Re: [time-nuts] Timestamps in audio files?

[Chris Caudle]

On Mon, December 21, 2015 5:19 am, Tim Shoppa wrote:
> Are there any standard consumer-type audio file formats, that support
> absolute time time/datestamps?

Broadcast WAV file (BWF) is probably the closest.  I'm not sure what
different timecode formats are possible, but this description of how Avid
and Final Cut import time code from BWF files probably indicates what is
commonly used.  I think the usual timecode roles over every 24 hours, I'm
not sure there is a standard way to attach calendar date.  Could be a way
that just isn't decribed here:

BWF Time Code
The recorded files generated by Sound Devices 7-Series recorders and the
552 mixer contain extensive metadata describing their contents. This
metadata is stored in the BeXT and iXML chunks within the Broadcast Wave
format. To represent time code the primary metadata parameters include:

Start TC:  stored in both the bEXT and iXML chunks as a ‘Samples Since
Midnight’ value.
TC frame rate:  This is the frames per second rate. It is also used to
convert the HH:MM:SS:FF time code value to a ‘Samples Since Midnight’
value and visa versa. It is stored in the bEXT chunk as the ‘SPEED’
parameter and in iXML as the ‘TIMECODE_RATE’ parameter.
Sampling Rate:  This is stored in the ‘fmt’ (format) and iXML chunks.
This tells the playback device at what speed to playback the file,
typically 48 kHz in sound-for-picture applications.

-- 
Chris Caudle




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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Anders Wallin]

> > AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
> > input-referred voltage noise PSD (if I calculated correctly..)
>
> With +10dBm input the corresponding SSB PN floor should be  around
> -163dBc/Hz.
>

HI,
How is that calculated? I only get this far:
9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz

what then? split half-and-half into AM and PN, and how to relate that to
the carrier power +10dBm?

thanks,
Anders
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Re: [time-nuts] Timestamps in audio files?

[Tim Shoppa]

Analogies to broadcast timing are interesting, but that seems like a
non-starter today due to multiple cascaded codec latencies.

The video formats I know that use timestamps for historical reconstruction,
just recorded a human-readable timestamp onto the video itself at original
recording time.

Jim, I agree that playing games with the timestamp cause problems with many
players that expect the start to be "00:00:00".

Certainly embedding time info into the transport layer is a possibility.
I'm more interested in the "file" layer today.

I remember to the last time I had to extensively work with analog
recordings with IRIG-type timestamps. The playback console had a LED
playback-clock readout and it was very impressive because with
variable-speed analog playback the LED readout's IRIG decoder would
maintain lock to the timecode. (It must've been one of the
amplitude-modulated IRIG codes now that I think about it, because it would
show hundredths of a second - IRIG-B? - and sometimes we would record it on
a polaroid with a scope and count off fractions of 0.01s. Or maybe it was
0.001s.)

Tim N3QE


On Mon, Dec 21, 2015 at 12:40 PM, Bob Camp  wrote:

