Re: [time-nuts] Fw: Cell timing error

[lists]

Yeah, the TruePosition website is quite interesting. It seems they do a bit 
more than 911 service. ;-) 

Feel free to change the #3 in the file name to whatever for more shots of the 
interior. 


-Original Message-
From: Dennis Ferguson 
Sender: time-nuts-boun...@febo.com
Date: Sat, 15 Dec 2012 22:58:39 
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Fw:  Cell timing error


On 15 Dec, 2012, at 21:30 , gary  wrote:
> This is a shot of the GPS timing rack in an AT&T shack.
>> http://www.lazygranch.com/images/att/att_3.jpg

Yes, the TruePosition box helps compute handset locations for
E911 and whomever else wants to know where your phone is.  This
isn't a unit you would necessarily see in cell closets in other
countries.

Dennis Ferguson

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Re: [time-nuts] Cell timing error

[Dennis Ferguson]

On 15 Dec, 2012, at 22:38 , Hal Murray  wrote:

> 
>> GSM cell sites in the US have GPS because it is required to support E911
>> positioning.  I'm not sure if it is used for anything other than this, but
>> it doesn't have to be. 
> 
> So it's cheaper to install and maintain GPS rather than make one measurement 
> and tell the setup where it is?

E911 requires the carrier to be able to figure out where the handsets
are.  I think GPS is used as a common timing reference so they can
triangulate to locate the phone using time-of-arrival measurements
of the handset's transmissions made at several cell towers.

GSM/UMTS carriers do it this way, at least.  CDMA2000 carriers instead
rely on the handsets to make the time-of-arrival measurements, both
of signals from cell towers and of GPS signals the handset can hear.

Dennis Ferguson
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Re: [time-nuts] Fw: Cell timing error

[Dennis Ferguson]

On 15 Dec, 2012, at 21:30 , gary  wrote:
> This is a shot of the GPS timing rack in an AT&T shack.
>> http://www.lazygranch.com/images/att/att_3.jpg

Yes, the TruePosition box helps compute handset locations for
E911 and whomever else wants to know where your phone is.  This
isn't a unit you would necessarily see in cell closets in other
countries.

Dennis Ferguson

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Re: [time-nuts] RaspberryPi and RADclock

[Julien Ridoux]

Hi all,

Thanks for pointing this out, I have fixed the plots and the units now read 
"us" for micro-second.

The original intention was to use Latex to generate a beautiful $\mu$ greek 
letter, but urgent work got the best of me. I did apply a quick fix and will 
improve things with our next series of measurements on the raspberry pi.

Cheers,
Julien


On 13/12/2012, at 10:55 PM, Bob Camp  wrote:

> Hi
> 
> Shouldn't mus be mili-micro seconds? :)
> 
> If you go back far enough you will indeed find gear calibrated in mu (mili 
> micro) and uu (micro micro) seconds. I've been doing this for "quite a while" 
> and that was well before my time….
> 
> Bob
> 
> On Dec 12, 2012, at 11:33 PM, Matt Davis  wrote:
> 
>> Hi Magnus,
>> 
>>> From: Magnus Danielson 
>>> Matt,
>>> 
>>> On 12/12/2012 10:23 PM, Matt Davis wrote:
 Hey time-legumes, I figured a few of you all might be interested in some 
 of the
 work that the team and I have been doing.  We recently acquired a couple of
 RaspberryPis, and out of curiosity, we wanted to see how well our RADclock
 software performs on this small platform.  Anyways, our dive into the
 micro-platform world is on our blog:
 
 http://synclab.org/?post=blog/2012/11/radclock-raspberry-stability-nic-noise.html
>>> 
>>> Interesting.
>>> 
>>> What is mus in those graphs? Microseconds? I would expect us in that 
>>> case, milimicroseconds looks wrong.
>> 
>> You are correct, the 'mus' refers to microseconds.
>> 
>> -Matt
>> 
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Re: [time-nuts] Cell timing error

[Hal Murray]

> GSM cell sites in the US have GPS because it is required to support E911
> positioning.  I'm not sure if it is used for anything other than this, but
> it doesn't have to be. 

So it's cheaper to install and maintain GPS rather than make one measurement 
and tell the setup where it is?


-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] Fw: Cell timing error

[gary]

My Starloc was a pull from a wireless shack. We should have DGPSOs up to 
our armpits, but I guess most were crushed.


