FMT Tour Transmission Format | Documentation

Transmission format Jan 4, 2026

Transmission timeline for participants

All times below are offsets from the start of a tour transmission slot. If you catch any part of the signal, you can use these points to estimate what comes next.

Total on air 21 min 42 s

Calibration part 5 min 00 s

Test intro 2 min 52 s

Pulse block spacing 138 s

On-air picture

T+00:00 Calibration 5:00

T+05:00 Test intro 2:52

T+07:52 Cycle 1 2:18

T+10:10 Cycle 2 2:18

T+12:28 Cycle 3 2:18

T+14:46 Cycle 4 2:18

T+17:04 Cycle 5 2:18

T+19:22 Cycle 6 2:20

What happens after start

Part 1

Calibration part

T+00:00 → T+05:00 · 5 min 00 s

On the published calibration frequency: calibration QST repeats, then a 60-second unmodulated reference carrier, then a short pause.

Part 2

Test intro

T+05:00 → T+07:52 · 2 min 52 s

Switch to the tour frequency, then the TEST QST block before the measurement cycles.

Cycles 1-5

Regular cycle

Every 138 s · 2 min 18 s

Pulse block, unmodulated carrier, short CW ID. Pulse blocks start exactly every 138 s.

Cycle 6

Final cycle

T+19:22 → T+21:42 · 2 min 20 s

The last cycle keeps the pulse and carrier blocks, then ends with the final sign-off.

Main reference points

T+00:00 Start Calibration part begins

T+03:56 Calibration carrier 60-second reference carrier on the published calibration frequency

T+05:01 Tour frequency Switch to the tour frequency, TEST QST follows

T+07:54 Pulse blocks First pulse block; the next ones follow every 138 s

T+08:56 Carrier blocks First carrier block; the next ones follow every 138 s

T+21:27 Final sign-off FMT TEST DE SN0FMT SK

T+21:42 End Transmission complete

Inside one cycle

Cycles 1-5

Regular cycle

2 min 18 s

≈2 s → pulse block ~60 s → ≈2 s → carrier ~60 s → ≈1 s → CW ID FMT TEST DE SN0FMT ≈13 s

Cycle 6

Final cycle

2 min 20 s

≈2 s → pulse block ~60 s → ≈2 s → carrier ~60 s → ≈1 s → final sign-off ≈15 s (the last message is always completed)

Phase boundaries are rounded orientation points.
Markers were observed in the beacon log of the tour transmission on 2026-05-01; offsets are relative to the actual transmission start. Beacon settings can change.
RF edges can move by a second or two because of keying and hardware settling.
Frequencies come from the published tour or band session data.

What this page describes

This page describes one competition transmission slot of SN0FMT — the transmission you measure in a tour. A tour can have several slots (for example on different bands); every slot follows the same sequence and is scheduled to start at its published UTC time. In CW the measurement part is announced as TEST — the traditional amateur-radio word for a contest. It is the real competition transmission, not a rehearsal.

The timing overview above shows the phases of a slot. At the end of this page you will find how calibration sessions and verification transmissions differ.

Frequencies

Calibration carrier: transmitted on the published calibration frequency. Its frequency is known exactly.
Tour carrier: the frequency you measure for FREQ. The tour schedule shows only a tuning hint with the last two digits hidden (for example 7 036 6xx).
Pulse blocks: sent in USB with a 1 kHz tone and the dial set 1 kHz below the tour carrier, so they are nominally centred on the tour carrier frequency. For FREQ always measure the unmodulated carrier — the pulse and CW segments use different signal paths and may be slightly off.

Sequence of one slot

Calibration part (on the calibration frequency): repeated QST DE SN0FMT CALIBRATION FMT, then a 60 s unmodulated calibration carrier (≈T+03:55), then a 5 s pause.
Switch to the tour frequency (≈T+05:00).
Test intro: repeated QST DE SN0FMT TEST FMT until ≈T+07:52 — use it to tune in and confirm reception.
Six measurement cycles, one every 138 s. Each cycle: pulse block (~60 s) → unmodulated carrier (~60 s) → short CW ID FMT TEST DE SN0FMT (≈13 s).
The sixth cycle ends with FMT TEST DE SN0FMT SK (≈15 s). The slot ends at ≈T+21:42.

Sync markers

Observed beacon event markers from a real tour transmission (2026-05-01). Offsets are relative to the actual transmission start recorded in the beacon log; the pulse block starts in this run were 138.0 s apart. Use these times as approximate navigation markers — RF edges can differ slightly because of keying and hardware settling.