> Hi
>
> I sort of suspect that if there *was* a system “broadcasting” time over
> the internet
> (other than NTP) we all would be fooling around locking up oscillators to
> it …
>
> Yes, streaming and time stamping are not the same thing. These days
> though, the
> two probably get crossed between a lot.
>
> Bob
>
> > On Dec 21, 2015, at 10:22 AM, Jim Lux  wrote:
> >
> > On 12/21/15 3:19 AM, Tim Shoppa wrote:
> >> As an adjunct to the thread about timestamped samples of LORAN
> >> transmissions...
> >>
> >> Are there any standard consumer-type audio file formats, that support
> >> absolute time time/datestamps? Would not have to be done continuously,
> but
> >> something like a time and date stamp inserted nearest each sample on a
> >> second boundary.
> >>
> >> I have worked with some analog tape audio formats in the past where
> >> IRIG-type timestamps were written on a separate channel or on a
> subcarrier.
> >>
> >> I know of many proprietary digital recording applications that make
> WAV's
> >> or MP3's or proprietary codec formats, where the filename includes a
> >> timestamp. Much more interested in standard formats where the timestamp
> is
> >> embedded in the file itself.
> >>
> >
> > For RF recordings, VITA49 has a standard for timestamps in the packet
> headers (4 flavors of epoch, multiple flavors of time format and precision)
> >
> > Video file formats seem to draw from older time code things like SMPTE
> and are "relative" (so you're always fooling around trying to figure out
> the offsets).  I spent a few days earlier this year trying to put absolute
> time subtitles on video files using all manner of tools, and it was
> frustrating (ffmpeg, vlc, etc.. all were to no avail).  Trying to put UTC
> time into embedded timecode was also pretty unproductive (most tools don't
> like to see the first frame occurring at a time very different from
> 00:00:00:00)
> >
> >
> > In fact, in the music file world (e.g. MIDI) you see references to
> absolute and relative time, and there, they are really talking about time
> measured in seconds vs time measured in beats; e.g. whether the duration of
> something  is 1 second, or 2 quarter notes, which might be the same if the
> tempo is 120bpm.
> >
> >
> > You might look for solutions for people trying to synchronize multiple
> multimedia streams delivered over the internet (e.g. slides and
> accompanying narration or music) because they actually have a need for
> "show this slide at time HH:MM:SS and play this sound at HH:MM:SS" kind of
> synchronization.
> >
> > I suspect, though, that this kind of info gets encapsulated in the
> transport layer, rather than the underlying files holding the info.
> >
> >
> >
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Re: [time-nuts] SMD TADD-1 distribution amplifier

[Charles Steinmetz]

Anders wrote:


How is that calculated? I only get this far:
9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
what then?


As I said on Dec. 18 in response to the original post, the in-band 
(10MHz) noise is NOT the main problem with respect to AM and PM 
noise.  The main problem is the BASEBAND noise (near DC, say, 
0.1Hz--10Hz).  And the AD8055, as well as the MAX477 originally used 
in the TADD-1, are absolutely horrible in this regard.  Both of them 
have noise densities > 1,000nV/sqrtHz at 10Hz (and even worse below 10Hz).


See my earlier post for a brief explanation of why this is so, and 
how baseband noise is converted to AM and PM noise in the RF signal 
band.  There are also more in-depth explanations in the 
archives.  One search term you can use is "PM conversion."


For low AM and PM noise, you want an opamp with a noise density of 
10nV/sqrtHz, or lower, *at 10 Hz*.  The ADA4899, LME49713, and AD8010 
are three possible choices (these days, there are many others, as well).


Best regards,

Charles


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Re: [time-nuts] 5370B stop trigger not working

[Christopher E. Brown]

You might want to re-scope the start and stop channel outputs where they cross 
A4 and
verify against the front panel labels.

The signal line crossing A4 that lines up with frontpanel start is start and 
the one that
lines up with stop is stop.


I mention this because the A3 board is a carry over from another unit and the 
start/stop
labeling on the board itself is reversed from the 5370B front panel labels and 
the parts
list follows the board labeling.  So, if you read front panel and lookup P/N in 
list you
get the wrong one.


The safe thing is to follow back from the output crossing A4 that is failing and
physically pull the hybrid and read the P/N on the mounting frame.  It should 
be a metal
can in a screw together frame, the part is socketed.


Once the A3 is out, do not remove the screws in frame, they just clamp the 
frame to part.
 Whole thing is held in by the collar on the pot shaft.


For a 5370B

5088-7061 (start channel hybrid)
5088-7062 (stop channel hybrid)

the manual lists it reversed, and they are actually different parts (not just 
diff
mounting frames) with crossed up triggers.


7061 (actual start manual lists as stop) is the one that usually fails and is 
almost
impossible to find.  Took me several years (and the help of another nut with a 
parts unit)
to get a working one.  7062 is much easier to find.