This is a shot of the GPS timing rack in an AT&T shack.

http://www.lazygranch.com/images/att/att_3.jpg


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[time-nuts] Fw: Cell timing error

[Joseph Orsak]

GSM sites do indeed have GPS antennas. But Dennis is correct; all of them 
use GPS for E911 compliance, the GSM standard wasn't up to that task so 
sites have an outboard box (LMU -  Location Messaging Unit) which provides 
E911 Location independent of the actual cell site base station.
By the way - that's where most of the surplus Thunderbolts came from - a 
particular LMU manufacturer ran up against some patent issues and had to 
take a bunch of product off the market.


That said, yes, some, but a very few, GSM BTS's that I'm familiar with use 
GPS as a radio timing source.


Unless your 3G UMTS smartphone has an AGPS chip built in and turned on when 
you dial 911 the system hands down your call to GSM for the LMU to do it's 
thing. Same for 4G LTE, well at this point in the USA anyway, when you make 
any voice call from an LTE device it drops the call down onto the 3G or GSM 
network. I think Korea has LTE VOIP working maybe?


-Joe

- Original Message - 
From: "Dennis Ferguson" 
To: "Discussion of precise time and frequency measurement" 


Sent: Saturday, December 15, 2012 8:04 PM
Subject: Re: [time-nuts] Cell timing error



GSM cell sites in the US have GPS because it is required to
support E911 positioning.  I'm not sure if it is used for anything
other than this, but it doesn't have to be.

In some other parts of the world it has been considered bad taste
to let the operation of telecommunications infrastructure become
dependent on a facility owned by the US military, so the standards
that are popular there often try to avoid that.

Dennis Ferguson

On 15 Dec, 2012, at 18:59 , li...@lazygranch.com wrote:
I can assure you the GSM shacks have GPS timing in them. I can dig up the 
photos if you want.


-Original Message-
From: "Joseph Orsak" 
Sender: time-nuts-boun...@febo.com
Date: Sat, 15 Dec 2012 18:24:20
To: Discussion of precise time and frequency 
measurement

Reply-To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Cell timing error

AT&T uses UMTS in most areas which is a "self-synchronizing" modulation
scheme. Supposedly one of the selling points is "no dependence on GPS". 
All

the extra sync channels and sync messaging is a capacity hog, not a very
spectrally efficient standard in my opinion.

About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL
sector/carrier before it starts to fall apart. A big step backwards from
good old CDMA2000 (also just my opinion).

But hey, you can surf the web while you talk on the same device.



-Joe W4WN


- Original Message - 
From: "Jim Lux" 

To: "Discussion of precise time and frequency measurement"

Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error



On 12/15/12 2:16 PM, Scott McGrath wrote:

In a prior life we had a CDMA timing receiver for NTP which used VZ for
its source

On Dec 15, 2012, at 12:18 PM, Graham / KE9H 
wrote:


You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.


On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone 
times
very close to 1 min slow.  Virgin/sprint is ok.   I've never seen 
this

before - usually it's a few s slow.




The time *displayed* on the phone might not reflect the time from the
network.

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Re: [time-nuts] Cell timing error

[David]

I thought the networks did that deliberately to frustrate automated
time shifting.

On Sat, 15 Dec 2012 19:04:05 -0500, Joe Leikhim 
wrote:

>I have to wonder how seriously these network designers are with respect 
>to timing.
>
>For example we have Brighthouse cable. The time on the cable box clock 
>is correct to WWV, however the program material is consistently 30 
>seconds or so late meaning the end of the program is cut off. Since my 
>wife tends to record everything on the air, it is not practical to 
>extend the recorder by a minute or a conflict occurs with other recordings.

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Re: [time-nuts] Cell timing error

[Dennis Ferguson]

GSM cell sites in the US have GPS because it is required to
support E911 positioning.  I'm not sure if it is used for anything
other than this, but it doesn't have to be.

In some other parts of the world it has been considered bad taste
to let the operation of telecommunications infrastructure become
dependent on a facility owned by the US military, so the standards
that are popular there often try to avoid that.

