Re: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic Clock (DSAC)

[Bill Byrom]

After the successful Falcon Heavy launch earlier this week, it appears that the 
Deep Space Atomic Clock (DSAC) is now scheduled to go up in June 2018 on a 
Falcon Heavy carrying the US Air Force STP-2 test payloads.
https://www.nasa.gov/feature/goddard/2018/nasa-tests-atomic-clock-for-deep-space-navigation

For a fun video about this project suitable for non-time-nuts, see:
https://www.nasa.gov/mission_pages/tdm/clock/sammy-the-second.html

--
Bill Byrom N5BB

On Tue, Mar 21, 2017, at 11:36 PM, Bill Byrom wrote:
> NASA's Deep Space Atomic Clock test mission is moving toward a late-2017
> launch (don't all projects slip?). The DSAC was just integrated with the
> spacecraft. The clock uses a ~40.5 GHz hyperfine transition of mercury
> ions. This steers an ovenized crystal USO (Ultra Stable Oscillator) from
> FEI with 1-100 sec stability <2e-13 and drift <1e-10/day. A GPS receiver
> is also on board:
> https://www.jpl.nasa.gov/news/news.php?feature=6784
> 
> NASA information about the DSAC applications at:
> https://www.nasa.gov/mission_pages/tdm/clock/index.html
> 
> Expected DSAC performance (2014 paper). This paper claims an estimated
> Allan Deviation of <1e-14 (perhaps 3e-15) at a one day interval when in
> space:
> https://www.researchgate.net/publication/260036335_Expected_Performance_of_the_Deep_Space_Atomic_Clock_Mission
> 
> 
> Here are the latest two papers I can find (from Feb 2016):
> 
> ** Deep Space Atomic Clock Technology Demonstration Mission Onboard
> Navigation Analog Experiment:
> https://www.researchgate.net/publication/293648952_Deep_Space_Atomic_Clock_Technology_Demonstration_Mission_Onboard_Navigation_Analog_Experiment
> 
> ** Preliminary Investigation of Onboard Orbit Determination using Deep
> Space Atomic Clock Based Radio Tracking:
> https://www.researchgate.net/publication/293648187_Preliminary_Investigation_of_Onboard_Orbit_Determination_using_Deep_Space_Atomic_Clock_Based_Radio_Tracking
> 
> --
> Bill Byrom N5BB
> 
> - Original message -
> From: Gregory Beat 
> To: time-nuts@febo.com
> Subject: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic
> Clock (DSAC)
> Date: Tue, 12 Jan 2016 17:31:26 -0600
> 
> Upcoming Event: Deep Space Atomic Clock
> Jan. 14, 2016, at 7 p.m. PT (10 p.m. ET, 0300 UTC)
> You can watch this event via USTREAM:  http://www.ustream.tv/NASAJPL2
> 
> Speakers: 
> Todd Ely, DSAC Principal Investigator, JPL
> Allen H. Farrington, DSAC Project Manager, JPL
> http://www.nasa.gov/mission_pages/tdm/clock/clock_overview.html#.VpWMgK9OKK0
> Atomic clocks are an integral, yet almost invisible component of modern
> life. 
> For space exploration, they have been the foundational frequency
> standard for NASA's Deep Space Network. NASA's Deep Space Atomic Clock
> (DSAC) Technology Demonstration Mission, led by the Jet Propulsion
> Laboratory, has been maturing the latest Atomic Clock technologies into
> a smaller package, suitable for installation on a variety of deep space
> probes to enhance navigation precision and gravity science across the
> solar system.
> 
> DSAC is scheduled for launch in mid-2016.  
> Satellite being built by Surrey Satellite Technologies USA, Englewood,
> CO
> 
> 
> Sent from iPad Air
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[time-nuts] Looking for Datum TymServe 2000 (TS2000) manual

[Skip Withrow]

Hello Time-Nuts,
After a very long journey trying to figure out the correct cable
configuration between the AcuTime GPS antenna (receiver) and a Datum
TS2000 I now have it working.  Now I am in need of a manual so I can
talk over the serial port.  The protocol is apparently not the same as
the TS2100.

Any help would be appreciated.

I'm more than happy to share the cable schematic if anyone needs it.
It would be the same for Bancomm bc627 and 635/7 (?) as well as the
TS2000.  If you have any of these units you could probably use many
different Trimble receivers (Resolution-T for instance) with RS-422
converter (though I have not tried it - yet).

Thanks in advance for any help.

