Dan's notes
  • Home
  • NTP
  • router
  • android

time

A collection of 18 posts

ntp

APU2 NTP server

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

  • Dan Drown
3 min read
gps

GPS module measurements, part 3

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

  • Dan Drown
3 min read
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

  • Dan Drown
3 min read
gps

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

  • Dan Drown
4 min read
TCXO

TCXO aging part 2

The previous data I have on aging covered 10 days, and now I want to come back to this now that more time has passed. This data is from the same Pi Hat

  • Dan Drown
1 min read
ntp

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. GPIO PPS is

  • Dan Drown
4 min read
time

Temperature compensation, part 2

In the last part, I measured the TCXO to fit a frequency vs temperature curve. Frequency vs Temperature curve Below are the final curves that I went with for the two systems, and

  • Dan Drown
4 min read
time

Temperature compensation

Temperature effects are usually the largest source of frequency changes in clocks. So I have three temperature sensors on my test system. The sensors are: one built into the stm32 chip, a TMP36

  • Dan Drown
3 min read
time

Frequency synchronization without phase in NTP

I've been working on my high accuracy RTC project. 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

  • Dan Drown
4 min read
rtc

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

  • Dan Drown
4 min read
stm32

stm32f030 devboard with TCXO

I'm interested in making a high accuracy real time clock (RTC). To experiment with the hardware I need for that, I created a development board based on the STM32F030F4P6 (which is a 20-TSSOP

  • Dan Drown
4 min read
ntp

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

  • Dan Drown
3 min read
time

Decoding WWVB, part 2

I worked on detecting the timing information from the WWVB signal. Being able to locate the start of the second is important because it is the clock the data is encoded against. I

  • Dan Drown
2 min read
time

Decoding WWVB

I've been playing with decoding WWVB. I have a random wire antenna connected to my sound card's line in jack. The sound card is a Realtek ALC1150 built into the motherboard and can

  • Dan Drown
2 min read
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

  • Dan Drown
2 min read
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

  • Dan Drown
1 min read
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

  • Dan Drown
1 min read
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

  • Dan Drown
1 min read
Dan's notes © 2019
Latest Posts Ghost