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
On 1/24/11 1:19 PM, Magnus Danielson wrote:
What are you *really* trying to achieve? 1-bit ADC at the end of a noisy
channel?
I have a GPS receiver front end (sampler) that normally one tests by
running GPS signals through it, acquiring and tracking the signals and
deriving SNR estimates,
Gentlemen,
I should perhaps add that I do not wanted to express that the observed flaws
are a problem of the DDS principle itself. My guess is that it is a effect
that is due to the movement of the sampling points in conjunction with the
different quantization error scenarios for every movement.
On 1/24/11 1:41 PM, Bob Camp wrote:
Hi
Most communications systems also have constraints based on signals in
adjacent channels. That pretty much forces a solution of lots of filter
before lots of gain. Distributing both gain and filtering across multiple
stages gets you into a variety of issues
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.
Gerhard,
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. Nevertheless it is true
that the HP3325 contibutes phase noise to the measurement but
Yes, it depends. Sometimes noise lowers SNR, sometimes it improves.
A similar scheme exists to improve ADC performance. If I remember it
correctly, LTC owns a patent where they inject pseudo-noise with known
properties, then the signal runs thru the ADC, then 'a picture of' the
added input
Ahhh,
I see what you mean because a few pages later there is word of a phase
accumulator. But this phase accumulator is a part of the electronics that
is responsible for generating the control voltage of a VCO that enables the
device to produce odd frequencies despite the integer dividers in the
TimeNut folks,
A thought occurred to me that there should be a way to lock our
OCXO/TCXOs to cell phone services signals that that is present almost
everywhere. I am not conversant with cellular technology so I am curious!
Any ideas and/or thoughts?
Cheers
--
Raj, VU2ZAP
On Jan 25, 2011, at 7:25 AM, Raj wrote:
A thought occurred to me that there should be a way to lock our
OCXO/TCXOs to cell phone services signals that that is present almost
everywhere. I am not conversant with cellular technology so I am curious!
Any ideas and/or thoughts?
There are commercial radio clocks that receive the CDMA signal and use
it for timing. Here is one company and they have a write-up comparing
CDMA to GPS. Short answer, GPS works at the nanosecond level CDMA at
the microsecond level but CDMA can go through walls while GPS needs to
see the sky
Hi
Jitter from the sawtooth phase modulation on a DDS output is indeed a very
real thing. I have an Agilent 33250A generator sitting here on the bench
that makes a very nice variable jitter signal source.
Bob
-Original Message-
From: time-nuts-boun...@febo.com
Hi
Several of the big guys have tried this approach.
The problem seems to be that you are at the mercy of the guy who is
transmitting the signal. He may (or may not) be very good at keeping things
running right. Regulations may (or may not) actually require him to lock his
signal to GPS.
A
Hi
Looks like somebody grabbed it pretty fast. I wonder if they have the
hardware that goes with the manual?
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Mark Sims
Sent: Monday, January 24, 2011 8:48 PM
To: time-nuts@febo.com
What you need is the AD9913. It has a programmable modulus.
Now you're not stuck with 2^32. You can pick any convenient
value.
Rick Karlquist N6RK
On 1/25/2011 5:37 AM, Ulrich Bangert wrote:
Gentlemen,
the pros and cons of DDS chips and how to improve them have been discussed
here from time
At 11:14 AM 1/25/2011, Bob Camp wrote:
Looks like somebody grabbed it pretty fast. I wonder if they have the
hardware that goes with the manual?
I sent the ebay link to a friend with one, but I've not heard if he
bought the book.
--
newell N5TNL
At 11:24 AM 1/25/2011, Scott Newell wrote:
At 11:14 AM 1/25/2011, Bob Camp wrote:
Looks like somebody grabbed it pretty fast. I wonder if they have the
hardware that goes with the manual?
I sent the ebay link to a friend with one, but I've not heard if he
bought the book.