Dennis Ferguson

On 15 Dec, 2012, at 18:59 , li...@lazygranch.com wrote:
> I can assure you the GSM shacks have GPS timing in them. I can dig up the 
> photos if you want.
> 
> -Original Message-
> From: "Joseph Orsak" 
> Sender: time-nuts-boun...@febo.com
> Date: Sat, 15 Dec 2012 18:24:20 
> To: Discussion of precise time and frequency measurement
> Reply-To: Discussion of precise time and frequency measurement
>   
> Subject: Re: [time-nuts] Cell timing error
> 
> AT&T uses UMTS in most areas which is a "self-synchronizing" modulation 
> scheme. Supposedly one of the selling points is "no dependence on GPS". All 
> the extra sync channels and sync messaging is a capacity hog, not a very 
> spectrally efficient standard in my opinion.
> 
> About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL 
> sector/carrier before it starts to fall apart. A big step backwards from 
> good old CDMA2000 (also just my opinion).
> 
> But hey, you can surf the web while you talk on the same device.
> 
> 
> 
> -Joe W4WN
> 
> 
> - Original Message - 
> From: "Jim Lux" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Sent: Saturday, December 15, 2012 5:43 PM
> Subject: Re: [time-nuts] Cell timing error
> 
> 
>> On 12/15/12 2:16 PM, Scott McGrath wrote:
>>> In a prior life we had a CDMA timing receiver for NTP which used VZ for 
>>> its source
>>> 
>>> On Dec 15, 2012, at 12:18 PM, Graham / KE9H  
>>> wrote:
>>> 
 You should switch to Verizon.
 They are inherently accurate to milliseconds.
 Sub micro-seconds inside the base stations.
 
 
 On 12/15/2012 12:51 PM, Greg Troxel wrote:
> In central mass, AT&T and tracfone (? carrier) are showing phone times 
> very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
> before - usually it's a few s slow.
> 
>> 
>> 
>> The time *displayed* on the phone might not reflect the time from the 
>> network.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> 
> 
> 
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Re: [time-nuts] Cell timing error

[Magnus Danielson]

On 12/16/2012 12:59 AM, li...@lazygranch.com wrote:

I can assure you the GSM shacks have GPS timing in them. I can dig up the 
photos if you want.


Depens on how the network was built. GSM does not need anything but +/- 
50 ppb timing. The PDH backhaul will provide that usually. The time that 
the mobile get's comes from the controler, which could be slaved using 
NTP... or not. It may not even transfer time, since this is an option 
which many but not all operators have enabled.


Cheers,
Magnus

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[time-nuts] Cell timing error

[Joe Leikhim]

I have to wonder how seriously these network designers are with respect 
to timing.


For example we have Brighthouse cable. The time on the cable box clock 
is correct to WWV, however the program material is consistently 30 
seconds or so late meaning the end of the program is cut off. Since my 
wife tends to record everything on the air, it is not practical to 
extend the recorder by a minute or a conflict occurs with other recordings.



Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM


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Re: [time-nuts] Cell timing error

[lists]

I can assure you the GSM shacks have GPS timing in them. I can dig up the 
photos if you want.

-Original Message-
From: "Joseph Orsak" 
Sender: time-nuts-boun...@febo.com
Date: Sat, 15 Dec 2012 18:24:20 
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Cell timing error

AT&T uses UMTS in most areas which is a "self-synchronizing" modulation 
scheme. Supposedly one of the selling points is "no dependence on GPS". All 
the extra sync channels and sync messaging is a capacity hog, not a very 
spectrally efficient standard in my opinion.

About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL 
sector/carrier before it starts to fall apart. A big step backwards from 
good old CDMA2000 (also just my opinion).

But hey, you can surf the web while you talk on the same device.



-Joe W4WN


- Original Message - 
From: "Jim Lux" 
To: "Discussion of precise time and frequency measurement" 

Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error


> On 12/15/12 2:16 PM, Scott McGrath wrote:
>> In a prior life we had a CDMA timing receiver for NTP which used VZ for 
>> its source
>>
>> On Dec 15, 2012, at 12:18 PM, Graham / KE9H  
>> wrote:
>>
>>> You should switch to Verizon.
>>> They are inherently accurate to milliseconds.
>>> Sub micro-seconds inside the base stations.
>>>
>>>
>>> On 12/15/2012 12:51 PM, Greg Troxel wrote:
 In central mass, AT&T and tracfone (? carrier) are showing phone times 
 very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
 before - usually it's a few s slow.

>
>
> The time *displayed* on the phone might not reflect the time from the 
> network.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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> 



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Re: [time-nuts] 10 MHz output level from DATUM 9390...

[Ziggy]

Burt -

On the scope I see 950mv RMS with 50 ohm termination, 1.5V RMS with 1M. This is 
on a 9390-6000 OCXO with the default timing output configuration, 10MHz on J7. 
Hope this helps.

