migration

This commit is contained in:
2026-05-26 20:41:02 -06:00
parent 51d096f856
commit 24387ef1e0
18 changed files with 380 additions and 380 deletions
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Added RTC (https://www.adafruit.com/product/3013)
added packages python3-smbus i2c-tools to installer
updated installer to set gpio baud to 115200
added rtc i2c overlay /boot/firmware/config.txt
removed fake-hwclock package
NEO GPS Module
Wiring
Changed to 5v mode
U-Center-2 (https://www.u-blox.com/en/u-center-2)
Changed Baudrate UART1 to 115200
Time Pulse Mode
Antenna Cable Delay set to the calculated 14ns
edited shit
baud
pins for pps
configure
unattended-upgrades
restic
all five installers
fuckin hwclock-config or whatever
1.4-rc-0
IT WORKAN WITH NEW MODULE
1.5-rc-2
updooted grafana vis
streamlined info level
collapsed all da scripts into time_fuckery.sh
1.5-rc-3
merged all da functions into time_fuckery.sh
measure offset (chrony_statistics.sh)
added Commands.md
pi image creation
1.5-rc-4
Added RTC (https://www.adafruit.com/product/3013)
added packages python3-smbus i2c-tools to installer
updated installer to set gpio baud to 115200
added rtc i2c overlay /boot/firmware/config.txt
removed fake-hwclock package
NEO GPS Module
Wiring
Changed to 5v mode
U-Center-2 (https://www.u-blox.com/en/u-center-2)
Changed Baudrate UART1 to 115200
Time Pulse Mode
Antenna Cable Delay set to the calculated 14ns
edited shit
baud
pins for pps
configure
unattended-upgrades
restic
all five installers
fuckin hwclock-config or whatever
1.4-rc-0
IT WORKAN WITH NEW MODULE
1.5-rc-2
updooted grafana vis
streamlined info level
collapsed all da scripts into time_fuckery.sh
1.5-rc-3
merged all da functions into time_fuckery.sh
measure offset (chrony_statistics.sh)
added Commands.md
pi image creation
1.5-rc-4
mostly bug fixes
+91 -91
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@@ -1,92 +1,92 @@
how do i calculate the time for a signal to travel down the wire of a gps antenna?
Calculating the time for a signal to travel down a GPS antenna cable involves understanding the **signal propagation speed**, which depends on the **velocity factor (VF)** of the cable. Heres how to do it step-by-step:
### **1. Determine the Velocity Factor (VF) of the Cable**
The velocity factor is a property of the cable and represents how fast an electrical signal travels compared to the speed of light in a vacuum (\(c = 3 \times 10^8 \, \text{m/s}\)).
Common coaxial cables used for GPS antennas:
- **RG-58**: VF ≈ **0.66** (66% of the speed of light)
- **RG-174**: VF ≈ **0.70**
- **LMR-200**: VF ≈ **0.83**
- **LMR-400**: VF ≈ **0.85**
Check your cables datasheet for the exact VF.
### **2. Calculate Signal Propagation Speed in the Cable**
The actual speed (\(v\)) of the signal in the cable is:
\[
v = \text{VF} \times c
\]
For example, with **RG-58 (VF = 0.66)**:
\[
v = 0.66 \times 3 \times 10^8 \, \text{m/s} = 1.98 \times 10^8 \, \text{m/s}
\]
### **3. Measure the Cable Length**
- Lets say your GPS antenna cable is **3 meters** long.
### **4. Calculate Signal Travel Time**
The time (\(t\)) for the signal to travel the length of the cable is:
\[
t = \frac{\text{Length}}{v} = \frac{\text{Length}}{\text{VF} \times c}
\]
For **3 meters of RG-58**:
\[
t = \frac{3 \, \text{m}}{1.98 \times 10^8 \, \text{m/s}} ≈ 15.15 \, \text{nanoseconds (ns)}
\]
### **5. Quick Formula for Practical Use**
For a given length (\(L\)) in meters and velocity factor (VF):
\[
t \, (\text{ns}) ≈ \frac{L \, (\text{m}) \times 3.33}{\text{VF}}
\]
**Example (3m, RG-58, VF=0.66):**
\[
t ≈ \frac{3 \times 3.33}{0.66} ≈ 15.15 \, \text{ns}
\]
### **Why Does This Matter for GPS?**
- **Timing Accuracy:** GPS relies on precise signal timing (errors as small as **10 ns** can cause ~3m position error).
