[ntp:questions] Is there an easier way to hook a GPS clock to NTP or a free shortwave audio line level out?

Nate Homier ntp at universal-mechanism.org
Wed Dec 16 01:11:45 UTC 2015


OK!  I'm going with the Raspberry PI B+ with a plug in GPS receiver.  
So on the http://ava.upuaut.net store it list the GPS receiver then down 
below it list the nine related products.  So if I understand right I 
want the B+ version.  The case looks cool and I just need the case and 
the 25mm M3 Standoff Kit for Geaux Robot Case.  What about Stacking 
header kit for Raspberry Pi+ do I need it and do I need this one too, 
11mm Stand off kit for Raspberry Pi+?  Which of those three GPS antennas 
do I need and what's the difference between them.

On 12/16/2015 1:20, Mike Cook wrote:
> Hi Nate,
>
>   I think you can forget about using your radio as the E1’s lowest
> band is from 100KHz and WWVB which is what you want for timing is on
> 60KHz. I don’t know of any FM station time decoders.
>
> After that cold shower, the options are limitless wth quite a number
> entailing gluing small bits.
> I have gone the way of gluing bits and I have a lot of them.
>
> Your stats are are bad, due probably to the >2:1 asymmetry in
> upload/download rates on 4G plus latency on the WIFI. You might also
> be compounding that with power saving on your system though you don’t
> say how that is configured.
>
> If you want low budget, and have no better internet access you might
> get by with a cheap PCI-E GPS such as Ublox GPS B39 PCI-5S-1-500 at <
> $10 delivered from the auction site, coupled to a mini PCI-E to PCI-E
> adapter (ex 181622523046 on the same site) for $5 delivered, an 
> active
> SMA antenna with say 5m of cable , another $10 plus
> an SMA pigtail to replace the RP-SMA at a couple of $ 
> (ex.281842153844).
> Link all that up and you will have an NMEA ref clock (over what will
> look like a USB serial port to your OS) that should give you low ms
> accuracy and stability for less than $50.
> The GPS receiver seems to have a 4Hz update rate which is not useful,
> but it can be reconfigured to 1Hz (see
> 
> <http://emerythacks.blogspot.fr/2013/01/u-blox-pci-5s-cheap-gps-module-for-your.html>
> ) with Ublox’s U-Center free software. That runs on windows only, but
> should run under wine in linux or maybe you can dual boot your system
> or ask a friend.
>
> I prefer to have my time servers independent of application workload
> , so I have many minis dedicated to that.
> A good cheap one is a Raspberry PI B+ with a plug in GPS receiver
> such as
> 
> <http://ava.upuaut.net/store/index.php?route=product/product&path=59_60&product_id=117>
> which has few bits and only one connector to solder. If you ask
> nicely, the seller will probably do it for you. If you add a usb wifi
> dongle you won’t need cabling but you get better latency with cable,
> so I would use that as you have ethernet on your box. The advantages
> here are that you can leave it on all the time, and it will have 1PPS
> ref clock, so you have microsecond accuracy and stability. Well I do
> with that config.  With a case, antenna etc I think you can get a
> clean setup for < $150.
>
> Of course you can do cheaper with bits. Take your choice.
>
> Caveat:
>   As you have a crappy internet connection , even with a really
> accurate inboard or external time source, it will be only ONE. This 
> is
> not a good config . You really need a minimum of 3 .
> How much would a proper internet connection cost you?
>
> You seem to be between a rock and a hard place.
>
> Regards,
> Mike
>
>> Le 13 déc. 2015 à 17:06, Nate Homier <ntp at universal-mechanism.org> a 
>> écrit :
>>
>> I am using a system76.com Wild Dog Pro desktop computer running 
>> Ubuntu 15.10, I bought it in December 2015.  It has no serial port.  I 
>> have a Shortwave radio if that will work to hook up to NTP.  