Paul - K9MR

On Dec 15, 2012, at 4:21 PM, Burt I. Weiner wrote:

Gang,

Does anyone have a DATUM 9390 series GPS receiver that can tell me what the (50 
Ohm) terminated output level of the 10 MHz spigot is.  One of mine started 
spurring and the other one is clean, but seems way to high in output level.

Thanks,

Burt, K6OQK

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 

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Re: [time-nuts] Cell timing error

[Bob Camp]

Hi

There are a *lot* of layers between the base station and the phone it's self 
when it comes to the time that's displayed. There also are a *lot* of 
opportunities  for error as each layer is linked together. Often when you see 
"Verizon" you are actually connected to "Bob's Cell Phone Tower".  Bob may or 
(may not) be very careful about linking all the layers together. 

Best bet, use something like an NTP client, that goes *around* all the network 
"stuff".

Bob

On Dec 15, 2012, at 5:43 PM, Jim Lux  wrote:

> On 12/15/12 2:16 PM, Scott McGrath wrote:
>> In a prior life we had a CDMA timing receiver for NTP which used VZ for its 
>> source
>> 
>> On Dec 15, 2012, at 12:18 PM, Graham / KE9H  wrote:
>> 
>>> You should switch to Verizon.
>>> They are inherently accurate to milliseconds.
>>> Sub micro-seconds inside the base stations.
>>> 
>>> 
>>> On 12/15/2012 12:51 PM, Greg Troxel wrote:
 In central mass, AT&T and tracfone (? carrier) are showing phone times 
 very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
 before - usually it's a few s slow.
 
> 
> 
> The time *displayed* on the phone might not reflect the time from the network.
> 
> ___
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Re: [time-nuts] Cell timing error

[Joseph Orsak]

AT&T uses UMTS in most areas which is a "self-synchronizing" modulation 
scheme. Supposedly one of the selling points is "no dependence on GPS". All 
the extra sync channels and sync messaging is a capacity hog, not a very 
spectrally efficient standard in my opinion.


About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL 
sector/carrier before it starts to fall apart. A big step backwards from 
good old CDMA2000 (also just my opinion).


But hey, you can surf the web while you talk on the same device.



-Joe W4WN


- Original Message - 
From: "Jim Lux" 
To: "Discussion of precise time and frequency measurement" 


Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error



On 12/15/12 2:16 PM, Scott McGrath wrote:
In a prior life we had a CDMA timing receiver for NTP which used VZ for 
its source


On Dec 15, 2012, at 12:18 PM, Graham / KE9H  
wrote:



You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.


On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times 
very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
before - usually it's a few s slow.





The time *displayed* on the phone might not reflect the time from the 
network.


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Re: [time-nuts] Cell timing error

[Jim Lux]

On 12/15/12 2:16 PM, Scott McGrath wrote:

In a prior life we had a CDMA timing receiver for NTP which used VZ for its 
source

On Dec 15, 2012, at 12:18 PM, Graham / KE9H  wrote:


You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.


On 12/15/2012 12:51 PM, Greg Troxel wrote:

In central mass, AT&T and tracfone (? carrier) are showing phone times very 
close to 1 min slow.  Virgin/sprint is ok.   I've never seen this before - usually 
it's a few s slow.




The time *displayed* on the phone might not reflect the time from the 
network.


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Re: [time-nuts] Cell timing error

[Scott McGrath]

In a prior life we had a CDMA timing receiver for NTP which used VZ for its 
source

Sent from my iPhone

On Dec 15, 2012, at 12:18 PM, Graham / KE9H  wrote:

> Greg:
> 
> You should switch to Verizon.
> They are inherently accurate to milliseconds.
> Sub micro-seconds inside the base stations.
> 
> --- Graham / KE9H
> 
> ==
> 
> On 12/15/2012 12:51 PM, Greg Troxel wrote:
>> In central mass, AT&T and tracfone (? carrier) are showing phone times very 
>> close to 1 min slow.  Virgin/sprint is ok.   I've never seen this before - 
>> usually it's a few s slow.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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[time-nuts] 10 MHz output level from DATUM 9390...

[Burt I. Weiner]

Gang,

Does anyone have a DATUM 9390 series GPS receiver that can tell me 
what the (50 Ohm) terminated output level of the 10 MHz spigot 
is.  One of mine started spurring and the other one is clean, but 
seems way to high in output level.