- **Antenna Delay Calibration:** Some high-precision GPS receivers allow compensating for cable delay.
### **Final Answer**
For a **3-meter RG-58 cable**, the signal delay is **~15.15 ns**. Adjust based on your cables **VF** and **length**.
Would you like help estimating the impact on GPS positioning accuracy?
what is the 3.33 in those formulas?
Great question! The **3.33** in the simplified formula comes from the **time (in nanoseconds) it takes light to travel 1 meter in a vacuum**. Heres the breakdown:
### **Derivation of the 3.33 Constant**
1. **Speed of light in a vacuum (\(c\)):**
\[
c = 3 \times 10^8 \, \text{meters/second}
\]
2. **Time for light to travel 1 meter (in seconds):**
\[
t = \frac{1 \, \text{meter}}{3 \times 10^8 \, \text{m/s}} ≈ 3.33 \times 10^{-9} \, \text{seconds} = 3.33 \, \text{nanoseconds (ns)}
\]
3. **Generalizing for any cable length (\(L\)) and velocity factor (VF):**
The delay (\(t\)) in nanoseconds is:
\[
t \, (\text{ns}) = \frac{L \, (\text{meters}) \times 3.33 \, \text{ns/m}}{\text{VF}}
\]
- **3.33 ns/m** is the baseline delay per meter in a vacuum.
- Dividing by **VF** accounts for the slower speed in the cable.
### **Example Recap (3m RG-58, VF = 0.66)**
\[
t = \frac{3 \, \text{m} \times 3.33 \, \text{ns/m}}{0.66} ≈ 15.15 \, \text{ns}
\]
### **Why Use This Shortcut?**
- Avoids recalculating \(c\) every time.
- Converts directly to **nanoseconds** (handy for RF and GPS timing).
### **Key Notes**
- If working in **feet**, use **1.016 ns/ft** (since light travels ~1 ft in ~1.016 ns).
- For **picoseconds**, multiply by 1000 (e.g., 3.33 ns = 3330 ps).
how do i calculate the time for a signal to travel down the wire of a gps antenna?
Calculating the time for a signal to travel down a GPS antenna cable involves understanding the **signal propagation speed**, which depends on the **velocity factor (VF)** of the cable. Heres how to do it step-by-step:
### **1. Determine the Velocity Factor (VF) of the Cable**
The velocity factor is a property of the cable and represents how fast an electrical signal travels compared to the speed of light in a vacuum (\(c = 3 \times 10^8 \, \text{m/s}\)).
Common coaxial cables used for GPS antennas:
- **RG-58**: VF ≈ **0.66** (66% of the speed of light)
- **RG-174**: VF ≈ **0.70**
- **LMR-200**: VF ≈ **0.83**
- **LMR-400**: VF ≈ **0.85**
Check your cables datasheet for the exact VF.
### **2. Calculate Signal Propagation Speed in the Cable**
The actual speed (\(v\)) of the signal in the cable is:
\[
v = \text{VF} \times c
\]
For example, with **RG-58 (VF = 0.66)**:
\[
v = 0.66 \times 3 \times 10^8 \, \text{m/s} = 1.98 \times 10^8 \, \text{m/s}
\]
### **3. Measure the Cable Length**
- Lets say your GPS antenna cable is **3 meters** long.
### **4. Calculate Signal Travel Time**
The time (\(t\)) for the signal to travel the length of the cable is:
\[
t = \frac{\text{Length}}{v} = \frac{\text{Length}}{\text{VF} \times c}
\]
For **3 meters of RG-58**:
\[
t = \frac{3 \, \text{m}}{1.98 \times 10^8 \, \text{m/s}} ≈ 15.15 \, \text{nanoseconds (ns)}
\]
### **5. Quick Formula for Practical Use**
For a given length (\(L\)) in meters and velocity factor (VF):
\[
t \, (\text{ns}) ≈ \frac{L \, (\text{m}) \times 3.33}{\text{VF}}
\]
**Example (3m, RG-58, VF=0.66):**
\[
t ≈ \frac{3 \times 3.33}{0.66} ≈ 15.15 \, \text{ns}
\]
### **Why Does This Matter for GPS?**
- **Timing Accuracy:** GPS relies on precise signal timing (errors as small as **10 ns** can cause ~3m position error).
