This "project" provides status monitoring and graph visualization for two Raspberry Pi devices running ADS-B flight tracking and NTP time server services.
ADS-B (Automatic Dependent Surveillance-Broadcast)
Aircraft broadcast their position, altitude, speed, and flight number via radio. A Raspberry Pi with a software-defined radio receiver picks up these signals and displays live air traffic on a map.
NTP (Network Time Protocol)
A protocol used to synchronize computer clocks over a network. This server uses a GPS receiver as a precise time source and acts as Stratum 1 to provide accurate time to other devices on the local network.
Pi 3B — ADS-B Feeder
This is an example of my "radar" screen with info I get from the ADS-B signal. (refreshed every 10 min)
Updated: 2026-09-26 01:43
Pi 5 — NTP Server
An example of some information the chrony software provides on the Pi 5 about the NTP server with GPS timing. (refreshed every 5 min)
=== CHRONY SOURCES (GPS & PPS only) ===
.-- Source mode '^' = server, '=' = peer, '#' = local clock.
/ .- Source state '*' = current best, '+' = combined, '-' = not combined,
| / 'x' = may be in error, '~' = too variable, '?' = unusable.
|| .- xxxx [ yyyy ] +/- zzzz
|| Reachability register (octal) -. | xxxx = adjusted offset,
|| Log2(Polling interval) --. | | yyyy = measured offset,
|| \ | | zzzz = estimated error.
|| | | \
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#x GPS 0 4 377 11 -210ms[ -210ms] +/- 200ms
#* PPS 0 4 377 11 +429ns[ +150ns] +/- 138ns
=== CHRONY TRACKING ===
Reference ID : 50505300 (PPS)
Stratum : 1
Ref time (UTC) : Fri Sep 25 23:40:51 2026
System time : 0.000000391 seconds slow of NTP time (*)
Last offset : -0.000000419 seconds (*)
RMS offset : 0.000002338 seconds
Frequency : 0.806 ppm slow (*)
Residual freq : -0.003 ppm
Skew : 0.124 ppm
Root delay : 0.000000001 seconds
Root dispersion : 0.000012645 seconds
Update interval : 16.0 seconds
Leap status : Normal
(*) values used in NTP graphs
=== CHRONY SOURCESTATS (GPS & PPS only) ===
.- Number of sample points in measurement set.
/ .- Number of residual runs with same sign.
| / .- Length of measurement set (time).
| | / .- Est. clock freq error (ppm).
| | | / .- Est. error in freq.
| | | | / .- Est. offset.
| | | | | | On the -.
| | | | | | samples. \
| | | | | | |
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
GPS 64 48 1007 -37.241 59.697 -174ms 40ms
PPS 6 4 80 -0.003 0.110 -8ns 848ns
chronyc (chrony) version 4.3 (+READLINE +SECHASH +IPV6 -DEBUG)
Generated at 2026-09-26 01:41:03
Updated: 2026-09-26 01:41