Skip Withrow
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Re: [time-nuts] Vanguard TCXO

[jimlux]

On 2/8/18 11:49 AM, Mark Goldberg wrote:

On Thu, Feb 8, 2018 at 10:51 AM, jimlux  wrote:


On 2/8/18 5:34 AM, Mark Goldberg wrote:


What is the phase noise like on the cheap TCXO?Vectron




VT-702 (the first one in the list online)
-99 at 10Hz
-123 at 100Hz
-143 at 1kHz

going to Mouser and looking for the cheapest 10MHz TCXO
FOX924 (about $2) - no data
SiT5000 (about ) - -140 dBc@1kHz, -150 dBcfrom 10k to 100k, -160 @ 1M (no
price)
ECS -TXO-3225-100-TR ($2.71 each) - -135dBc @ 1 kHz
ASTX-H11 ($3.16) -130dBc @ 1 kHz, -158dBc @100k

FOX922CE at 16.369 MHz, -145 @ 10kHz




Can you provide a link to the "list online"?


I just went to digikey and searched for TCXO and 10 MHz




I am always wary when no or few specifications are provided. If you look at
manufacturer;s like Vectron, they provide lots of data, phase noise at many
frequencies, aging, etc.



it's what you pay for - if the spec says -135 at 10kHz, and that's all, 
then that's what they test. - that's cheaper.


A $100 oscillator will tend to have a lot more data than a $2 one 

At some point, you just BUY a batch of oscillators and test them yourself.

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Re: [time-nuts] Receiving the MSF time signal on cheap radio modules

[jks]

> Hal Murray wrote:

> If the two signals are not encoded identically, there should be an 
> interesting signal when one of the transmitters is off and the other is on.  
> Has anybody looked for that sort of pattern?

> Is there a map of the dead spots?  Any time-nuts live in/near one?

Yes. Here is a screenshot of roughly equal strength JJY and WWVB as received in 
New Zealand around 10 PM local time on a KiwiSDR.

Due to the timing reversal of the pulses from each station this results in 
solid carrier during the data bit times (no matter the bit combination: 00, 01, 
10, 11) as the signals are added. The marker pulses every 10 seconds give a 0.6 
sec gap when both stations are at reduced-carrier. And the double marker at the 
minute boundary gives a 1.6 sec gap with a 0.4 sec pulse in the middle. I 
thought this was sort of amusing.

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Re: [time-nuts] Vanguard TCXO

[Mark Goldberg]

On Thu, Feb 8, 2018 at 10:51 AM, jimlux  wrote:

> On 2/8/18 5:34 AM, Mark Goldberg wrote:
>
>> What is the phase noise like on the cheap TCXO?Vectron
>>
>
>
> VT-702 (the first one in the list online)
> -99 at 10Hz
> -123 at 100Hz
> -143 at 1kHz
>
> going to Mouser and looking for the cheapest 10MHz TCXO
> FOX924 (about $2) - no data
> SiT5000 (about ) - -140 dBc@1kHz, -150 dBcfrom 10k to 100k, -160 @ 1M (no
> price)
> ECS -TXO-3225-100-TR ($2.71 each) - -135dBc @ 1 kHz
> ASTX-H11 ($3.16) -130dBc @ 1 kHz, -158dBc @100k
>
> FOX922CE at 16.369 MHz, -145 @ 10kHz
>
>
>
Can you provide a link to the "list online"? I went to eBay and searched
for "Vanguard TCXO" and got a list of them with various frequencies. They
all specify -125 dBc/Hz at 1 khz, which is concerning of itself, as phase
noise generally is higher with higher frequency. They are golden however,
so there's that!

Vectron and others make decent TCXOs, better than -135 dBc/Hz at 1 kHz,
which is what I have measured. I believe none of them are what the original
poster is talking about. For a comparison, a Wenzel OCXO I am using for a
reference is in the range of -155 dBc/Hz at 1 kHz.

I am always wary when no or few specifications are provided. If you look at
manufacturer;s like Vectron, they provide lots of data, phase noise at many
frequencies, aging, etc.

73,

Mark
W7MLG
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[time-nuts] Fast 30ps risetime pulse generator with SMA/2.92mm output

[Leo Bodnar]

I have promised a few people here to let them know when the microwave / SMA 
connector version of my fast risetime pulser is available.
It is available now: 
http://www.leobodnar.com/shop/index.php?main_page=index=124

For those not familiar with what it does - this is a pulse train generator with 
extremely fast risetime of 30ps (10-90% levels).
Falling edge is even faster at about 25-27ps. Pulse edge spacial length is only 
few mm.
Due to very fast edges its spectral content extends from 10MHz to tens of GHz.

Pulser's main purpose is testing bandwidth of time/frequency lab equipment and 
performing TDR/TDT.

