[ntp:questions] Announcing the TAPR "FatPPS" Pulse Stretcher

John Ackermann N8UR jra at febo.com
Sun Jan 7 15:35:09 UTC 2007

Is your PPS signal too short to trigger your serial port?  Is that
what's troubling you, Bunkie?

If so, the new TAPR FatPPS is the answer you've been looking for...

The FatPPS is a DB-9 "dongle" that implements a pulse stretcher.  Input
signals as short as 20 nanoseconds produce an output pulse about 30
milliseconds wide (the width can be changed by changing a few component
values).  It can be powered from the host computer's serial port, and so
requires no external connections at all.  It works with either TTL or
RS-232 level input pulses (the output is always TTL level), and can
invert input or output pulse polarity if needed.

I designed the FatPPS because the ~20 microsecond wide PPS signals from
several of my time sources (like the Z3801A GPSDO, and HP frequency
standards) was too short to reliably work with the serial ports on my
NTP servers.  Hopefully, it will be of use to some of you as well.

The FatPPS is available only as a fully assembled and tested unit, and
is shipping now.  The price is $44 for TAPR members, and $49 for

There are more details, and you can place an order, at
http://www.tapr.org/kits_fatpps.html.  You can view the installation and
operations manual (which is still a work in progress) at

Thanks for the interruption.


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