About FMT

SP5LST FMT Project — precision HF beacon and lab in Warsaw for Frequency Measuring Tests

We build and operate a precision HF beacon and lab in Warsaw for Frequency Measuring Tests (FMT). Our goal is to give amateurs, students, and researchers a reliable, GPS-locked reference for practicing ultra-accurate frequency and timing measurements.

What we do

  • Transmit highly stable carrier and 1 PPS-aligned pulse signals for training and experiments
  • Publish schedules, tasks, and scoring so participants can measure, submit, and compare results
  • Share methods and datasets to grow a community around time-frequency metrology and HF propagation studies

Why it matters

  • Precision measurement sharpens receivers, stations, and skills
  • With a GPSDO-disciplined chain, we enable sub-Hz accuracy and repeatable timing so results are meaningful, comparable, and fun to chase

Technical Equipment

Synchronization and references

  • GPSDO: BG7TBL (10 MHz + 1 PPS) disciplining the entire chain
  • Target accuracy: sub-Hz carrier stability; pulse alignment to UTC seconds after calibrated delay compensation

Signal modes

  • Carrier mode: HP 3336A synthesizer (GPS-locked) drives the IC-7300 PA through band-filters for spectral cleanliness
  • Pulse mode: IC-7300 in USB; pulses triggered by 1 PPS with calibrated AD/DA delay correction

RF chain & control

  • Antenna: ~40 m end-fed at ~20 m AGL
  • Receiver: Kenwood TS-890S locked to GPSDO
  • Pulse source: Keysight EDU33211A into IC-7300 (SSB)
  • Switching & automation: custom low-level RF/AF switching controlled by Raspberry Pi 5 (automatic scheduling, mode control)

Measurement instruments

  • Oscilloscope: R&S RTB2002
  • Frequency counter: Agilent 53131A

Operations

  • Routine calibration runs vs. standard-frequency services (e.g., RWM, PCSK225 from Solec Kujawski)
  • Data retention and post-analysis to support scoring, peer review, and method improvement