- **Antenna Delay Calibration:** Some high-precision GPS receivers allow compensating for cable delay.
### **Final Answer**
For a **3-meter RG-58 cable**, the signal delay is **~15.15 ns**. Adjust based on your cables **VF** and **length**.
Would you like help estimating the impact on GPS positioning accuracy?
what is the 3.33 in those formulas?
Great question! The **3.33** in the simplified formula comes from the **time (in nanoseconds) it takes light to travel 1 meter in a vacuum**. Heres the breakdown:
### **Derivation of the 3.33 Constant**
1. **Speed of light in a vacuum (\(c\)):**
\[
c = 3 \times 10^8 \, \text{meters/second}
\]
2. **Time for light to travel 1 meter (in seconds):**
\[
t = \frac{1 \, \text{meter}}{3 \times 10^8 \, \text{m/s}} ≈ 3.33 \times 10^{-9} \, \text{seconds} = 3.33 \, \text{nanoseconds (ns)}
\]
3. **Generalizing for any cable length (\(L\)) and velocity factor (VF):**
The delay (\(t\)) in nanoseconds is:
\[
t \, (\text{ns}) = \frac{L \, (\text{meters}) \times 3.33 \, \text{ns/m}}{\text{VF}}
\]
- **3.33 ns/m** is the baseline delay per meter in a vacuum.
- Dividing by **VF** accounts for the slower speed in the cable.
### **Example Recap (3m RG-58, VF = 0.66)**
\[
t = \frac{3 \, \text{m} \times 3.33 \, \text{ns/m}}{0.66} ≈ 15.15 \, \text{ns}
\]
### **Why Use This Shortcut?**
- Avoids recalculating \(c\) every time.
- Converts directly to **nanoseconds** (handy for RF and GPS timing).
### **Key Notes**
- If working in **feet**, use **1.016 ns/ft** (since light travels ~1 ft in ~1.016 ns).
- For **picoseconds**, multiply by 1000 (e.g., 3.33 ns = 3330 ps).
This constant simplifies real-world calculations for signal delays in cables. Let me know if you'd like further clarification!
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# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=9600
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=9600
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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#!/bin/sh
#!/bin/sh
# dev=$1
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# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=9600
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=9600
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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#!/bin/sh
#!/bin/sh
# dev=$1
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## Install
### Hardware Needed
1. Raspberry Pi of any type
2. Timing Specific GPS Module [U-BLOX ublox LEA-M8T-0-10 HUAWEI GPS Module](https://www.ebay.com/itm/134243322249)
3. High Precision RTC Module like [Adafruit DS3231 Precision RTC Breakout](https://www.adafruit.com/product/3013)
4. CR1220 Battery for RTC
5. Female to Female jumper/dupont wires
6. Raspberry Pi Case that Exposes GPIO
7. (GPS Antenna)[https://www.aliexpress.us/item/3256808971033962.html]
8. (Cable for GPS Antenna)[https://www.amazon.com/Superbat-coaxial-Bulkhead-Adapter-Equipment/dp/B07FC8PVZS?th=1]
9. (GPS Antenna Adaptor)[https://www.amazon.com/dp/B00CVR4NN0]
10. UART
11. Solder Supplies (maybe)
### Configuring Hardware
1. Install (u-center)[https://www.u-blox.com/en/product/u-center] NOT u-center 2
2. Wire UART of GPS Module to your UART
1. Change baudrate to 115200
2. enable timing mode?
