] Sound Cards for locking to GPSDO 10
MHz references
One of the main problems is that in working at milli-Hz
binwidths the
FTT word length needs to be very long to cover even a few
tens of Hz
range and we run into memory problems.
I'm missing something. How much memory do you
Alberto di Bene skrev:
Magnus Danielson wrote:
Hmm, do you get a feeling that I am actually object very much to just
toss it into the processor. I think you are right. :)
I suppose you are familiar with the old American adage that says that to
a man with
a hammer every problem looks like
Lux, James P skrev:
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Rex Moncur
Sent: Tuesday, June 02, 2009 3:06 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Sound Cards for locking to GPSDO
connie.marsh...@suddenlink.net said:
www.k5cm.com/soundcard.htm
Nice, thanks.
From there:
Sound card drift over this four hour period is about 250 micro Hertz.
The temp in the shack was going up during the measurement period.
Unfortunately I did not track the exact temp rise, but was about
One of the main problems is that in working at milli-Hz binwidths the
FTT word length needs to be very long to cover even a few tens of Hz
range and we run into memory problems.
I'm missing something. How much memory do you have on your laptop?
I'm not a DSP wizard. If you have 10 Hz
There is an overbeleif in what software is suitable for IMHO.
[Fun discussion. Thanks.]
Many years ago, somebody on the FPGA newsgroup pointed out that, in general,
if you can do the problem in software that's probably the better way. One of
the considerations is that it's easier to hire
-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Hal Murray
Sent: Wednesday, June 03, 2009 12:24 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sound Cards for locking to GPSDO 10 MHz
references
connie.marsh...@suddenlink.net
Brian Kirby skrev:
I use a Lynx One sound card, it has analog and digital I/O and MIDI I/O
and clock I/O. Their manuals are available on line at
www.lynxstudio.com. These are profession 24 bit cards, the analog I/O
uses balanced interfaces. They handle AES/EBU and SP DIF digital audio
You could always transform this from a hardware problem to a software
problem. Take the output of your GPSDO, divide it down to somewhere
inside the audio band, feed it to a spare input on your USB sound
card and have software track this reference and correct the received
signal.
JDB.
--
Lux, James P skrev:
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Rex Moncur
Sent: Monday, June 01, 2009 3:00 PM
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] Sound Cards for locking to GPSDO 10
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson
Sent: Tuesday, June 02, 2009 10:08 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sound Cards for locking to GPSDO 10
MHz
J.D. Bakker wrote:
You could always transform this from a hardware problem to a software
problem. Take the output of your GPSDO, divide it down to somewhere
inside the audio band, feed it to a spare input on your USB sound
card and have software track this reference and correct the received
Hello The Net:
For portable operations with a laptop, usually only one input channel is
available
and it is at mike (not line) level.
The alternative to sum the analog reference and the analog signal of
interest may be
possible if the reference noise can be kept out of the signal of
Lux, James P skrev:
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson
Sent: Tuesday, June 02, 2009 10:08 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sound Cards for locking
Alberto di Bene skrev:
J.D. Bakker wrote:
You could always transform this from a hardware problem to a software
problem. Take the output of your GPSDO, divide it down to somewhere
inside the audio band, feed it to a spare input on your USB sound card
and have software track this reference and
Magnus Danielson wrote:
No need to switch on the soldering iron...
Never do in hardware what can be done in software :-)
Respectfully I disagree. There are tasks which is better managed by
software and tasks which is better managed by hardware. In the world of
FPGAs, it is also worth
Alberto di Bene skrev:
Magnus Danielson wrote:
No need to switch on the soldering iron...
Never do in hardware what can be done in software :-)
Respectfully I disagree. There are tasks which is better managed by
software and tasks which is better managed by hardware. In the world
of
Magnus Danielson wrote:
Hmm, do you get a feeling that I am actually object very much to just
toss it into the processor. I think you are right. :)
I suppose you are familiar with the old American adage that says that to a man
with
a hammer every problem looks like a nail :-)
Each of
Hi all
Thank you all for you advice and suggestions re my request. At this stage
it does not look like there is a simple solution of a readily available USB
sound card that can be locked to a 10 MHz GPSDO reference.
The constraints of portable operation with a Laptop rule out a number of
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Rex Moncur
Sent: Tuesday, June 02, 2009 3:06 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Sound Cards for locking to GPSDO 10
MHz
Hi Rex,
Here is a plot of my sound card. Maybe I'm just lucky with this particular
sound card/computer, but the drift was only about 250 micro Hertz over a
four hour period. Also for critical measurements I try to run at 200 Hz
center frequency rather than 1000 Hz. Cuts the error by five. Maybe
Hi all
Does anyone have any experience of locking a USB external soundcard to a
GPSDO 10 MHz reference.
I am interested in advice on any good quality soundcards that can be readily
locked to either 10 MHz or if necessary to some other frequency that we can
derive from a GPSDO source. I have
Soundcards for USB are poor at best.
I have a set of PCI cards that were previously made by EMU and they accept
external reference input. They no longer make the model I have but perhaps
they have another PCI card with an external ref input.
I am interested in your modulation technique
...@bigpond.net.au
To: 'Discussion of precise time and frequency measurement'
time-nuts@febo.com
Sent: Monday, June 01, 2009 10:59 PM
Subject: [time-nuts] Sound Cards for locking to GPSDO 10 MHz references
Hi all
Does anyone have any experience of locking a USB external soundcard to a
GPSDO 10 MHz
Hi Jeff
Thanks for your advice which I will follow up - the reason for going for a
USB sound card is that the system must be operated portable with a Laptop -
but perhaps there is a way to use a PCI sound card on a Laptop.
While we use WSJT at present we have a new Mode under development for the
rmon...@bigpond.net.au said:
For info the purpose of this request is that we are looking at using
very narrow bandwidth modes at less than 1 mHz for light wave
communcation. To date using LEDs and cloud reflection we have worked
over 200 km with WSJT but we should be able to do 20 dB better
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Jeffrey Pawlan
Sent: Monday, June 01, 2009 3:08 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sound Cards for locking to GPSDO 10 MHz
references
-Original Message-
From: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] On Behalf Of Rex Moncur
Sent: Monday, June 01, 2009 3:00 PM
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] Sound Cards for locking to GPSDO 10 MHz
references
I use a Lynx One sound card, it has analog and digital I/O and MIDI I/O
and clock I/O. Their manuals are available on line at
www.lynxstudio.com. These are profession 24 bit cards, the analog I/O
uses balanced interfaces. They handle AES/EBU and SP DIF digital audio
formats.
The sound
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