>> Researching the net reveals many howto for hooking up GPS OEM radios.  
>> This usually involves soldering, cutting and working with little tiny 
>> things, all of which I am terrible at.  I have heard of GPS radios 
>> that plug into your PCI-E slot, now that sounds cool, but pricey.
>>
>> Does anybody have any recommendation as to how I can turn myself 
>> into an accurate stratum 0 or 1 client, I am not interested in being
>
> Stratum 0 is the reference clock, Atomic, GPS, WWVB or whatever  . It
> is what makes an NTP source Stratum 1, so if you have a ref clock 
> then
> your box will  default to stratum 1 while the ref clock is reachable.
> You can fudge stratum levels in the config, but it is unusual outside
> testing.
>
>> a server.  In case your wondering why, I don't know why, I do have 
>> an official diagnosis of OCD, that might explain it.  Not accurate 
>> time bothers me a lot.
>>
>> I have an Eton E1 HF receiver that keeps it's clock accurate via the 
>> HF time bands, but not the LF band, strange, on the other hand your 
>> guaranteed to get an HF signal worldwide as opposed to LF.  It also 
>> has an audio line out and does anybody have any experience with line 
>> level audio for time keeping.  Maybe I should start there before 
>> forking over the cash for some project I can't finish.
>>
>> Here's what I'm willing to do.
>>
>> Do the shortwave radio thing first.  Free and what I learn from it I 
>> can apply to below.
>>
>> Buy an PCI-E port serial card, one that you guys tell me to buy, 
>> budget $75
>> Buy an GPS PCI-E card or external device.  I can't give you a figure 
>> for what I'm willing to pay because I have no idea what they cost.
>>
>> Just doing this for fun.  Love NTP.
>>
>> Currently I am getting Internet through my Verizon Samsung Galaxy S6 
>> Edge WiFi hotspot.  -102 dBm and 38 asu signal, poor signal for 4G 
>> LTE.  Once I get up in the morning I turn off the Internet at about 11 
>> am and the computer won't see a connection again until 8 or 9 pm.  So 
>> NTP is only connected during the night when I'm sleeping.  Anybody 
>> know how I can keep track of clock drift when NTP gets woken up at 
>> night, be interesting to see how accurate the motherboard is.
>>
>
> NTP’s drift file will give you that info , though your connection
> looks so bad that it may not be that good a figure. You really need
> stable sources for to enable NTP to calculate it.
>
>> My current NTP stats.
>>
>> First one is from peer.awk
>>
>> ident                       cnt  mean     rms     max      delay    
>> dist     disp
>> 
>> ==========================================================================
>> 208.75.89.4                 21   30.724   60.139  161.716  103.967  
>> 989.601  149.718
>> 2604:a880:800:10::bc:c00d   19    8.736   16.624   32.476  134.039  
>> 499.117   42.186
>> 50.116.38.157               18   19.069   23.196   46.512  141.819  
>> 495.233   44.446
>> 2001:67c:1560:8003::c7      17   -2.631   18.085   41.863  204.340  
>> 173.570   23.222
>> 104.41.150.68               18   37.286   26.949   50.019  147.775  
>> 174.419   39.181
>>
>>
>> nate at frontier:~$ ntpq -p
>>     remote           refid      st t when poll reach   delay   
>> offset  jitter
>> 
>> ==============================================================================
>> +deekayen.net    152.2.133.52     2 u  554 1024  377  135.533  
>> -23.196  82.525
>> *time.tritn.com  198.60.22.240    2 u  531 1024  377   82.637  
>> -26.905  62.751
>> +2604:a880:800:1 131.234.137.24   2 u  592 1024  377  149.243  
>> -23.740  63.528
>> +104.41.150.68   129.6.15.30      2 u 1007 1024  377  109.755    
>> 5.461  87.911
>> +golem.canonical 170.224.124.217  2 u  488 1024  377  182.265  
>> -44.495 158.015
>>
>> Sincerely Nate.



More information about the questions mailing list