3. change cable delay to calculated value
### Wiring Everything Up
#### GPS Module
1. GPS GND to RPi Physical Pin 6 (GND)
2. GPS RX to RPi Physical Pin 8 (GPIO 14 / TX (UART))
3. GPS TX to RPi Physical Pin 10 (GPIO 15 / RX (UART))
4. GPS PPS to RPi Physical Pin 12 (GPIO 18)
5. GPS VIN to RPi Physical Pin 27 (3.3 volts)
#### RTC Module
1. RTC GND to Rpi Physical Pin 9 (GND)
3. RTC SDA to RPi Physical Pin 3 (GPIO 2 / SDA1 (I2C))
4. RTC SCL to RPi Physical Pin 5 (GPIO 4 / SCL1 (I2C))
5. RTC VCC to RPi Physical Pin 1 (3.3 volts)
### Setup Pi
#### Microsd Card
1. Install [Raspberry Pi Imager](https://www.raspberrypi.com/software/) on your PC
2. Insert Microsd card to your PC
3. Run Raspberry Pi Imager
1. Choose Device (your Raspberry Pi Type)
2. Choose OS->Raspberry Pi OS (other)->Raspberry Pi OS Lite (64-bit)
3. Choose Storage (your Microsd card)
4. Configure settings as you like them
5. Burn
#### Login to Raspberry Pi
1. `curl -s https://raw.githubusercontent.com/PrincessPi3/Precision-Timekeeping-Fuckery/refs/heads/main/installer_auto.sh?nocache=$RANDOM | $SHELL`
2. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer1.sh` (will reboot)
3. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer2.sh` (will reboot)
4. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer3.sh` (will reboot)
5. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer4.sh` (will reboot)
6. `curl -s https://gitlab.com/princesspi/general-scripts-and-system-ssssssetup/-/raw/master/customscripts/install_script.sh?nocache=$RANDOM | sudo $SHELL`
7. `exec $SHELL`
8. `configure_webhook.sh`
9. `sudo reboot`
10. Grafana
1. open grafana web interface in a browser: `http://<ip>:3000`
2. username `admin` password `admin`
3. set new password
4. Dashboards->Import
1. Upload Garfana-Visualization.json
5. edit each graph and just save
11. After 24 Hours
1. `cd ~/Precision-Timekeeping-Fuckery`
2. `bash services.sh stop`
3. `bash nuke_logs.sh`
4. `bash reconfig_full.sh ./running-warn-level-conf`
5. `sudo reboot`
## Scripts
* `uninstall.sh` uninstalls everything
* `chrony_statistics.sh` uses the python script chrony_statistics.py and feeds it copies of tracking statistics to calculate offset
*`cleanup.sh` remove old files
* `dump_configs.sh` make a backup of all configs
* `full_status.sh` show status of all of the componants of Precision-Timekeeping-Fuckery one by one
* `installer_auto.sh` script to initialize the install, it is run first
* usage: `curl -s https://raw.githubusercontent.com/PrincessPi3/Precision-Timekeeping-Fuckery/refs/heads/main/installer_auto.sh?nocache=$RANDOM | $SHELL`
* `installer1.sh` first manual installer script. runs rpi-config and optionall rpi-update
* `installer2.sh` second manual installer script. performs a dist-upgrade and an autoremove
* `installer3.sh` third manual installer script. adds grafana and telegram repos, uninstalls and disables unneeded junk, installs packages, adds pps-gpio to /etc/modules if not there, autoremove, gives users the right groups
* `installer4.sh` final manual installer script. runs `reconfig_full.sh` and enables the services on boot
* `nuke_logs.sh` does just what it says on the tin
* `reconfig_full.sh` reconfigures services in one of the directories
* usage: `bash reconfig_full.sh <config_directory>`
* `services.sh` runs an operation on all of the relevant services
* usage: `bash services.sh [start|status|stop|restart|reload|enable|disable]`
* `show_running_configs.sh` shows the current config files, one by one
* `cable-delay-calc.xlsx` spreadsheet to estimate cable delay in ns
## Files
* `status.txt` this shows the progress of an ongoing install, it is automatically created at the start and deleted at the end
* `CHANGEOG.txt` this is all the latest changes
* `version.txt` version of Precision-Timekeeping-Fuckery
## Logs
### Chrony Logs
* `sudo tail -f /var/log/chrony/tracking.log`
* `sudo tail -f /var/log/chrony/statistics.log`
* `sudo tail -f /var/log/chrony/measurements.log`
### Telegraf Logs
* `sudo tail -f /var/log/telegraf/telegraf.log`
### Grafana Logs
* `sudo tail -f /var/log/grafana/grafana.log`
### Influxdb Logs
* `sudo tail -f /var/log/syslog`
### Root Crontab Logs
## Install
### Hardware Needed
1. Raspberry Pi of any type
2. Timing Specific GPS Module [U-BLOX ublox LEA-M8T-0-10 HUAWEI GPS Module](https://www.ebay.com/itm/134243322249)
3. High Precision RTC Module like [Adafruit DS3231 Precision RTC Breakout](https://www.adafruit.com/product/3013)
4. CR1220 Battery for RTC
5. Female to Female jumper/dupont wires
6. Raspberry Pi Case that Exposes GPIO
7. (GPS Antenna)[https://www.aliexpress.us/item/3256808971033962.html]
8. (Cable for GPS Antenna)[https://www.amazon.com/Superbat-coaxial-Bulkhead-Adapter-Equipment/dp/B07FC8PVZS?th=1]
9. (GPS Antenna Adaptor)[https://www.amazon.com/dp/B00CVR4NN0]
10. UART
11. Solder Supplies (maybe)
### Configuring Hardware
1. Install (u-center)[https://www.u-blox.com/en/product/u-center] NOT u-center 2
2. Wire UART of GPS Module to your UART
1. Change baudrate to 115200
2. enable timing mode?
