Tobias,
To get accurate noise floor at the lower Tau you need to make sure your
delay between each channel is set to as close to zero as possible.
A variable phase shifter or various lengths of cables/connectors will
work.
Cheers,
Corby
___
Dear colleagues
As some of you may remember I built my own DMTD in December and I struggled
with some problems. It had quite a bit of stability issues.
A noise floor test with some 10 MHz sources gave a 2e-12 noise floor at
1sec, not so good!
[image: grafik.png]
Well, after I had this result,
Yes. The first page says that, along with several entries in the spec sheet.
Then, on page 6 lists absolute maximum. 12.6V (I was .1V off). To me, that's
awfully close. I chose not to go there, especially when 9V gave me what I
wanted in the first place.
In many ways and places, I've
> -Original Message-
> From: time-nuts mailto:time-nuts-boun...@lists.febo.com > On Behalf Of Charles
> Steinmetz
> Sent: Wednesday, March 25, 2020 5:23 PM
> To: time-nuts@lists.febo.com mailto:time-nuts@lists.febo.com
> Subject: Re: [time-nuts
Taka Kamiya wrote:
According to the datasheet, AD8007's absolute max is 12.5V. It's a bit scary
to go to 12V.
Not at all. Look at the first page of the datasheet, which recommends
supplies from 5v to 12v. I've deployed thousands of them running at 12v
(usually, +/- 6v) with superb
According to the datasheet, AD8007's absolute max is 12.5V. It's a bit scary
to go to 12V. I was able to reduce the gain to zero dB, and get a clean and
respectable 11.5dBm output. With this, I'm perfectly happy. I would
experiment with other changes if I had a meaningful way to measure its
On Behalf Of
>> kb...@n1k.org
>> Sent: Wednesday, March 25, 2020 9:46 AM
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] Noise Floor
>>
>> Phase noise looks pretty good. ADEV has some weird "stuff" going
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of
> kb...@n1k.org
> Sent: Wednesday, March 25, 2020 9:46 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Noise Floor
>
> Phase
;.
Bob
-Original Message-
From: time-nuts On Behalf Of Taka Kamiya via
time-nuts
Sent: Wednesday, March 25, 2020 2:49 PM
To: Discussion of precise time and frequency measurement
Cc: Taka Kamiya
Subject: Re: [time-nuts] Noise Floor
I've been playing around with Clifton amplifier as wel
Taka Kamiya wrote:
I've been playing around with Clifton amplifier as well. Mine, input is
terminated with 50 ohm register, and rest is unmodified, so it has 6dB gain. I
have a 10dB pad on input side. I, too, noticed there will be a severe clipping
with driving it too hard.* * * I
Bob
-Original Message-
From: time-nuts On Behalf Of jimlux
Sent: Tuesday, March 24, 2020 7:31 PM
To: time-nuts@lists.febo.com
Subject: Re: [time-nuts] Noise Floor
On 3/24/20 2:17 PM, John Miles wrote:
>>> It would be interesting to know what ADC was used and if there's an
>>&g
> Is there a _done_ solution to expand a Timepod to
> ~ 100 MHz, narrow-bandish is OK. I'm willing to solder,
> but I'm not ready for yet another development project.
> Not now.
A pair of double-balanced mixers driven by independent signal generators works
well. The mixer RF inputs are driven
Hi
> On Mar 24, 2020, at 7:31 PM, jimlux wrote:
>
> On 3/24/20 2:17 PM, John Miles wrote:
It would be interesting to know what ADC was used and if there's an
SDR-board out there that uses the same ADC.
>>>
>>> Uh.. I remember John telling me what ADC it was, but I forgot, sorry.
>>
> And then, getting the data reliably out of the ADC into the FPGA, and
> synchronized across multiple channels. That particular part doesn't
> guarantee the startup state of the internal pipeline.
There's a sync pin for use with the clock divider, but AFAIK it does nothing
when the divider isn't
On 3/24/20 2:17 PM, John Miles wrote:
It would be interesting to know what ADC was used and if there's an
SDR-board out there that uses the same ADC.
Uh.. I remember John telling me what ADC it was, but I forgot, sorry.
It uses four AD9265s. The TimePod used four LTC2216s, but the AD9265s
Am 24.03.20 um 20:06 schrieb Attila Kinali:
If you want an SDR like system to play with, try the
Red Pitaya?
You get 2 ADC channels 125MHz/14Bit or 128.x MHz/16 Bit,
2 DAC channels, 2 ARM CPUs, Network etc and it boots Linux when
you plug in an USB power supply. It has existing apps such as
> > It would be interesting to know what ADC was used and if there's an
> > SDR-board out there that uses the same ADC.
>
> Uh.. I remember John telling me what ADC it was, but I forgot, sorry.
It uses four AD9265s. The TimePod used four LTC2216s, but the AD9265s
support higher clock rates with
On Tue, 24 Mar 2020 18:26:28 +0200
Anders Wallin wrote:
> It would be interesting to know what ADC was used and if there's an
> SDR-board out there that uses the same ADC.
> Our experience with the Ettus radios is that although they have 2 channels
> there is a lot of cross-talk between rx1 and
Hi
Since the unit is still in warranty, I’m a bit hesitant to crack it open and
start
poking around :).
While it’s not 100% obvious, the ADC clock comes out the back and then
returns to the unit via a SMA jumper. At least in theory you *could* supply
your own clock to the unit. How well that
On 3/24/20 9:26 AM, Anders Wallin wrote:
Our experience with the Ettus radios is that although they have 2 channels
there is a lot of cross-talk between rx1 and rx2 channels, which makes a
diy SDR-based phase-meter challenging.
The early USRPs in particular (I don't have as much experience
On Tue, 24 Mar 2020 18:26:28 +0200
Anders Wallin wrote:
> The user-manual provides some details on the internals:
> http://www.miles.io/PhaseStation_53100A_user_manual.pdf
> Figure 6, page 35, would indicate that there is no analog mixing stage,
> just direct ADC.
I was in the lucky position
Hi
> On Mar 24, 2020, at 10:01 AM, Attila Kinali wrote:
>
> Hoi Bob,
>
> I see you got your hands on a PhaseStation. Color me jealous! :-)
If you recall all my grumbles, back in a bit I mentioned my pile of
ever more broken test gear. Keeping it all in repair had become so
time consuming
Thanks for posting these!
The user-manual provides some details on the internals:
http://www.miles.io/PhaseStation_53100A_user_manual.pdf
Figure 6, page 35, would indicate that there is no analog mixing stage,
just direct ADC.
Maybe it also shows the ADCs clocked at (max) 125 MHz, with some HPF
Hoi Bob,
I see you got your hands on a PhaseStation. Color me jealous! :-)
The noise floor data is impressive! For reference: Expensive DMTD
systems for metrological applications are usually at 1e-13 @ 1s
and a lot more expensive.
I see I have to pester John more on how he designed the
Hi
Sorry about dumping the text from the previous post !!! Obviously the mailer on
that
machine needs a bit of attention.
So here’s what it *should* have said:
When we are doing typical measurements on our time / frequency standards, much
of it involves measuring noise. In many ways it is
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