Thanks
Leo
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Re: [time-nuts] Vanguard TCXO

[jimlux]

On 2/8/18 5:34 AM, Mark Goldberg wrote:

What is the phase noise like on the cheap TCXO? Being on frequency is far
from the only characteristic that matters. I did some research on cheap
TCXOs for Kenwood radios and found truly awful phase noise and lots of
spurs above and below the oscillator frequency. I don't know if these
characteristics are important for your unit.

One eBay source says -125 dBc/1kHz. (Should be stated as -125 dBc/Hz @ 1
kHz). That is not very good. I found the cheap TCXOs I tested actually had
worse phase noise at 15 - 20 kHz offset.




Vectron
VT-702 (the first one in the list online)
-99 at 10Hz
-123 at 100Hz
-143 at 1kHz

going to Mouser and looking for the cheapest 10MHz TCXO
FOX924 (about $2) - no data
SiT5000 (about ) - -140 dBc@1kHz, -150 dBcfrom 10k to 100k, -160 @ 1M 
(no price)

ECS -TXO-3225-100-TR ($2.71 each) - -135dBc @ 1 kHz
ASTX-H11 ($3.16) -130dBc @ 1 kHz, -158dBc @100k

FOX922CE at 16.369 MHz, -145 @ 10kHz
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[time-nuts] Looking for WJ YIG Tuned GaAs Osc. (YTO)

[NE8S [G.W. Ko] Doc]

Hello, fellow time-nuts, hope all is well with all of you,

I am looking for a Watkins-Johnson WJ-5008-104 YIG Tuned GaAs Oscillator 8.00 
to 12.40 GHz

or 

a Stoddart-Singer-Ailtech-Carnel Labs NM-67 Microwave Receiver for parts only.

If you can help or send me any leads the contact email is dr...@fcc.ms

Please keep replies, contacts and comments off-line and directed to my email 
provided.

Many thanks!

Doc, NE8S
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Re: [time-nuts] Receiving the MSF time signal on cheap radio modules

[Deirdre O'Byrne]

Challenge accepted.

This graph is probably not too useful, for the simple reason that when the
receiver is spitting out mostly noise, the averages are going to be
massively affected.
[image: Inline images 1]

On 7 February 2018 at 01:03, Hal Murray  wrote:

>
> deirdre@gmail.com said:
> > MSF disciplined oscillator?! I don't trust these receivers to any better
> > than about the 20ms mark, so such a disciplined oscillator would have
> quite
> > a long integration time!
>
> It would be interesting to see if you can find any pattern in your
> histogram
> plots.  Say, time of day.
>
> What happens if you average over 10 or 100 samples?
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] Vanguard TCXO

[Mark Goldberg]

What is the phase noise like on the cheap TCXO? Being on frequency is far
from the only characteristic that matters. I did some research on cheap
TCXOs for Kenwood radios and found truly awful phase noise and lots of
spurs above and below the oscillator frequency. I don't know if these
characteristics are important for your unit.

One eBay source says -125 dBc/1kHz. (Should be stated as -125 dBc/Hz @ 1
kHz). That is not very good. I found the cheap TCXOs I tested actually had
worse phase noise at 15 - 20 kHz offset.

Mark
W7MLG

On Feb 8, 2018 4:24 AM, "Thomas Allgeier"  wrote:

> Hello All,
>
> This is for the medium-precision nuts amongst us. I have invested £14.50
> in one of these Vanguard 0.1ppm TCXO's to pimp my Siglent FG which has a
> footprint for it. It is its internal ref at 25 MHz. The swapping-in was
> simple to do and the FG works fine with it. Since it has a counter mode I
> did a quick check to show whether it was worthwile: I made it count the 10
> MHz from my Proteus GPSDO. The Siglent reads to 1 Hz and straight after
> turn-on it went straight to 10.00 MHz. Over about 1 day I never saw it
> more than +/-1 Hz off, and this involved a deliberate temperature change of
> just over 5 deg C, basically by having the heating in the room off and on.
> For most of the time the display sat solidly at 10.00.
>
> So, to summarise, in a rough sort of way the thing lives up to its 0.1ppm
> spec, at least around the 20C temperature mark. I bought it from a Hong
> Kong seller on Ebay - naturally there is always a chance that other devices
> sold with the same description/label might not perform as well.
>
> I'm quite aware that the generator (DDS) suffers from other sources of
> error, which won't be improved by the clock being better, but at least the
> nominal frequencies it outputs are now going to be very close to the mark
> without the need for an external ref.
>
> Kind regards,
>
> Thomas.
>
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Re: [time-nuts] Does a frequency counter locked to GPS need to "warm up"?

