Hi,
The AD9850 has a 10bit DAC. If the AD9850 does not dither the 10bit ADC
output the zero crossings for a 1MHz signal will have an aprox resolution of
2^-10*1us~1ns on average. If the lookup table feeding values to the dac has
10 address lines (just guessing, I do not see any anything on it on
I will answer to myself, as my previous email was unclear and buggy.
Actually I was just doing some order of magnitude calculations which seem
quite correct, but it is always better to dig bit more in the details. The
whole idea is to find the waveform paths that will generate a zero crossing
the
I posted a link to some plots of phase and amplitude
truncation/quantization
spurious pileups here a while back:
http://febo.com/pipermail/time-nuts/2009-October/041545.html
Even when not multiplied, the normal close in phase noise floor of
the DDS can be masked by spurs and intermods near
Gentlemen,
the pros and cons of DDS chips and how to improve them have been discussed
here from time to time. Most of the improvements have the aim to remove
spurs out of the power spectrum or to reduce the noise level. Yesterday I
run into a thing that may make it very qestionable whether DDS
In message E34BA9BA1D7340AD88EF19CDD971F3D8@athlon, Ulrich Bangert writes:
However for very precise timing a DDS may simply be unsuited.
No, it just has to be correctly designed.
For integral Hz resolution output, you want to feed it a frequency
with us 2^N(*10^M) where N is equal to the width
Don't forget that your HP3325 is DDS-based, too, so it adds its own
phase error sawtooth.
73, Gerhard dk4xp
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Don't forget that your HP3325 is DDS-based, too, so it adds its own
phase error sawtooth.
73, Gerhard dk4xp
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Very good read. Thank you for the effort and detail.
You confirmed something I have thought about but never really dove into.
Regards
Paul
WB8TSL
On Tue, Jan 25, 2011 at 9:14 AM, dk...@arcor.de wrote:
Don't forget that your HP3325 is DDS-based, too, so it adds its own
phase error sawtooth.
Betreff: Re: [time-nuts] An (unknown?) nasty feature of the
DDS principle for time nuts applications
Don't forget that your HP3325 is DDS-based, too, so it adds
its own phase error sawtooth.
73, Gerhard dk4xp
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Am 25.01.2011 15:35, schrieb Ulrich Bangert:
see page 8.6ff of the service manual to see that the HP3325 is not DDS based
but uses a Fractional N Synthesizer scheme which is something completely
different and is not prone to the described effects.
Yes, it's f-N, I must have stored that in the
On 1/25/2011 1:26 PM, Gerhard Hoffmann wrote:
Am 25.01.2011 15:35, schrieb Ulrich Bangert:
see page 8.6ff of the service manual to see that the HP3325 is not
DDS based
but uses a Fractional N Synthesizer scheme which is something
completely
different and is not prone to the described effects.
Another description of such artifacts occurs in the tutorial:
http://www.analog.com/static/imported-files/tutorials/450968421DDS_Tutorial_rev12-2-99.pdf
Bruce
Gerhard Hoffmann wrote:
Am 25.01.2011 15:35, schrieb Ulrich Bangert:
see page 8.6ff of the service manual to see that the HP3325 is not
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