On 12/13/2015 11:26 AM, Jim Palfreyman wrote:
> Oops yes! I looked up the wrong item. I meant A3U1 which is 5088-7061
> 
> Jim
> 
> 
> On Sunday, 13 December 2015, Cok  wrote:
> 
>> According to the partlist A4U1 and A4U2 seems to be TL072CP opamps.
>>
>>>
>>> jim77...@gmail.com said:
>>>
 I have gone through the troubleshooting process from the manual and it
 seems
 to point to A4U2 (Schmidt trigger) being faulty.

>>> I'd put a scope on it to check.
>>>
>>> Before I dive into this, does anyone have any advice? Most important being
 the Schmidt trigger - where do I get one?

>>> You need more info - the manufacturer's part number or something like
>>> that.
>>>
>>>
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Re: [time-nuts] Timestamps in audio files?

[Hal Murray]

tsho...@gmail.com said:
> I know of many proprietary digital recording applications that make WAV's or
> MP3's or proprietary codec formats, where the filename includes a timestamp.
> Much more interested in standard formats where the timestamp is embedded in
> the file itself. 

What sort of accuracy to you want?  Is nearest second good enough or do you 
want time-nut level accuracy?

One thing to keep in mind is that the recording clock may not be accurate, so 
if all you know is the start time, your error bars grow as you move down the 
file.

Recording IRIG on another channel is the best suggestion I've seen.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Timestamps in audio files?

[Bob Camp]

Hi

I sort of suspect that if there *was* a system “broadcasting” time over the 
internet
(other than NTP) we all would be fooling around locking up oscillators to it …

Yes, streaming and time stamping are not the same thing. These days though, the
two probably get crossed between a lot. 

Bob

> On Dec 21, 2015, at 10:22 AM, Jim Lux  wrote:
> 
> On 12/21/15 3:19 AM, Tim Shoppa wrote:
>> As an adjunct to the thread about timestamped samples of LORAN
>> transmissions...
>> 
>> Are there any standard consumer-type audio file formats, that support
>> absolute time time/datestamps? Would not have to be done continuously, but
>> something like a time and date stamp inserted nearest each sample on a
>> second boundary.
>> 
>> I have worked with some analog tape audio formats in the past where
>> IRIG-type timestamps were written on a separate channel or on a subcarrier.
>> 
>> I know of many proprietary digital recording applications that make WAV's
>> or MP3's or proprietary codec formats, where the filename includes a
>> timestamp. Much more interested in standard formats where the timestamp is
>> embedded in the file itself.
>> 
> 
> For RF recordings, VITA49 has a standard for timestamps in the packet headers 
> (4 flavors of epoch, multiple flavors of time format and precision)
> 
> Video file formats seem to draw from older time code things like SMPTE and 
> are "relative" (so you're always fooling around trying to figure out the 
> offsets).  I spent a few days earlier this year trying to put absolute time 
> subtitles on video files using all manner of tools, and it was frustrating 
> (ffmpeg, vlc, etc.. all were to no avail).  Trying to put UTC time into 
> embedded timecode was also pretty unproductive (most tools don't like to see 
> the first frame occurring at a time very different from 00:00:00:00)
> 
> 
> In fact, in the music file world (e.g. MIDI) you see references to absolute 
> and relative time, and there, they are really talking about time measured in 
> seconds vs time measured in beats; e.g. whether the duration of something  is 
> 1 second, or 2 quarter notes, which might be the same if the tempo is 120bpm.
> 
> 
> You might look for solutions for people trying to synchronize multiple 
> multimedia streams delivered over the internet (e.g. slides and accompanying 
> narration or music) because they actually have a need for "show this slide at 
> time HH:MM:SS and play this sound at HH:MM:SS" kind of synchronization.
> 
> I suspect, though, that this kind of info gets encapsulated in the transport 
> layer, rather than the underlying files holding the info.
> 
> 
> 
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Re: [time-nuts] Anybody who can record last Loran-C transmissions ?

