.

Regards, Joerg

I am not sure what is happening with that PDF. I use ps2pdf to make
them and I have never had a problem. Maybe your version of Acrobat
reader doesn't like it.

If the network analyzer portion was removed, my design would be much
simpler. The FPGA could be eliminated and replaced with a digital down
converter. The only difficult or expensive parts would be the 2.15 to
3.95 GHz 1st LO and the 1st IF bandpass filter. The current filter is
machined from a block of copper. This is great for performance, but not
for cost. It may be possible to sacrifice some image rejection or go to
a more complex architecture to avoid this filter. I have heard of some
VCO designs covering nearly an octave. If not, it could be split into
bands. Of course, all of this adds complexity.

I believe the whole thing could fit on a 4x6 inch board. I may consider
doing it sometime in the future so others could assembly one. That is
assuming they are not afraid of a 176LQFP. At least there would be no
BGA FPGA. The one I am building now is just for learning purposes and
having fun. I have about $1000 in it. This is about 30% the 2 4 layer
board prototypes, 30% digikey and the rest is connectors and mechanical
bits like the case. Assuming it all works out and my time is free, it
will be a good deal, but considering my time at McDonalds pay, I could
have bought an Agilent.
 
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