[ntp:questions] Re: PPS kit and Spectracom TTS240rb

mike michael.no.spam.cook at wanadoo.fr
Wed Jul 12 05:51:45 UTC 2006

abrown at mlp.com wrote:
> Ulrich Windl wrote:
>>abrown at mlp.com writes:
>>>Fellow techs,
>>>Thanks for tuning into my issue of the day. I need to achieve 2 things.
>>>The first is to obtain and install the PPS kit onto Spectracom's
>>>TTS240rb. I spoke with the support folks a Spectracom and they
>>>suggested I post here. The second is to install the PPS kernel
>>>components on a RedHat ES 4 system running 2.6.9-XX.
> Regardless, after running the test scripts, it appeared that my kernel
> and hardware could  in fact get to within a millisecond. My next
> question was, how do I get that improvement into my environment. The
> answer from my vendor was 2 part: 1. get a PPS kit for my Spectracom
> time server 

  I think you may have misunderstood your vendor. I had a look at the
Spectracom data sheet and your device is a complete ntp server with the
extra PPS + other time code output. You do not need, and could not apply 
any modifications to the propriety Server code in the box.

  As for a PPS Kit for your linux distrib, I suggest you talk to
Redhat. They may have an implementation ready to go, else you could 
tailor  PPSkit-light yourself.

   from Spectracoms data sheet:

  Type                           Connector
  Ethernet 10/100 BaseT          RJ45 (auto sensing)
  Two RS-232 Serial Comm         DB9 female
  Two RS-485 Once-per-second     3.81mm Terminal Block
  IRIG B/E AM/TTL                BNC
  1PPS, Pulse-per-second         BNC

  so you will need hardware to convert PPS (or IRIG ) to rs232 input to 
your server. THese outputs usually put out low voltage signals not
suitable for direct connect to PC interfaces.

  10 MHz                         BNC
  Three Alarm/Programmable Timer 3.81mm Terminal Block

   So using just the NTP server over ethernet  you should be seeing sub 
millisecond accuracy. To get better you should check try the Type 4 
refclock driver which states it supports all known Spectracom servers
over the rs232 interface, where I guess there is proprierty time code
though I could not down load the manual to check what formats are available.

   I could not see a generic IRIG driver available. There must be one

and 2. get the appropriate PPS implementation for my client
> systems. In looking around the internet, I've found a few postings that
> led me to believe that people have this working for other linux
> implementations that were NTPv4 and various kernel revs.
> Is this making sense? Thanks for your time.
> Allen

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