[Poul-Henning Kamp]

In message <20151220235152.gc23...@cs.utwente.nl>, Pieter-Tjerk de Boer writes:

>I'm the developer of that WebSDR, and I was already planning to use it to
>make some raw signal recordings on New Year's eve.

Thankyou!

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier

[Bruce Griffiths]

Such blanket statements aren't a particularly useful guide unless calibrated by 
measurements. For example the OPA653 has a measured PN floor of around 
-163dBc/Hz for a +13dBm input and the measured PN @1Hz offset is -150dBc/Hz 
(comparable with the NIST isolation amps).However the voltage noise is 
(estimated) to be 300nV/rtHz @1Hz and about 8nVrtHz @ 10kHz. Whilst the 
measured PN floor agrees closely with the measured value. The input voltage 
noise @1Hz can't be used directly to estimate the PN noise at 1Hz offset.  

Bruce 

On Tuesday, 22 December 2015 12:02 PM, Charles Steinmetz 
 wrote:
 

 Anders wrote:

>How is that calculated? I only get this far:
>9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
>what then?

As I said on Dec. 18 in response to the original post, the in-band 
(10MHz) noise is NOT the main problem with respect to AM and PM 
noise.  The main problem is the BASEBAND noise (near DC, say, 
0.1Hz--10Hz).  And the AD8055, as well as the MAX477 originally used 
in the TADD-1, are absolutely horrible in this regard.  Both of them 
have noise densities > 1,000nV/sqrtHz at 10Hz (and even worse below 10Hz).

See my earlier post for a brief explanation of why this is so, and 
how baseband noise is converted to AM and PM noise in the RF signal 
band.  There are also more in-depth explanations in the 
archives.  One search term you can use is "PM conversion."

For low AM and PM noise, you want an opamp with a noise density of 
10nV/sqrtHz, or lower, *at 10 Hz*.  The ADA4899, LME49713, and AD8010 
are three possible choices (these days, there are many others, as well).

Best regards,

Charles


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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

To go through the whole deal a step at a time *assuming* that broadband noise 
is the only issue:

-147 dbm noise per Hz
+10 dbm signal

=> -157 dbc / Hz

half to AM, half to PM

=> -160 dbc / Hz

ssb is already taken care of (noise on both sides if it’s broadband)

=> -160 dbc / Hz 

Now, assuming you have a modulation on the edge due to low frequency noise:

-147 dbm noise per Hz
+10 dbm signal 
+0 conversion gain (might be less, rarely is more)

=> -157 dbc / Hz
 
It all may go to PM so

=> -157 dbc / Hz

It’s DSB (sidebands are coherent) modulation so 

=> -151 dbc / Hz

You could easily say that all of the stuff after the conversion gain number is 
just messing around. 
That would indeed be correct. All that has been done is to calculate a 
conversion gain for low 
frequency noise to PM as read by a phase noise test set. The main point is to 
illustrate that you 
may be *more* sensitive to low frequency noise than you might think. 

=

Biased CMOS gates are looking better and better … -175 dbc / Hz floor with a 7 
dbm input …. :)

Bob




> On Dec 21, 2015, at 3:05 PM, Anders Wallin  
> wrote:
> 
>>> AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
>>> input-referred voltage noise PSD (if I calculated correctly..)
>> 
>> With +10dBm input the corresponding SSB PN floor should be  around
>> -163dBc/Hz.
>> 
> 
> HI,
> How is that calculated? I only get this far:
> 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
> 
> what then? split half-and-half into AM and PN, and how to relate that to
> the carrier power +10dBm?
> 
> thanks,
> Anders
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[time-nuts] PPS phase between two GPS units.

