gps GPS module measurements, part 2 After the previous tests, I ordered another GPS antenna to improve the signal conditions. They're just the cheap puck style antennas with SMA connectors ($10 on Amazon), and I've put them on my
navspark Beaglebone Cape for Navspark NS-T Goal My next goal in the quest for a better NTP server is to improve the TCLKIN source. Previously, I was experimenting with TCXO's. I bought a Navspark NS-T (a timing-grade GPS receiver)
navspark TCXO + Beaglebone Black I've added support for an external clock (TCLKIN) to the Beaglebone Black timer driver. Setup I used what I had on hand to test it. I setup a Navspark microcontroller to send a
navspark Measuring Asymmetric latency via NTP, part 3 Part 1, Part 2 Varying round trip times Asymmetric latency changes NTP's calculated clock offsets. What do the offsets look like when two clocks are in sync (or always within ~200us) and the
navspark Measuring Asymmetric latency via NTP, part 2 See the first part for the math Let's use a third party (stratum 2) observer to compare the stratum 1 NTP clocks. Round trip times First, a graph of the $rtt times from
navspark Measuring Asymmetric latency via NTP Goal Learn more about the latency characteristics of my cable connection. Starting point I have a stratum 1 NTP server at home. Below is a graph of its performance. The offset between the
navspark Navspark NTP stratum 0 clock Project Goal I want to create a stratum 0 NTP clock that does not require soldering or any special hardware. It should only require a USB port and software. It should have at
arduino Navspark UART/USB bridge I created a program on the Navspark to send characters at 150 microsecond intervals and then received them on a PC. Below is a histogram of how long it took between characters: The
navspark Navspark timer drift, #2 Second run, this time comparing the Navspark's internal CPU clock against the GPS time. Samples of both clocks are taken once per second, and the amount of time that has passed is calculated
navspark Navspark timer drift The Navspark is a microcontroller with a GPS peripheral. It runs the GPS navigation/timing code as a binary-only library, and uses the Arduino IDE/environment. I have custom code printing timestamp markers