NOAA Direct Sounder Broadcast (DSB)

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NOAA Direct Sounder Broadcast (DSB)
DSB.jpg
Frequencies 137.35 MHz,137.77 MHz
Frequency Range 137.35 MHz - 137.77 MHz
Mode NFM
Modulation PSK
ACF —
Emission Designator —
Bandwidth 33.5 kHz
Location Worldwide
Short Description The Direct Sounder Broadcast (DSB) was an auxiliary telemetry downlink from NOAA Polar Operational Environmental Satellites (POES), transmitted alongside Automatic Picture Transmission (APT) broadcasts.
I/Q Raw Recording Download file
Audio Sample

The Direct Sounder Broadcast (DSBDual Side Band Modulation) was an auxiliary telemetry downlink from NOAA Polar Operational Environmental Satellites (POES), transmitted alongside Automatic Picture Transmission (APT) broadcasts. "DSBDual Side Band Modulation" in this context is not to be confused with Dual Side Band modulation. On August 19th 2025, the final satellite transmitting this mode (NOAA-15) was decommissioned at 15:26 UTC, right before APT was shut down shortly after. This mode is no longer in use.

Characteristics[edit]

The DSBDual Side Band Modulation telemetry sent scientific and debugging data from the onboard TIROS Information Processor on NOAA weather satellites. The telemetry data contained information and measurements from the following onboard devices:

  • The HIRS/3 and HIRS/4 instruments, which were high-resolution infrared sounders that could be used to create a low-resolution multispectral scan of the Earth. (more info)
  • The Space Environment Monitor (SEM-2) had a Medium Energy Proton and Electron Detector (MEPED) and a Total Energy Detector (TED). This experiment measured the Sun's effect on satellite communications. (more info)
  • The experimental DCS/2 transmitter, which retransmitted signals from 401.65 MHzMegaHertz (MHz) 10^6 Hz sea buoys, Arctic fox collars, sea ice monitors, weather balloons, and more. (more info pdf)
  • The ARGOS Advanced Data Collection System (ADCS), which, amongst other uses, was used in research for tracking animal GPS collars around the world.

The telemetry signal itself was a dual sideband-modulated PSKPhase-Shift Keying signal spanning about 33.5 kHzKiloHertz (kHz) 10^3 Hz.

  • The DSBDual Side Band Modulation used PSKPhase-Shift Keying with a -67/+67 degree modulation index.
  • Transmitted Power (EOL): 1.0 watts (30dBm)
  • Radiated Power (dBm) .5 (over 90% of sphere)
  • Signal was linearly polarized

Samples[edit]

DSBDual Side Band Modulation Sample, NFMNarrowband Frequency Modulation Demodulated

DSBDual Side Band Modulation Sample, USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) Left Sideband Demodulate

Frequencies[edit]

NOAA used 137.35 MHzMegaHertz (MHz) 10^6 Hz and 137.77 MHzMegaHertz (MHz) 10^6 Hz for telemetry data.

Decoding Software[edit]

Decoding Tutorials[edit]

Decoding the NOAA Weather Satellite Telemetry Beacons

Additional Links[edit]

Additional Images[edit]

  • The DSBDual Side Band Modulation signal is circled in orange, seen to the left of a NOAA-18 APT transmission. Both signals were from the same satellite. Image from nebarinx.com

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