[dan]

Hi All,
 
So I've been playing with some timing hardware here, and have noticed 
something rather curious. I have two otherwise identical Lea-6T GPS 
modules, configured exactly the same. These units are tied to the same 
antenna, with a splitter with the same length cables running to each 
unit. They were given the same survey coordinates. Initially there was 
not any appreciable difference between the PPS outputs. The outputs 
were on average within about one nS of each other. However after a day 
or two they started to display a difference of about 21nS between the 
PPS outputs. This is also evident in the GPSDO output, as the phase of 
the 10Mhz is also skewed by 21nS or so. 

 
A few days ago I started a 48 hour survey. The came up virtually 
identical coordinates at the end of that survey. After the survey the 
phase is still 21nS different. 

 
At this point, my only thought is the GPS splitter. It's DC coupled to 
one unit, and AC coupled to the other. It is possible there are some 
delays on one output vs. the other due to the blocking caps and bypass 
inductor in the splitter. I've tried swapping the GPSDO units on the 
splitter, so we'll see what happens there. 
 
Can anyone offer any insight as to why the two units may have a 
different PPS output timing? It's not really a problem, more of a 
curiosity and mildly academic exercise. 
 

Thanks,
Dan
 
 
 
 
 
 

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Re: [time-nuts] PPS phase between two GPS units.

[paul swed]

I think you are doing the right test to see if the splitter delay is the
issue 21 ns is mighty small and a real possibility.
Regards
Paul
WB8TSL

On Mon, Dec 21, 2015 at 8:24 PM,  wrote:

> Hi All,
>
> So I've been playing with some timing hardware here, and have noticed
> something rather curious. I have two otherwise identical Lea-6T GPS
> modules, configured exactly the same. These units are tied to the same
> antenna, with a splitter with the same length cables running to each unit.
> They were given the same survey coordinates. Initially there was not any
> appreciable difference between the PPS outputs. The outputs were on average
> within about one nS of each other. However after a day or two they started
> to display a difference of about 21nS between the PPS outputs. This is also
> evident in the GPSDO output, as the phase of the 10Mhz is also skewed by
> 21nS or so.
>
> A few days ago I started a 48 hour survey. The came up virtually identical
> coordinates at the end of that survey. After the survey the phase is still
> 21nS different.
>
> At this point, my only thought is the GPS splitter. It's DC coupled to one
> unit, and AC coupled to the other. It is possible there are some delays on
> one output vs. the other due to the blocking caps and bypass inductor in
> the splitter. I've tried swapping the GPSDO units on the splitter, so we'll
> see what happens there.
> Can anyone offer any insight as to why the two units may have a different
> PPS output timing? It's not really a problem, more of a curiosity and
> mildly academic exercise.
> Thanks,
> Dan
>
>
>
>
>
>
>
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Do those modern CMOS gates use deuterated wafers?I've not found any 
measurements of the PN of modern CMOS gates.The measurements of devices like 
the venerable 74AC04 indicate a PN floor around 10dBc/Hz worse than that.
Bruce
 

On Tuesday, 22 December 2015 3:00 PM, Bob Camp  wrote:
 

 Hi

To go through the whole deal a step at a time *assuming* that broadband noise 
is the only issue:

-147 dbm noise per Hz
+10 dbm signal

=> -157 dbc / Hz

half to AM, half to PM

=> -160 dbc / Hz

ssb is already taken care of (noise on both sides if it’s broadband)

=> -160 dbc / Hz 

Now, assuming you have a modulation on the edge due to low frequency noise:

-147 dbm noise per Hz
+10 dbm signal 
+0 conversion gain (might be less, rarely is more)

=> -157 dbc / Hz
 
It all may go to PM so

=> -157 dbc / Hz

It’s DSB (sidebands are coherent) modulation so 

=> -151 dbc / Hz

You could easily say that all of the stuff after the conversion gain number is 
just messing around. 
That would indeed be correct. All that has been done is to calculate a 
conversion gain for low 
frequency noise to PM as read by a phase noise test set. The main point is to 
illustrate that you 
may be *more* sensitive to low frequency noise than you might think. 