Cycle	Pulse block starts	Carrier starts
1	T+07:54	T+08:56
2	T+10:12	T+11:14
3	T+12:30	T+13:32
4	T+14:48	T+15:50
5	T+17:06	T+18:08
6	T+19:24	T+20:26

Calibration carrier: ≈T+03:56. Switch to the tour frequency: ≈T+05:01. Final sign-off: from ≈T+21:27.

Pulse block

During a pulse block the transmitter sends a packet of three 1 kHz sine pulses, repeated every second and synchronized to GPS 1PPS:

pulse 100 ms → pause 100 ms → pulse 50 ms → pause 100 ms → pulse X ms

The first two pulses and both pauses are fixed. Use them to calibrate your measurement chain.
X (the third pulse) is the same in every packet of the tour — in all pulse blocks and all slots. It may differ between tours and is not published in advance. PULSE = X.
The whole packet is shifted from the 1PPS second by an offset that is the same for the whole tour. PPS is measured from the start of the 1PPS second to the start of the first pulse of the packet, at the 50 % envelope level.

Signal details, measured pulse shapes and the recommended 50 % / 10 % / 90 % envelope method: FMT Reference Pulse Signal Specification.

What to measure where

Metric	Where in the transmission	What to report
FREQ	Unmodulated carrier blocks of the measurement cycles	Carrier frequency of the tour transmission
PULSE	Pulse blocks	Duration of the third pulse (X)
PPS	Pulse blocks	Offset from the start of the 1PPS second to the start of the first pulse (50 % envelope)

Using the calibration carrier

Measure the 60 s calibration carrier to estimate your current receive-side frequency offset (propagation Doppler plus your receiver chain), then apply that correction to your FREQ measurement. This is optional but recommended.

The calibration carrier is not a separate contest task and does not replace the carrier blocks inside the measurement cycles: your FREQ result is based on those carrier blocks. The HF path can change between the calibration carrier and the cycles, so the correction is an estimate.

Other transmissions: calibration sessions

Calibration sessions (see the calibration schedule) use the same pulse and carrier blocks, but every parameter is known, so you can check your whole setup against the reference:

The whole session uses one published reference frequency — no switch to another frequency and no separate test part. The unmodulated carrier is exactly on the published frequency; pulses use the USB dial 1 kHz below and are nominally centred on it.
CW: QST DE SN0FMT CALIBRATION FMT, then six cycles of pulse block → carrier → FMT CALIBRATION DE SN0FMT, ending with SK. Cycles are about 144 s apart because the CW ID is longer.
The third pulse is always 25 ms and the PPS offset is 0.

The calibration session timeline below the article shows the timing of a calibration session and of the optional verification part.

Other transmissions: verification (frequency training)

After some calibration sessions a verification transmission follows on an unpublished frequency near the reference: CW FMT CHECK DE SN0FMT and three 60 s unmodulated carriers, ending with SK. When it ends, an online form opens. Submit your frequency measurement to see the reference value and your error; the reference becomes public once the session closes. Verification is training only and is not scored.

Calibration session timeline

Calibration sessions use the same pulse and carrier blocks on one published reference frequency: the third pulse is 25 ms and the PPS offset is 0. The verification part is transmitted only when a verification session was created.

Calibration 16 min 24 s

With verification 25 min 22 s

Pulse block spacing 144 s

T+00:00 Calibration QST 1:58

T+01:58 Cycles 1-5 12:00

T+13:58 Cycle 6 + sign-off 2:26

T+16:24 Pause, frequency change 0:06 optional

T+16:30 CHECK QST 2:45 optional

T+19:15 Check carriers ×3 6:07 optional

T+00:00 Start QST DE SN0FMT CALIBRATION FMT

T+02:00 Pulse blocks First pulse block; the next ones follow every 144 s

T+03:02 Carrier blocks First carrier block; the next ones follow every 144 s

T+16:03 Final sign-off FMT CALIBRATION DE SN0FMT SK

T+16:24 End of calibration Transmission ends here when there is no verification

T+16:30 Verification (optional) FMT CHECK DE SN0FMT on an unpublished frequency near the reference

T+19:15 Check carriers 60-second carriers at T+19:15, T+21:40, T+24:04

T+25:22 End with verification Transmission complete

Observed in the beacon log of the calibration session on 2026-09-14; offsets are relative to the actual transmission start. Beacon settings (message texts, repeats) can change.
RF edges can move by a second or two because of keying and hardware settling.

Transmission format

FMT Tour Transmission Format

Signal Specifications

FMT Reference Pulse Signal Specification