Thanks,

Burt, K6OQK

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 



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Re: [time-nuts] Cell timing error

[Graham / KE9H]

Greg:

You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.

--- Graham / KE9H

==

On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times 
very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this 
before - usually it's a few s slow.


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Re: [time-nuts] RaspberryPi and RADclock

[paul swed]

David thats what I was looking for thanks. At 4 watts that is impressive.
Regards
Paul
WB8TSL

On Sat, Dec 15, 2012 at 2:07 AM, David J Taylor <
david-tay...@blueyonder.co.uk> wrote:

> From: paul swed
>
>
> Thanks.
> I really like the idea that a Rassberry Pi could be a time server. Maybe
> enough to get me going.
> Thanks
> ==**=
>
> Paul,
>
> I wrote up my experiences with the Raspberry Pi as a standard NTP server
> here:
>
>  
> http://www.satsignal.eu/ntp/**Raspberry-Pi-NTP.html
>
> and the performance can be seen here:
>
>  
> http://www.satsignal.eu/ntp/**Raspberry-Pi-NTP.html#current
>  
> http://www.satsignal.eu/mrtg/**performance_ntp-pn.php
>
> Interestingly, the second RPi card is doing better than the first, and it
> does /not/ have gpsd installed, so relying on the LAW/WAN for its source of
> coarse seconds.   But it has a timekeeping GPS and a slightly better
> located antenna as well - both antennas are indoors and some drop-outs show
> as spikes on RasPi-1.  No gpsd appears to mean less CPU load.  Compare:
>
>  
> http://www.satsignal.eu/mrtg/**performance_raspi-1.php
>  
> http://www.satsignal.eu/mrtg/**performance_raspi-2.php
>
> It looks like sub-microsecond might be possible in a
> temperature-controlled environment, as the main drift seems to be at 05:30
> when the heating turns on:
>
>  
> http://www.satsignal.eu/mrtg/**performance_ntp.php?period=**week
>
> Raspberry Pi 2 was only switched to GPS from LAN-only sync a few days ago.
>
> Cheers,
> David
> --
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
>
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[time-nuts] Cell timing error

[Greg Troxel]

In central mass, AT&T and tracfone (? carrier) are showing phone times  
very close to 1 min slow.  Virgin/sprint is ok.   I've never seen this  
before - usually it's a few s slow.


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Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update

[Bob Camp]

Hi

Unless you have a very fancy receiver, the cabling should not matter much. The 
antenna is a bigger issue, but again it depends on just how fancy you are 
getting and how good the antenna is. Right now, I would not worry about either 
one. Use good quality RG-6 quad shield satellite TV coax and it should be fine.

Location of the antenna matters more than either of the above. You want a good 
view of the southern sky. 

Bob

On Dec 15, 2012, at 9:02 AM, Fabio Eboli  wrote:

