[time-nuts] Telecom Solutions DCD Cesium

Magnus Danielson cfmd at bredband.net
Sun Mar 19 06:32:15 EST 2006

From: Magnus Danielson <cfmd at bredband.net>
Subject: Re: [time-nuts] Telecom Solutions DCD Cesium
Date: Sun, 19 Mar 2006 11:31:11 +0100 (CET)
Message-ID: <20060319.113111.46845069.cfmd at bredband.net>

> From: "Robert Lutwak" <Lutwak at Alum.mit.edu>
> Subject: Re: [time-nuts] Telecom Solutions DCD Cesium
> Date: Sat, 18 Mar 2006 07:47:18 -0500
> Message-ID: <000501c64a8a$17b46b40$ca1b10ac at lutwakhome>
> > One more thing...
> > 
> > Some of the older 5045 modules had badly implemented hardware handshaking on 
> > the RS-232.  Sometimes it helps to wire RTS to CTS in the connector of your 
> > RS232 cable which attaches to the cesium module.  In any case, it never 
> > hurts.
> Well, now I run a Rx & Tx null-modem cable and operate the Monitor program at
> 2400 baud and that did the trick. It identifies itself as
> Symmetricom model 4201A S/N 2116 and the S/N matches what the unit says.

Unscrewing the bottom uncovered the bottom part of the Cesium platform. There
the DATUM model 4021A label is clearly shown. The 4021A platform is made
year 2000 week 19 and the DCD frame is done in year 2000 week 20. The EPROM of
the control-computer says 5045. Digging on the net the 5045 module shows up
and looks to be the same unit.

Considering that there is a number of soft configuration parameters in there,
I am considering that one of these may be at fault, forcing the loop out of
lock. I am considering writing a small program that allows me to continous dump
and control the cesium status. I have a UNIX box sitting there on the same UPS
and it is just dying for doing this task. However, I am starting to run out of
serial ports! :P Maybe I should have that second computer there anyway.

> It starts of with alarm 16, then tosses alarm 03 and then alarm 05.

I have now also seen alarm 02, Voltage difference (symmetry check of clock
transition) > 40 mV or Voltage difference (clock pedestal) > 40 mV.

> Looking in the 4065c manual (page 48) this means:
> 16: Unit restart
> 03: Voltage difference (Zeeman pedestal) > 160 mV
> 05: C-field current < 17 mA or > 20 mA
> The first one is natural when just powered on/cycled.
> The next one it reads numbers like 220 mV (the highest I recall, but I was not
> paying attention to that number this round, so I will monitor it more closely).

I might have looked on the wrong numbers here... so please silently ignore if
it does not make sense.


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