Oops. I just
Jim,
On 25/01/11 14:53, jimlux wrote:
On 1/24/11 1:19 PM, Magnus Danielson wrote:
What are you *really* trying to achieve? 1-bit ADC at the end of a noisy
channel?
I have a GPS receiver front end (sampler) that normally one tests by
running GPS signals through it, acquiring and tracking
Bob,
I don't know the 33250 from my own experience but after all my Stanford
Research DS345 buy on ebay may not have been the best decision in my life. At
best I can say that I learn something new every day despite being at the
childish age of 55!
Ulrich Bangert
Ortholzer Weg 1
D-27243 Gross
Well, do not feel bad. I am now in my 66th year and still learning. BTW, I
built my first DDS back around 1970. Hard to believe. About the same time
that I built my first digital filter. Used all discrete components and back
then we still called them recursive and non-recursive. We never heard the
On 25/01/11 18:12, Bob Camp wrote:
Hi
Several of the big guys have tried this approach.
The problem seems to be that you are at the mercy of the guy who is
transmitting the signal. He may (or may not) be very good at keeping things
running right. Regulations may (or may not) actually require
C'est moi. I wanted a chance to scan it before it's lost forever in the
tubes. I'll relist it as soon as I'm done (or someone can just buy it from
me for the same price.) Would be nice if the original eventually finds a
home with an NC-2001 or -2010.
The manual would probably be of some
long shot .. cantact the seller and see if the buyer would scan it ? I'd
even offer a few $'s to cover the cost of having it done.
-pete
On Tue, Jan 25, 2011 at 11:45 AM, John Miles jmi...@pop.net wrote:
C'est moi. I wanted a chance to scan it before it's lost forever in the
tubes. I'll
Since the 9913 lacks a means of low pass filtering the DAC reference it
may well suffer from significant AM noise sidebands.
With a well designed sine to square converter as required when using it
as part of an offset source like that outlined in Rick's paper (probably
desirable to reduce the
In message 4d3f06ca.8020...@karlquist.com, Richard (Rick) Karlquist writes:
What you need is the AD9913. It has a programmable modulus.
Now you're not stuck with 2^32. You can pick any convenient
value.
Isn't it more like M/N applied to DDS, than a variable MODULUS ?
As far as I know the sine
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.
Hi Bob -
Yes. But coming back to the CMOS inverter multi-stage amplifier:
Because of the absolute momentum signal level the first stages
(=amplifier) sees it operates more linear than later more saturating stages.
As long as the single one stage works linear, this stage will not change
the
Hi Magnus -
What book? This one maybe:
Gardner F M PHASELOCK TECHNIQUES Wiley Sons 1966
- Henry
Magnus Danielson schrieb:
It goes towards sine as I recall it. The gaussian noise rubs of
overtones. Gardner describes this in his PLL book. Setting up a nice
sawtooth detector is no good when
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
On 1/25/11 10:47 AM, Magnus Danielson wrote:
Jim,
On 25/01/11 14:53, jimlux wrote:
On 1/24/11 1:19 PM, Magnus Danielson wrote:
What are you *really* trying to achieve? 1-bit ADC at the end of a noisy
channel?
I have a GPS receiver front end (sampler) that normally one tests by
running
On 26/01/11 00:35, ehydra wrote:
Hi Magnus -
What book? This one maybe:
Gardner F M PHASELOCK TECHNIQUES Wiley Sons 1966
Yes, but there is later revisions of it. A classic on PLLs.
Cheers,
Magnus
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On 26/01/11 04:32, jimlux wrote:
On 1/25/11 10:47 AM, Magnus Danielson wrote:
Jim,
On 25/01/11 14:53, jimlux wrote:
On 1/24/11 1:19 PM, Magnus Danielson wrote:
What are you *really* trying to achieve? 1-bit ADC at the end of a
noisy
channel?
I have a GPS receiver front end (sampler)
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