3. change cable delay to calculated value
### Wiring Everything Up
#### GPS Module
1. GPS GND to RPi Physical Pin 6 (GND)
2. GPS RX to RPi Physical Pin 8 (GPIO 14 / TX (UART))
3. GPS TX to RPi Physical Pin 10 (GPIO 15 / RX (UART))
4. GPS PPS to RPi Physical Pin 12 (GPIO 18)
5. GPS VIN to RPi Physical Pin 27 (3.3 volts)
#### RTC Module
1. RTC GND to Rpi Physical Pin 9 (GND)
3. RTC SDA to RPi Physical Pin 3 (GPIO 2 / SDA1 (I2C))
4. RTC SCL to RPi Physical Pin 5 (GPIO 4 / SCL1 (I2C))
5. RTC VCC to RPi Physical Pin 1 (3.3 volts)
### Setup Pi
#### Microsd Card
1. Install [Raspberry Pi Imager](https://www.raspberrypi.com/software/) on your PC
2. Insert Microsd card to your PC
3. Run Raspberry Pi Imager
1. Choose Device (your Raspberry Pi Type)
2. Choose OS->Raspberry Pi OS (other)->Raspberry Pi OS Lite (64-bit)
3. Choose Storage (your Microsd card)
4. Configure settings as you like them
5. Burn
#### Login to Raspberry Pi
1. `curl -s https://raw.githubusercontent.com/PrincessPi3/Precision-Timekeeping-Fuckery/refs/heads/main/installer_auto.sh?nocache=$RANDOM | $SHELL`
2. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer1.sh` (will reboot)
3. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer2.sh` (will reboot)
4. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer3.sh` (will reboot)
5. `cd ~/Precision-Timekeeping-Fuckery && git pull; bash installer4.sh` (will reboot)
6. `curl -s https://gitlab.com/princesspi/general-scripts-and-system-ssssssetup/-/raw/master/customscripts/install_script.sh?nocache=$RANDOM | sudo $SHELL`
7. `exec $SHELL`
8. `configure_webhook.sh`
9. `sudo reboot`
10. Grafana
1. open grafana web interface in a browser: `http://<ip>:3000`
2. username `admin` password `admin`
3. set new password
4. Dashboards->Import
1. Upload Garfana-Visualization.json
5. edit each graph and just save
11. After 24 Hours
1. `cd ~/Precision-Timekeeping-Fuckery`
2. `bash services.sh stop`
3. `bash nuke_logs.sh`
4. `bash reconfig_full.sh ./running-warn-level-conf`
5. `sudo reboot`
## Scripts
* `uninstall.sh` uninstalls everything
* `chrony_statistics.sh` uses the python script chrony_statistics.py and feeds it copies of tracking statistics to calculate offset
*`cleanup.sh` remove old files
* `dump_configs.sh` make a backup of all configs
* `full_status.sh` show status of all of the componants of Precision-Timekeeping-Fuckery one by one
* `installer_auto.sh` script to initialize the install, it is run first
* usage: `curl -s https://raw.githubusercontent.com/PrincessPi3/Precision-Timekeeping-Fuckery/refs/heads/main/installer_auto.sh?nocache=$RANDOM | $SHELL`
* `installer1.sh` first manual installer script. runs rpi-config and optionall rpi-update
* `installer2.sh` second manual installer script. performs a dist-upgrade and an autoremove
* `installer3.sh` third manual installer script. adds grafana and telegram repos, uninstalls and disables unneeded junk, installs packages, adds pps-gpio to /etc/modules if not there, autoremove, gives users the right groups
* `installer4.sh` final manual installer script. runs `reconfig_full.sh` and enables the services on boot
* `nuke_logs.sh` does just what it says on the tin
* `reconfig_full.sh` reconfigures services in one of the directories
* usage: `bash reconfig_full.sh <config_directory>`