> Thank you all for the advices.
> I will prepare the setup for a longer logging session,
> using an inverter and a battery for power backup.
> 
> Now I'm starting building of a clock shaper
> and a divider for the 10MHz signal, I will use
> 7AC gates for both the squarer and divider, since I
> have many of them here, no need to buy anything.
> 
> The question is: watching the previous log,
> how much will the results be influenced by
> the GPS antenna and it's cabling ?
> (now I'm using this one: 
> http://www.mirifica.it/store/gps-antenne/347-globaltop-fgpane-sma-5-m.html)
> 
> Thanks,
> Fabio.
> 
> Azelio Boriani  ha scritto:
> 
>> Yes, this is the typical GPS receiver PPS wander. It is usable for a GPSDO
>> as it seems of timing quality (the Motorola M12M is -20nS..+20nS over 10
>> days).
>> See:
>> 
>> http://www.jackson-labs.com/assets/uploads/main/Motorola_M12.pdf
>> 
>> on page 7.
>> 
>> On Thu, Dec 13, 2012 at 2:47 PM, Bob Camp  wrote:
>> 
>>> Hi
>>> 
>>> Ok, those plots look much more "real". Thanks for sharing.
>>> 
>>> Bob
>>> 
>>> -Original Message-
>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>>> Behalf Of Fabio Eboli
>>> Sent: Thursday, December 13, 2012 7:58 AM
>>> To: time-nuts@febo.com
>>> Subject: Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
>>> 
>>> Bob, timenutters
>>> here are the first results, hope
>>> I'm not boring the members with these
>>> posts, for most participants these
>>> are basic things.
>>> Now I'm trying to understand if the
>>> setup is working or I have to modify
>>> some things.
>>> 
>>> The logging is at 47000 samples and going,
>>> the script is working well now, and I dont
>>> have glitches so far.
>>> Raw data, time interval between the pulses:
>>> http://www.flickr.com/photos/14336723@N08/8269800802/
>>> 
>>> Positive thing is that the drift seem consistent
>>> with the previous decimated pulse period data.
>>> 
>>> Data corrected for linear drift and offset, the
>>> actual values are in the graph:
>>> http://www.flickr.com/photos/14336723@N08/8269800868/
>>> 
>>> Here I dont' like very much what I see,
>>> but surely I'm not knowledgeable enough
>>> to judge the data :)
>>> 
>>> Some notes for who didnt read previous posts:
>>> Racal 1992 counter, start on pps from FE5680 #1
>>> stop on gps pps from PA6H GPS module,
>>> Counter External standard is 10MHz from FE5680 #2.
>>> 
>>> The Fe5680 #2 was powered one hour before the
>>> session start, and it's mounted near the FE5680 #1,
>>> so there is some thermal stabilization
>>> in the first hours.
>>> Also I dont have any signal amplification and
>>> squaring, the trigger on the counter is set
>>> at half the pulse peak voltage, both rising
>>> edges.
>>> 
>>> Is the graph what I should expect from the gps
>>> signal, or I'm seeing some problems in the
>>> setup?
>>> 
>>> Thanks,
>>> Fabio.
>>> 
>>> Bob Camp  ha scritto:
>>> 
>>> > Hi
>>> >
>>> > That approach works well. If you have them about a half second apart
>>> > I'd stick with that setup.
>>> >
>>> > Bob
>>> >
>>> 
>>> 
>>> 
>>> This message was sent using IMP, the Internet Messaging Program.
>>> 
>>> 
>>> 
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>>> 
>>> 
>>> 
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>> 
> 
> 
> 
> This message was sent using IMP, the Internet Messaging Program.
> 
> 
> 
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Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update

[Fabio Eboli]

Thank you all for the advices.
I will prepare the setup for a longer logging session,
using an inverter and a battery for power backup.

Now I'm starting building of a clock shaper
and a divider for the 10MHz signal, I will use
7AC gates for both the squarer and divider, since I
have many of them here, no need to buy anything.

The question is: watching the previous log,
how much will the results be influenced by
the GPS antenna and it's cabling ?
(now I'm using this one:  
http://www.mirifica.it/store/gps-antenne/347-globaltop-fgpane-sma-5-m.html)


Thanks,
Fabio.

Azelio Boriani  ha scritto:


Yes, this is the typical GPS receiver PPS wander. It is usable for a GPSDO
as it seems of timing quality (the Motorola M12M is -20nS..+20nS over 10
days).
See:

http://www.jackson-labs.com/assets/uploads/main/Motorola_M12.pdf

on page 7.

On Thu, Dec 13, 2012 at 2:47 PM, Bob Camp  wrote:


Hi

Ok, those plots look much more "real". Thanks for sharing.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Fabio Eboli
Sent: Thursday, December 13, 2012 7:58 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update

Bob, timenutters
here are the first results, hope
I'm not boring the members with these
posts, for most participants these
are basic things.
Now I'm trying to understand if the
setup is working or I have to modify
some things.

The logging is at 47000 samples and going,
the script is working well now, and I dont
have glitches so far.
Raw data, time interval between the pulses:
http://www.flickr.com/photos/14336723@N08/8269800802/

Positive thing is that the drift seem consistent
with the previous decimated pulse period data.

Data corrected for linear drift and offset, the
actual values are in the graph:
http://www.flickr.com/photos/14336723@N08/8269800868/

Here I dont' like very much what I see,
but surely I'm not knowledgeable enough
to judge the data :)

Some notes for who didnt read previous posts:
Racal 1992 counter, start on pps from FE5680 #1
stop on gps pps from PA6H GPS module,
Counter External standard is 10MHz from FE5680 #2.

The Fe5680 #2 was powered one hour before the
session start, and it's mounted near the FE5680 #1,
so there is some thermal stabilization
in the first hours.
Also I dont have any signal amplification and
squaring, the trigger on the counter is set
at half the pulse peak voltage, both rising
edges.

Is the graph what I should expect from the gps
signal, or I'm seeing some problems in the
setup?