[paul swed]

Exactly what I have run into.
Some systems lock an internal reference to to the incoming system. So that
oven has to come up to temp. Then the trigger and interpolators need to
warm up and stabilize.

So the really right answer is what accuracy are you looking for? Because
what I mention above may simply not matter.
Regards
Paul
WB8TSL

On Thu, Feb 8, 2018 at 9:16 AM, Scott McGrath  wrote:

> Yes,   You have removed the reference from the warmup but the input
> circuits still need time to reach thermal equilibrium for most accurate
> results
>
>
>
> On Feb 8, 2018, at 3:34 AM, Azelio Boriani 
> wrote:
>
> No warmup needed if the counter switches to the external reference. If
> the counter uses the external reference to lock the internal one then
> it is better to wait until the internal one is stable, maybe the
> counter has a standby mode where it appears powered off but the
> internal reference is active (usually an ovenized reference). For the
> best performance (stability of trigger levels, input amplifiers and so
> on) it is better to warmup the whole counter always.
>
> > On Thu, Feb 8, 2018 at 8:33 AM, Chris Wilson 
> wrote:
> >
> >
> >  08/02/2018 07:31
> >
> > Does  a  frequency  counter  connected  to a permanently running
> (Trimble Thunderbolt) GPS
> > disciplined frequency standard need to warm up after switch on before
> readings settle?
> > Just curious, thanks.
> >
> > --
> >   Best Regards,
> >   Chris Wilson.
> > mailto: ch...@chriswilson.tv
> >
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Re: [time-nuts] Does a frequency counter locked to GPS need to "warm up"?

[Magnus Danielson]

Hi,

Well, actually there is two methods:

1) Switch reference clock - a switch or mux changes which clock is being
used.

2) Lock internal reference to external reference - a PLL lock of the
internal reference to the external reference is enabled.

For both, the counter core may need to heat up.

For the first, the internal reference heatup can be ignored completely.

For the second, the internal reference heatup cannot completely be
ignored, it takes time for it to be within lock range and the lock-in
behavior stabilizes. Still relatively quick, but an actual effect.

At the end of the day, it depends on how precise you attempt to measure.

Cheers,
Magnus

On 02/08/2018 03:16 PM, Scott McGrath wrote:
> Yes,   You have removed the reference from the warmup but the input circuits 
> still need time to reach thermal equilibrium for most accurate results
> 
> 
> 
> On Feb 8, 2018, at 3:34 AM, Azelio Boriani  wrote:
> 
> No warmup needed if the counter switches to the external reference. If
> the counter uses the external reference to lock the internal one then
> it is better to wait until the internal one is stable, maybe the
> counter has a standby mode where it appears powered off but the
> internal reference is active (usually an ovenized reference). For the
> best performance (stability of trigger levels, input amplifiers and so
> on) it is better to warmup the whole counter always.
> 
>> On Thu, Feb 8, 2018 at 8:33 AM, Chris Wilson  wrote:
>>
>>
>>  08/02/2018 07:31
>>
>> Does  a  frequency  counter  connected  to a permanently running (Trimble 
>> Thunderbolt) GPS
>> disciplined frequency standard need to warm up after switch on before 
>> readings settle?
>> Just curious, thanks.
>>
>> --
>>   Best Regards,
>>   Chris Wilson.
>> mailto: ch...@chriswilson.tv
>>
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Re: [time-nuts] Does a frequency counter locked to GPS need to "warm up"?

[Scott McGrath]

Yes,   You have removed the reference from the warmup but the input circuits 
still need time to reach thermal equilibrium for most accurate results



On Feb 8, 2018, at 3:34 AM, Azelio Boriani  wrote:

No warmup needed if the counter switches to the external reference. If
the counter uses the external reference to lock the internal one then
it is better to wait until the internal one is stable, maybe the
counter has a standby mode where it appears powered off but the
internal reference is active (usually an ovenized reference). For the
best performance (stability of trigger levels, input amplifiers and so
on) it is better to warmup the whole counter always.

> On Thu, Feb 8, 2018 at 8:33 AM, Chris Wilson  wrote:
> 
> 
>  08/02/2018 07:31
> 
> Does  a  frequency  counter  connected  to a permanently running (Trimble 
> Thunderbolt) GPS
> disciplined frequency standard need to warm up after switch on before 
> readings settle?
> Just curious, thanks.
> 
> --
>   Best Regards,
>   Chris Wilson.
> mailto: ch...@chriswilson.tv
> 
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Re: [time-nuts] Does a frequency counter locked to GPS need to "warm up"?

