r8 - 2012-07-24 - 05:51:57 - DavidTaylorYou are here: NTP >  Support Web > InexpensiveOemGps
NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to use in a distributed denial-of-service (DDoS) attack. Please also take this opportunity to defeat denial-of-service attacks by implementing ingress and Egress filtering through BCP38.

ntp-4.2.8p3 was released on 29 June 2015, and addresses leap-second issues and a minor security issue.

Please see the NTP Security Notice for vulnerability and mitigation details.

Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.

Inexpensive OEM GPS Receivers

With PPS

Garmin GPS-18LVC

Sure Electronics GPS Evaluation board

Without PPS

Globalsat BR-355, BU-353 and other modules using the SiRF chip sets.

These don't work very well. They have two problems.

  1. First is that they have a lot of jitter/wander. (The jitter is too low frequency to easily filter out.)
  2. Second is that they have a strange off-by-a-second bug if there is a leap second pending. This graph shows both quirks.
Topic attachments
I Attachment Action Size Date Who Comment
gifgif leap-gps2.gif manage 15.2 K 2008-11-21 - 05:19 HalMurray Plot of Leap Second glitch in SiRF chip sets
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