=

Biased CMOS gates are looking better and better … -175 dbc / Hz floor with a 7 
dbm input …. :)

Bob




> On Dec 21, 2015, at 3:05 PM, Anders Wallin  
> wrote:
> 
>>> AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
>>> input-referred voltage noise PSD (if I calculated correctly..)
>> 
>> With +10dBm input the corresponding SSB PN floor should be  around
>> -163dBc/Hz.
>> 
> 
> HI,
> How is that calculated? I only get this far:
> 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
> 
> what then? split half-and-half into AM and PN, and how to relate that to
> the carrier power +10dBm?
> 
> thanks,
> Anders
> ___
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[time-nuts] HP5065A battery pack

[timeok]

I remember the discussion on the battery pack of the HP5065A option 002.
I have right now the opportunity to have an original  pack for service and I 
have taken some picture of it.

see: 
http://www.timeok.it/wp/wp-content/uploads/2015/08/HP5065A-battey-pack-v1.0.pdf

Luciano
www.timeok.it
Message sent via Atmail Open - http://atmail.org/
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[time-nuts] Timestamps in audio files?

[Tim Shoppa]

As an adjunct to the thread about timestamped samples of LORAN
transmissions...

Are there any standard consumer-type audio file formats, that support
absolute time time/datestamps? Would not have to be done continuously, but
something like a time and date stamp inserted nearest each sample on a
second boundary.

I have worked with some analog tape audio formats in the past where
IRIG-type timestamps were written on a separate channel or on a subcarrier.

I know of many proprietary digital recording applications that make WAV's
or MP3's or proprietary codec formats, where the filename includes a
timestamp. Much more interested in standard formats where the timestamp is
embedded in the file itself.

Tim N3QE
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Re: [time-nuts] Timestamps in audio files?

[Jim Lux]

On 12/21/15 3:19 AM, Tim Shoppa wrote:

As an adjunct to the thread about timestamped samples of LORAN
transmissions...

Are there any standard consumer-type audio file formats, that support
absolute time time/datestamps? Would not have to be done continuously, but
something like a time and date stamp inserted nearest each sample on a
second boundary.

I have worked with some analog tape audio formats in the past where
IRIG-type timestamps were written on a separate channel or on a subcarrier.

I know of many proprietary digital recording applications that make WAV's
or MP3's or proprietary codec formats, where the filename includes a
timestamp. Much more interested in standard formats where the timestamp is
embedded in the file itself.



For RF recordings, VITA49 has a standard for timestamps in the packet 
headers (4 flavors of epoch, multiple flavors of time format and precision)


Video file formats seem to draw from older time code things like SMPTE 
and are "relative" (so you're always fooling around trying to figure out 
the offsets).  I spent a few days earlier this year trying to put 
absolute time subtitles on video files using all manner of tools, and it 
was frustrating (ffmpeg, vlc, etc.. all were to no avail).  Trying to 
put UTC time into embedded timecode was also pretty unproductive (most 
tools don't like to see the first frame occurring at a time very 
different from 00:00:00:00)



In fact, in the music file world (e.g. MIDI) you see references to 
absolute and relative time, and there, they are really talking about 
time measured in seconds vs time measured in beats; e.g. whether the 
duration of something  is 1 second, or 2 quarter notes, which might be 
the same if the tempo is 120bpm.



You might look for solutions for people trying to synchronize multiple 
multimedia streams delivered over the internet (e.g. slides and 
accompanying narration or music) because they actually have a need for 
"show this slide at time HH:MM:SS and play this sound at HH:MM:SS" kind 
of synchronization.


I suspect, though, that this kind of info gets encapsulated in the 
transport layer, rather than the underlying files holding the info.




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