Unknown 4-Note Ascending Signal
 | |
|---|---|
| Frequencies | 253.821 MHz,253.83 MHz |
| Frequency Range | 253.821 MHz - 253.83 MHz |
| Mode | USB, LSB |
| Modulation | — |
| ACF | — |
| Bandwidth | 9.5 kHz |
| Location | FLTSATCOM - 7 (USA-20) |
| Short Description | Signal comes from one of the 12 UHF transponders on Fleet Satcom 7. Appears to have shown up within the last couple weeks, may be a pirate channel marker or a beacon from the satellite, but it was previously not present. |
| I/Q Raw Recording | Download file |
| Audio Sample | |
Received while I was in the middle of listening to other satellites and decided to look over at FLEETSATCOM.
My location in North America makes it a relatively weak and precise target, but I managed to record it. The signal seems to be a beacon or a channel marker of some sort that repeats a set of 4 ascending tones, each with about a second of space between. Interestingly, it seems to have totally wiped out voice communications on the satellite if there were any left - both of these things may be related to the satellite's decaying stationkeeping ability as it appears to be drifting further out of GEO over South America and further over the Pacific Ocean. Given where it is at the time of writing this (QTH: CI22wj), I find it unlikely it's coming from any kind of ground source - it was also never present in the background of any of the voice communications that I've heard or that I've seen others record from the satellite and appears to have shown up fairly recently. It is present on the upper end of the satellite's 12(?) UHFUltra High Frequency (300-3000 MHz) transponders, appearing to be next to the somewhat more known "waterfall" encrypted channel. Audible in both LSBLower Side Band Modulation and USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) modes, but seems to be most audible in USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables).
