Topic

gps

A collection of 27 issues

APU2 NTP server

I bought an apu2c0. I believe it will make a better NTP server than my other NTP servers.

RK3328 based NTP server

I got a ROC-RK3328-CC [https://libre.computer/products/boards/roc-rk3328-cc/] SBC because it has true gigabit ethernet, emmc, and USB3. These are all better I/O options than the latest Raspberry Pi 3 B+. I put a SATA hard drive in a USB3 adapter and connected it. The SBC froze

GPS module measurements, part 3

GPS module comparison: NEO-7N vs NEO-M8N

GPS module measurements, part 2

After the previous tests [https://blog.dan.drown.org/gps-module-measurements/], 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 windowsill. There's something wrong with

GPS module measurements

Starting point I got a u-blox NEO-6M and I wanted to compare it to my NS-T. Since I don't have a frequency counter, I decided to try creating one myself. The hardware I have on hand is a 72MHz STM32 devboard. I used the input capture hardware on

PPS over USB

Goal For keeping your system clock on time, you can't beat the Pulse Per Second (PPS) signals available from $10 GPS modules. They typically have better than 100 nanosecond accuracy [https://blog.dan.drown.org/gps-module-measurements-part-3/]. GPIO PPS is one of the best ways to get that timing

Frequency synchronization without phase in NTP

I've been working on my high accuracy RTC project [https://blog.dan.drown.org/stm32f030-devboard-with-tcxo/]. Here's a picture of one of the two systems: Connections The TCXO devboard, BME280, and PCF RTC are all on the i2c bus. The TMP36 sensor is hidden behind a wire

RTC comparison

Real Time Clocks I bought two high accuracy RTC (real time clock) modules and wanted to compare them. RTCs are useful for very low power clocks. They can run for years off of a coin cell battery. Both of these modules are special in they claim higher accuracy than your

GPS PPS drift when it has no signal

Question: What happens to a GPS receiver's pulse per second (PPS) when it loses signal for a long time? To answer this, I first moved the antenna away from the window and put it in an anti-static bag. I did this on the 16th at 01:02 GMT.

Beaglebone Cape for NS-T, revision 2

I'm testing the second revision of this cape now. Schematic is on github [https://github.com/ddrown/NS-T-BBB-Cape] (left: rev1, right: rev2) It's working much better than rev1, but time will tell if it has the same frequency dropouts. I've also published the NTP