[ntp:questions] Re: Looking for time sync hardware supported under Linux for under $400?

Mark Hansen meh at NOSPAMwinfirst.com
Tue Jan 17 21:15:31 UTC 2006

On 01/17/2006 01:10 PM, Hal Murray wrote:
>>The documentation for it says that the serial interface is TTL levels
>>(which are 0-5v, if I understand correctly), rather than what would be
>>expected by a PC serial port (which are 0-15v, again IIUC).
> The transmit side of RS-232 is supposed to go below 0.  I'd
> have to find the specs to get the details.
> Common chips using flying cap switching work off 3V so they
> can only make +6V and -6V.
>>Can this just be connected to the PC serial port, or will I have
>>to build/buy a TTL -> RS-232 converter/adapter?
> Just plug it in.  It will most likely work.
> All the RS-232 receivers I've ever worked with actually switch at
> around 1.4V, the old TTL threshold.  If anybody tried to sell a chip
> that did anything else they would break all sorts of kludgy gear.

Yes, I looked closer at their specs, and see that they provide an
RS-232 version of the unit.

>>I looked through the 'Comprehensive list of clock drivers' supplied with
>>the NTP software, and didn't see this device mentioned. Is it know by
>>another name to the NTP software?
> Use the NMEA driver.

Very cool, thanks!

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