Re: [gpsd-users] [Gpsd-users] Availability of 1PPS for Laptop users

[Dave Hart]

On Tue, Apr 17, 2012 at 07:48, Mihail Popa <address@hidden> wrote:
> Hi experts,
>
> I have to transition from my old desktop computer (with RS232 port) to a
> laptop computer (with no RS232 port)
> The GPS receiver I own connects using RS232 and provides good 1PPS signal
> (I’ve been using it already on my desktop computer…)
>
> As far as I know RS232 to USB Adapters do not propagate the 1PPS signal,
> therefore I need to find another way to provide RS232 connectivity to my
> new laptop.

Assuming the PPS signal is on the typical input (CD a.k.a. DCD carrier
detect) others' experience suggests some USB-serial chip/driver
combinations do relay the PPS properly:

http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html#usb

The add-on expresscard serial port will give better performance (both
lower latency and lower jitter) compared to connecting via a USB to
serial adapter.  It will also likely enable PPSAPI support, though
that's not needed if you're using gpsd, which can watch for the CD
input change using traditional serial I/O interfaces.

At present, there are no known USB-connected GPSes which carry through
the PPS signal, though electronically they are essentially the same as
a 232-connected GPS plus a USB to serial adapter, the PPS signal isn't
wired into the serial/USB chip.  Eric Raymond, Dave Taht, and others
working on bufferbloat are trying to change that by enlightening USB
GPS suppliers regarding the utility and near-zero incremental cost.

Cheers,
Dave Hart

P.S.  The mailing list you sent to is no longer the correct list,
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