Thanks,
Fabio.

Bob Camp  ha scritto:

> Hi
>
> That approach works well. If you have them about a half second apart
> I'd stick with that setup.
>
> Bob
>



This message was sent using IMP, the Internet Messaging Program.



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Re: [time-nuts] Inexpensive modular gps with 1pps

[Hal Murray]

c...@omen.com said:
> Does this provide 10 MHz or 1pps? 

None of the low-cost units that I know about provide 10 MHz.

Most of them provide crappy timing via NMEA over a serial port.

The ones I mentioned include PPS.


-- 
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Re: [time-nuts] Inexpensive modular gps with 1pps

[Chuck Forsberg WA7KGX N2469R]

On 12/15/2012 12:19 AM, Hal Murray wrote:

gha...@gmail.com said:

You mention "low cost units which require you to add a power connector,
etc".  Could you recommend any that can be bought online?  With RS-232,
please?

There are two obvious choices.  A bit of googling may find more details
and/or other boards.

--

The new favorite is the Sure demo board.
   http://www.sureelectronics.net/goods.php?id=99
   http://www.sureelectronics.net/goods.php?id=98
(The version with the Bluetooth is cheaper than the one without.  ??)

http://www.satsignal.eu/ntp/Sure-GPS.htm

--

The old standby is the Garmin GPS-18x-LVC.  Garmin makes several versions of
the GPS-18x.
   http://www8.garmin.com/manuals/GPS18x_TechnicalSpecifications.pdf

Be sure to get the LVC version.  The others don't have a PPS.

I got mine from Provantage for roughly $70.
   http://www.provantage.com/garmin-010-00321-36~AGRMO006.htm

Setup info:
   http://time.qnan.org/
   http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm

The GPS-18 (no x) is the older version.  You probably can't find it for sale.
  It's much less sensitive, but gave much better timing over the serial port.

--

The GlobalSat MR350P is another option.  It comes with a PS2 connector, but
you can chop that off.  Their adapter cable doesn't include the PPS.

http://www.usglobalsat.com/p-58-mr-350p-bulkhead.aspx
http://www.usglobalsat.com/store/download/58/mr350p_ds_ug.pdf

That PPS is only 1 uSec wide which may be too narrow for some/most systems to
capture.

They sell a couple of adapter cables, but none of them support PPS.

You can stretch the PPS signal with the TAPR FatPPS.
   http://www.tapr.org/kits_fatpps.html



Does this provide 10 MHz or 1pps?

--
Chuck Forsberg WA7KGX N2469R c...@omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
  Omen Technology Inc  "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430


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Re: [time-nuts] Inexpensive modular gps with 1pps

[Hal Murray]

gha...@gmail.com said:
> You mention "low cost units which require you to add a power connector,
> etc".  Could you recommend any that can be bought online?  With RS-232,
> please?

There are two obvious choices.  A bit of googling may find more details 
and/or other boards.

--

The new favorite is the Sure demo board.
  http://www.sureelectronics.net/goods.php?id=99
  http://www.sureelectronics.net/goods.php?id=98
(The version with the Bluetooth is cheaper than the one without.  ??)

http://www.satsignal.eu/ntp/Sure-GPS.htm

--

The old standby is the Garmin GPS-18x-LVC.  Garmin makes several versions of 
the GPS-18x.
  http://www8.garmin.com/manuals/GPS18x_TechnicalSpecifications.pdf

Be sure to get the LVC version.  The others don't have a PPS.

I got mine from Provantage for roughly $70.
  http://www.provantage.com/garmin-010-00321-36~AGRMO006.htm

Setup info:
  http://time.qnan.org/
  http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm

The GPS-18 (no x) is the older version.  You probably can't find it for sale. 
 It's much less sensitive, but gave much better timing over the serial port.

--

The GlobalSat MR350P is another option.  It comes with a PS2 connector, but 
you can chop that off.  Their adapter cable doesn't include the PPS.

http://www.usglobalsat.com/p-58-mr-350p-bulkhead.aspx
http://www.usglobalsat.com/store/download/58/mr350p_ds_ug.pdf

That PPS is only 1 uSec wide which may be too narrow for some/most systems to 
capture.

They sell a couple of adapter cables, but none of them support PPS.

You can stretch the PPS signal with the TAPR FatPPS.
  http://www.tapr.org/kits_fatpps.html


-- 
These are my opinions.  I hate spam.




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