The 17-Minute Interval — Seven Years of Data, One Unexplained Pattern

February 14th, 2019. 00:17 local time.

That's when I first caught it — a brief burst of modulated signal at 7.047 MHz, lasting exactly 3.4 seconds. I logged it, noted the timestamp, moved on. You hear weird stuff on shortwave. Pirate broadcasters, military spillover, atmospheric ducting bringing in distant stations. Par for the course.

But then it happened again. April 2nd, 2019. 00:17.

Same frequency. Same duration. Same modulation pattern — not quite AM, not quite FM, something in between that my SDR software couldn't properly decode.

47 days apart.

I've been tracking this for 7 years now. 54 occurrences. Zero deviations.

## THE PATTERN

Every 47 days, without fail:

• **00:17:00 local time** (not UTC, local — which is strange for radio phenomena)
• **7.047 MHz** (just outside the 40-meter amateur band)
• **3.4 seconds duration**
• **Identical modulation signature** each time

The signal doesn't drift. Doesn't vary with seasons or atmospheric conditions. Doesn't shift frequency like you'd expect from ionospheric propagation. It just... appears. Pulses. Stops.

Tonight was occurrence #55. I had three separate receivers running, two different antenna configurations, and a spectrum analyzer recording everything from 1-30 MHz.

I got it all.

The waveform is consistent with a digital burst transmission — possibly encrypted data, possibly a beacon. Direction finding suggests the source is approximately 15-20 miles northeast, somewhere in the national forest. But that's the problem. That puts it right in the middle of nowhere. No roads. No structures. No power lines. Just ridge after ridge of uninhabited woodland.

## THE MUNDANE EXPLANATION

Look, I'm not claiming this is anything extraordinary. There are legitimate reasons for automated transmissions:

• **Government weather stations** use scheduled transmissions
• **Seismic monitoring equipment** phones home on regular intervals
• **Old Cold War-era equipment** could still be cycling through programmed sequences
• **Amateur radio beacons** operate on automated schedules

The 47-day cycle could be tied to battery charging systems using solar power — 47 days might be the interval needed to accumulate sufficient charge for transmission during winter months.

The 00:17 timestamp could simply be when the system was first programmed, and it's maintained that schedule ever since.

All perfectly reasonable.

## BUT

I've filed FOIA requests about federal monitoring equipment in that sector. Nothing.

I've checked FCC databases for licensed beacons. Nothing.

I've hiked into those ridges three times trying to triangulate the source. The bearing keeps pointing deeper into roadless wilderness, and frankly, I'm not equipped for multi-day backcountry navigation.

And here's what keeps me up: Why 17 minutes past midnight? If you're programming an automated system, you use round numbers. 00:00. 00:15. 00:30. You don't use 00:17 unless that number means something specific.

Unless it's a marker.

I've got 7 years of clean recordings now. The signal-to-noise ratio is getting worse — more interference, more competing transmissions crowding the bands — but the pattern holds. Another entry for the log.

Maybe it's just an old repeater nobody remembers installing. Maybe it's been pulsing out there since before I moved here, and I'm just the first person paranoid enough to notice.

Or maybe somebody — or something — is counting.

Is there legitimate equipment that would transmit on this exact schedule?

Should I organize a proper expedition to find the source?

Stay vigilant.

—JohnD_TN