FSK Data Rollercoaster

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NFMNarrowband Frequency Modulation Baby Monitor
Datarollercoaster.png
Frequencies 864.878Mhz864,878,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
864,878 kHzKiloHertz (kHz) 10^3 Hz
Frequency Range 864878000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).864,878 kHzKiloHertz (kHz) 10^3 Hz
864.878 MHzMegaHertz (MHz) 10^6 Hz
864878000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).864,878 kHzKiloHertz (kHz) 10^3 Hz
864.878 MHzMegaHertz (MHz) 10^6 Hz
Mode USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables)
Modulation NFMNarrowband Frequency Modulation
Bandwidth 32 kHzKiloHertz (kHz) 10^3 Hz32,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
0.032 MHzMegaHertz (MHz) 10^6 Hz
32 kHzKiloHertz (kHz) 10^3 Hz
0.032 MHzMegaHertz (MHz) 10^6 Hz
32 kHzKiloHertz (kHz) 10^3 Hz
0.032 MHzMegaHertz (MHz) 10^6 Hz
Location Denmark
Short Description Recording using USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables); baby monitor system is NFMNarrowband Frequency Modulation.
I/Q Raw Recording
Audio Sample

Identified as baby monitor; model unknown. FMFrequency Modulation modulated voice was received in USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) mode; recording and waterfall saved, will upload later.

Monitor sends beacon bursts while idling (6 second interval, 1.5 second burst); beacon contains audio modulation. Continuous audio transmission is volume level triggered. In most observed cases, the beacon swing alternate between left to right and right to left; after a triggered transmission, the signal will swing right twice in a row. In some cases, the beacons will continuously swing left only, except for the single beacon burst after a triggered audio transmission. I think these differing beacon swing modes describes the battery charge.