It's not generated from a DDS. It's from a xilinx PLD,
I think the DDS is implemented inside the PLD.
Sying that is not a DDS, it's a PLD, is like saying That is not an
amplifier, it is a transistor.
But a DDS would require a DAC somewhere. Here, I see can see the trace
from the PLD pin, to
The DDs is part of the Rb loop, the PLD divides by 3 and 2, the 10 MHz is a
direct function of the XTAL. I am sure the PLD also has other functions.
Older models had a 50.255 XTAL with a DDS on the output, I think the change
occurred some time between 2000 and 2002.
Bert Kehren
In a
Hello,
El 16/11/2011 07:22, Sylvain Munaut escribió:
But a DDS would require a DAC somewhere. Here, I see can see the trace
from the PLD pin, to the LC filter to the RF connector ... and I
probed the PLD output, it's a square wave.
A good DDS does, but (as was discussed here some time ago)
...@gmail.com
Sent: Tuesday, November 15, 2011 11:12 PM
To: Time-Nuts
Subject: Re: [time-nuts] FE 5680A new version - Filtering the 10 MHz
I am trying to understand the problem with harmonics on the 10 MHz output.
If you use it to drive the external input of another instrument, it won't be
a problem, more
On Tue, Nov 15, 2011 at 10:22 PM, Sylvain Munaut 246...@gmail.com wrote:
But a DDS would require a DAC somewhere. Here, I see can see the trace
from the PLD pin, to the LC filter to the RF connector ... and I
probed the PLD output, it's a square wave.
I don't know how this device works, an
.
Hope that helps.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: Wednesday, November 16, 2011 1:26 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE 5680A new version
Hi all,
As noted somewhere on the list, the 10 MHz output of the newer version
units is less filtered than before.
The output at the internal RF connector is even worse (there is some
more filtering going on inside the DB9 itself).
I'm looking for ways to clean up that 10 MHz output, preferrably
You can add a crystal filter using a common 10 MHz crystal in series
with a low noise, high impedance amplifier. Terminate the input side
with about 50 ohms, and set the Q of the filter with the load
impedance. Since you're only worried about harmonics, the Q can be
fairly low, making the
To: time-nuts@febo.com
Sent: Tuesday, 15 November 2011, 9:46
Subject: [time-nuts] FE 5680A new version - Filtering the 10 MHz
Hi all,
As noted somewhere on the list, the 10 MHz output of the newer version
units is less filtered than before.
The output at the internal RF connector is even worse
Robert wrote:
One off the shelf or more likely out of the junk box option is to
use the filter components from a 10Mb/s ethernet card. They work
quite well but might introduce some temperature related phase shifts.
As others have pointed out here in the past, to minimize phase and
amplitude
If the problem is only harmonics (cleaning up a square wave), a simple
LC low pass filter with a cutoff midway between the fundamental and
second harmonic might be a better choice because it minimizes the
tempco-related phase shift that either a high Q filter, or one with a
cutoff near the
Hi,
If the problem is only harmonics (cleaning up a square wave), a simple LC
low pass filter with a cutoff midway between the fundamental and second
harmonic might be a better choice because it minimizes the tempco-related
phase shift that either a high Q filter, or one with a cutoff near
* This is at the RF connector : http://i.imgur.com/Bg3SK.png
That's just nasty and indescriptible.
Close in impedance discontinuity?
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I would rather say DDS generated and poorly filtered
It's not generated from a DDS. It's from a xilinx PLD, then through a
L and then through a C to the RF connector. The signal at the L output
is fairly sinusoidal (at least monotonic near the crossing), but after
the cap, it's like that ...
phase shift tempco at 10MHz ?? Butterworth?
Alan G3NYK
- Original Message -
From: David VanHorn d.vanh...@elec-solutions.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Tuesday, November 15, 2011 10:31 PM
Subject: Re: [time-nuts] FE 5680A new version
Sylvain Munaut wrote:
It's not generated from a DDS. It's from a xilinx PLD, then through an L and
then through a C to the RF connector.
The signal at the L output is fairly sinusoidal (at least monotonic near the
crossing), but after the cap, it's like that ...
While I'm waiting for my own
On Tue, Nov 15, 2011 at 4:25 PM, beale be...@bealecorner.com wrote:
Sylvain Munaut wrote:
It's not generated from a DDS. It's from a xilinx PLD,
I think the DDS is implemented inside the PLD.
Sying that is not a DDS, it's a PLD, is like saying That is not an
amplifier, it is a transistor.
In
On 11/15/11 3:06 PM, Alan Melia wrote:
Another approach to filtering is a 10.7 MHz IF filter... they're common,
fairly wide band, but not too wide. Can't say much about the tempco.
Minicircuits BLP-10.7 or BLP-15 for instance
or BBP-10.7 (which is about 2 MHz wide)
of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] FE 5680A new version - Filtering the 10 MHz
Robert wrote:
One off the shelf or more likely out of the junk box option is to
use the filter components from a 10Mb/s ethernet card. They work
quite well
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