* `services.sh` runs an operation on all of the relevant services
* usage: `bash services.sh [start|status|stop|restart|reload|enable|disable]`
* `show_running_configs.sh` shows the current config files, one by one
* `cable-delay-calc.xlsx` spreadsheet to estimate cable delay in ns
## Files
* `status.txt` this shows the progress of an ongoing install, it is automatically created at the start and deleted at the end
* `CHANGEOG.txt` this is all the latest changes
* `version.txt` version of Precision-Timekeeping-Fuckery
## Logs
### Chrony Logs
* `sudo tail -f /var/log/chrony/tracking.log`
* `sudo tail -f /var/log/chrony/statistics.log`
* `sudo tail -f /var/log/chrony/measurements.log`
### Telegraf Logs
* `sudo tail -f /var/log/telegraf/telegraf.log`
### Grafana Logs
* `sudo tail -f /var/log/grafana/grafana.log`
### Influxdb Logs
* `sudo tail -f /var/log/syslog`
### Root Crontab Logs
* `sudo tail -f /var/log/root-crontab.log`
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# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=9600
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=9600
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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#!/bin/sh
#!/bin/sh
# dev=$1
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# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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@@ -1,2 +1,2 @@
#!/bin/sh
#!/bin/sh
dev=$1
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@@ -1,12 +1,12 @@
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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#!/bin/sh
#!/bin/sh
dev=$1
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rtc module
ds3231
product page: https://www.adafruit.com/product/3013
product tutorial: https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/overview
install packages python3-smbus i2c-tools
enable i2c support in raspi-config
interfacing options->i2c->
enable <Yes>
kernel module loaded by default <Yes>
check that i2c-dev is in /etc/modules
add `dtoverlay=i2c-rtc,ds3231` to /boot/firmware/config.txt
reboot
detect/test module `sudo i2cdetect -y 1`
looking for address UU AFTER configure Overlay
looking for address 68 BEFORE configure overlay
remove package fake-hwclock
remove from rc
read rtc `sudo hwclock -r`
set rtc `sudo hwclock -w`
raspberry pi RTC tutorial: https://learn.adafruit.com/adding-a-real-time-clock-to-raspberry-pi/set-rtc-time
pinout: https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/pinouts
battery: CR1220
chipset product page: https://www.analog.com/en/products/ds3231.html
chipset datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/DS3231.pdf
chipset reliability report: https://www.analog.com/media/en/technical-documentation/reliability-data/ds3231.pdf
notes:
https://serverfault.com/questions/1093101/chrony-hosting-time-with-rtc-as-authoritative-clock-on-an-air-gapped-isolated?__cf_chl_tk=G_sZX4ClltOv3fQJpH1q2a65tx4O2s_H_FObeBQ2UyU-1749831141-1.0.1.1-W0v5fl8cCrf0tIpB0pAqIb93L5MuoWeebiHm7iLGAlo
https://stackoverflow.com/questions/49730407/how-to-do-one-shot-time-sync-using-chrony
do oneshot sync?
script set every x seconds
`sudo hwclock -r`
GPS module
baudrates
1. 115200 // working
2. 230400
3. 460800
cable delay
cable is 10ft? RG-174?
