[amsat-bb] Fwd: Polluted time server causing issues with digital modes

[Brad Brooks]

Just a reminder regarding my message: I am not criticizing or stating that
Dimension4 or any other package that uses round-robin DNS is to fault. It
is the one NTP server--rackety.udel.edu--that was causing the problem.
Remove this from your configuration options, and avoid it all together, and
your time sync package-of-choice will run fine. 73 Brad

On Sun, Apr 1, 2018 at 1:52 PM, R.T.Liddy <k8bl at ameritech.net> wrote:

> Frank,
>
> Since getting involved with FT8, I've been using
> the Meinberg Software on my computers to stay in
> sync with other stations worldwide. It has served
> me very well.
>
> Bob  K8BL
>
> https://www.meinbergglobal.com/english/productinfo/time-server.htm
> ________________________________
> From: Frank <k6fw1 at verizon.net>
> To: amsat-bb at amsat.org
> Sent: Sunday, April 1, 2018 1:41 PM
> Subject: Re: [amsat-bb] Fwd: Polluted time server causing issues with
> digital modes
>
>
>
> I looked at my log since 2009, my copy of Dimension 4 has never used
> this time sever.  The notes on this time server states closed and only
> for use by networks of 10 or more computers.  Matter of fact my
> Dimension 4 has only connected to the same time server since 2009.  I
> don't know what controls Dimension 4 and which time server it uses, but
> it does not seem to be random.  I agree that if a station is using a
> time server that is not accurate then the modes that rely on precise
> time syncing will not work.
>
> Frank
> K6FW
>
> On 3/31/18 10:37 PM, Brad WF7T wrote:
> > I am forwarding this for anyone interested. I think my discovery is
> correct
> > and invite additional review/scrutiny.
> >
> > 73 Brad WF7T
> >
> > On Sunday, April 1, 2018 at 12:21:36 AM UTC-5, Brad WF7T wrote:
> >> *I have discovered a polluted time server that is wreaking havoc with
> >> time-synced digital modes, and worse. For everyone using round-robin
> style
> >> time synchronization like Dimension 4, please remove the following time
> >> server: rackety.udel.edu <http://rackety.udel.edu>.* It is consistently
> >> sending time sync corrections that are between 10 and 41 seconds
> different
> >> than every other SNTP server in the world. This will cause your PC
> clocks
> >> to skip this amount and stay that way until another time sync occurs,
> e.g.
> >> 5 to 15 minutes later, causing another massive time correction by
> another
> >> accurate time NTP server. Please pass this information along to all
> >> digital-active hams.
> >>
> >> While this amount of time is not of any consequence for RTTY, PSK and
> the
> >> like, this behavior is detrimental to WSJT and QRSS modes. Terrestrial
> WSJT
> >> modes like FT8, WSPR, Meteor scatter MSK144, and EME modes fail to
> decode
> >> and will cause out of sequence transmissions.
> >>
> >> I also noticed a number of out-of-sequence FT8 tranmissions on 40M this
> >> afternoon (BTW, open early to EU), which clued me into the situation.
> This
> >> messed up time server could have been a contributor.
> >>
> >> *Remove or disable the following server: rackety.udel.edu
> >> <http://rackety.udel.edu>.* Apparently it has been getting increasingly
> >> worse since 3/8/2018 or so. I only discovered this tonight while I was
> >> decoding WSPR on 474.2KHz (630M) and saw a huge time jump and lack of
> >> decodes of some fairly strong signals.
> >>
> >> And yes, this is also an InfoSec problem. Time bases are important for
> >> MANY Information Security purposes, but beyond the scope of this
> discussion.
> >>
> >> Excerpts of my Dimension4 time-base logs below. Please contact me with
> >> questions/comments.
> >>
> >> 73 Brad WF7T
> >> Nashville, TN
> >>
> >> ---
> >>
> >> ... First noted occurrence in my time-base logs
> >>
> >> 2018-03-07 10:36:44.461 -7.962988e+000 rackety.udel.edu SNTP <-- 7
> second
> >> correction
> >> 2018-03-07 10:39:52.480 7.980464e+000 clock-1.cs.cmu.edu SNTP <-- fixed
> >> on next round-robin sync
> >>
> >> ... Persists for a second day, appearing to get worse
> >>
> >> 2018-03-08 09:17:25.217 -1.015543e+001 rackety.udel.edu SNTP <-- 10
> >> second correction
> >> 2018-03-08 09:20:35.240 9.963055e+000 clock-1.cs.cmu.edu SNTP <-- Fixed
> >> on next round-robin sync
> >>
> >> ... Jump ahead a week; yup, getting worse
> >>
> >> 2018-03-15 05:34:10.880 -1.761963e+001 rackety.udel.edu SNTP <--  17
> >> second correction
> >> 2018-03-15 05:37:29.176 1.812267e+001 ntp.cais.rnp.br         SNTP <--
> >> Fixed on next round-robin sync
> >>
> >> ... Skipping ahead to tonight; SNAFU
> >>
> >> 2018-03-31 23:29:34.849 -4.165045e+001 rackety.udel.edu SNTP <-- 41.6
> >> second correction!
> >> 2018-03-31 23:33:35.421 4.192192e+001 ntp2.kansas.net SNTP <-- fixed on
> >> next round-robin sync
> >>
> >>
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> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
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