[Bob kb8tq]

Hi

It depends a *lot* on the frequency counter. An old style “just count the 
number of
edges” device should be good to go pretty fast. One of the “fry an egg on it” 
interpolating 
counters that get into the 20 ps range may well need some time to stabilize. If 
you 
are doing ADEV runs, a couple hours of warmup would be a good idea.

Bob

> On Feb 8, 2018, at 2:33 AM, Chris Wilson  wrote:
> 
> 
> 
>  08/02/2018 07:31
> 
> Does  a  frequency  counter  connected  to a permanently running (Trimble 
> Thunderbolt) GPS
> disciplined frequency standard need to warm up after switch on before 
> readings settle?
> Just curious, thanks.
> 
> -- 
>   Best Regards,
>   Chris Wilson.
> mailto: ch...@chriswilson.tv
> 
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Re: [time-nuts] Anyone have experience with this antenna?

[Thomas Petig]

On Wed, Feb 07, 2018 at 03:07:24PM +, Poul-Henning Kamp wrote:
> 
> In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes:
>
> >Water wise, one might note the large piles of snow sitting on my antennas at 
> >the moment. Yes, I
> >could go knock it off, but somehow it just keeps coming back. Weird how 
> >winter works …. There
> >is no perfect solution.
>
> Somebody at BIPM told me that their antennas were heated and thermostatically
> kept at constant temperature.
This is how you (can) do it. Here a small picture and some info:
https://www.sp.se/en/index/resources/GNSS/Sidor/default.aspx

Thomas, SA6CID
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[time-nuts] Vanguard TCXO

[Thomas Allgeier]

Hello All,

This is for the medium-precision nuts amongst us. I have invested £14.50 
in one of these Vanguard 0.1ppm TCXO's to pimp my Siglent FG which has a 
footprint for it. It is its internal ref at 25 MHz. The swapping-in was 
simple to do and the FG works fine with it. Since it has a counter mode 
I did a quick check to show whether it was worthwile: I made it count 
the 10 MHz from my Proteus GPSDO. The Siglent reads to 1 Hz and straight 
after turn-on it went straight to 10.00 MHz. Over about 1 day I 
never saw it more than +/-1 Hz off, and this involved a deliberate 
temperature change of just over 5 deg C, basically by having the heating 
in the room off and on. For most of the time the display sat solidly at 
10.00.


So, to summarise, in a rough sort of way the thing lives up to its 
0.1ppm spec, at least around the 20C temperature mark. I bought it from 
a Hong Kong seller on Ebay - naturally there is always a chance that 
other devices sold with the same description/label might not perform as 
well.


I'm quite aware that the generator (DDS) suffers from other sources of 
error, which won't be improved by the clock being better, but at least 
the nominal frequencies it outputs are now going to be very close to the 
mark without the need for an external ref.


Kind regards,

Thomas.

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Re: [time-nuts] Does a frequency counter locked to GPS need to "warm up"?

[Magnus Danielson]

Hi,

On 02/08/2018 08:33 AM, Chris Wilson wrote:
> 
> 
>   08/02/2018 07:31
> 
> Does  a  frequency  counter  connected  to a permanently running (Trimble 
> Thunderbolt) GPS
> disciplined frequency standard need to warm up after switch on before 
> readings settle?
> Just curious, thanks.
> 

Well, while the internal reference is not directly steering, if it is
being locked to the external reference, at least some warming up is
needed before it is very stable.

Also, depending on the details of the counters, high resolution
interpolators may need warmup to perform well and for the autocal to
perform meaningfull values.

However, usually it's not very long times and often shaddowed by the
internal referece anyway.

Just to get a rough reading, no. If you want to trust it and trust the
noise, let it warm up for half an hour or so.

Cheers,
Magnus
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Re: [time-nuts] Does a frequency counter locked to GPS need to "warm up"?

[Azelio Boriani]

No warmup needed if the counter switches to the external reference. If
the counter uses the external reference to lock the internal one then
it is better to wait until the internal one is stable, maybe the
counter has a standby mode where it appears powered off but the
internal reference is active (usually an ovenized reference). For the
best performance (stability of trigger levels, input amplifiers and so
on) it is better to warmup the whole counter always.

On Thu, Feb 8, 2018 at 8:33 AM, Chris Wilson  wrote:
>
>
>   08/02/2018 07:31
>
> Does  a  frequency  counter  connected  to a permanently running (Trimble 
> Thunderbolt) GPS
> disciplined frequency standard need to warm up after switch on before 
> readings settle?
> Just curious, thanks.
>
> --
>Best Regards,
>Chris Wilson.
> mailto: ch...@chriswilson.tv
>
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