14.3
velocity factors of cable forms
RG-58: VF ≈ 0.66 (66% of the speed of light)
RG-174: VF ≈ 0.70
LMR-200: VF ≈ 0.83
LMR-400: VF ≈ 0.85
formula
CD = time in nanoseconds of cable delay
L = Length of cable in UNIT
DF = delay factor in UNIT )speed of light in a vaccum used in nanoseconds per UNIT)
3.33 = ns (nanoseconds per meter)
1.016 = feet (feet per meter)
VF = velocity factor of cable (above)
CD ≈ (L*DF)/VF
CD ≈ (Length (meters) * 3.33 (baseline light speed in a vaccum ns/m)) / Velocity Factor of cable (VF)
derriving the speed of light offset
t(ns) = time in nanoseconds
c = speed of light in a vaccum in meters per second (3*(10^8) m/s)
d(m) = distance to travel in meters
rtc module
ds3231
product page: https://www.adafruit.com/product/3013
product tutorial: https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/overview
install packages python3-smbus i2c-tools
enable i2c support in raspi-config
interfacing options->i2c->
enable <Yes>
kernel module loaded by default <Yes>
check that i2c-dev is in /etc/modules
add `dtoverlay=i2c-rtc,ds3231` to /boot/firmware/config.txt
reboot
detect/test module `sudo i2cdetect -y 1`
looking for address UU AFTER configure Overlay
looking for address 68 BEFORE configure overlay
remove package fake-hwclock
remove from rc
read rtc `sudo hwclock -r`
set rtc `sudo hwclock -w`
raspberry pi RTC tutorial: https://learn.adafruit.com/adding-a-real-time-clock-to-raspberry-pi/set-rtc-time
pinout: https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/pinouts
battery: CR1220
chipset product page: https://www.analog.com/en/products/ds3231.html
chipset datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/DS3231.pdf
chipset reliability report: https://www.analog.com/media/en/technical-documentation/reliability-data/ds3231.pdf
notes:
https://serverfault.com/questions/1093101/chrony-hosting-time-with-rtc-as-authoritative-clock-on-an-air-gapped-isolated?__cf_chl_tk=G_sZX4ClltOv3fQJpH1q2a65tx4O2s_H_FObeBQ2UyU-1749831141-1.0.1.1-W0v5fl8cCrf0tIpB0pAqIb93L5MuoWeebiHm7iLGAlo
https://stackoverflow.com/questions/49730407/how-to-do-one-shot-time-sync-using-chrony
do oneshot sync?
script set every x seconds
`sudo hwclock -r`
GPS module
baudrates
1. 115200 // working
2. 230400
3. 460800
cable delay
cable is 10ft? RG-174?
14.3
velocity factors of cable forms
RG-58: VF ≈ 0.66 (66% of the speed of light)
RG-174: VF ≈ 0.70
LMR-200: VF ≈ 0.83
LMR-400: VF ≈ 0.85
formula
CD = time in nanoseconds of cable delay
L = Length of cable in UNIT
DF = delay factor in UNIT )speed of light in a vaccum used in nanoseconds per UNIT)
3.33 = ns (nanoseconds per meter)
1.016 = feet (feet per meter)
VF = velocity factor of cable (above)
CD ≈ (L*DF)/VF
CD ≈ (Length (meters) * 3.33 (baseline light speed in a vaccum ns/m)) / Velocity Factor of cable (VF)
derriving the speed of light offset
t(ns) = time in nanoseconds
c = speed of light in a vaccum in meters per second (3*(10^8) m/s)
d(m) = distance to travel in meters
t(ns) = d(m)/c
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# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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#!/bin/sh
#!/bin/sh
dev=$1
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# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# Precision Timekeeping Fuckery Additions
## GPS PPS GPIO Signal
dtoverlay=pps-gpio,gpiopin=18
## GPS GPIO UART
enable_uart=1
init_uart_baud=115200
## I2C Hardware RTC Overlay
dtoverlay=i2c-rtc,ds3231
# End Precision Timekeeping Fuckery Additions
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#!/bin/sh
# Reset the System Clock to UTC if the hardware clock from which it
# was copied by the kernel was in localtime.
dev=$1
# if [ -e /run/systemd/system ] ; then
# exit 0
# fi
# /sbin/hwclock --rtc=$dev --systz
#!/bin/sh
# Reset the System Clock to UTC if the hardware clock from which it
# was copied by the kernel was in localtime.
dev=$1
# if [ -e /run/systemd/system ] ; then
# exit 0
# fi
# /sbin/hwclock --rtc=$dev --systz
# /sbin/hwclock --rtc=$dev --hctosys