EQUiSat FM Decoder
This website allows you to decode receptions of Brown Space Engineering's first satellite EQUiSat by providing either an audio file or specifying a SatNOGS satellite observation to decode. You then receive an email with any data decoded from the transmission. You can also automatically submit that data to our database and have your reception posted publicly on Twitter!

This page allows you to decode an EQUiSat transmission from an NFM-demodulated (narrow frequency modulation) audio recording. We have a few recommendations for how to successfully produce these recordings:

Recommendations:

  • You can learn how to receive EQUiSat here.
  • This app is intended for you to upload your best receptions rather than prolonged pass recordings.
  • Important: the packets need to have an audio amplitude in a particular range for best decoding performance. The peak amplitude inside the packet should be about 50% of maximum; see the example recording for reference.
  • You'll need to either doppler-correct while receiving the satellite or you should tune the frequency before recording each packet burst (see below).
  • The best way to receive EQUiSat with doppler correction is to pair a software-defined radio (SDR) with a satellite tracker. GQRX and GPredict are a great combo for linux/mac, and SDRsharp and Orbitron are good for Windows. With doppler correction you can simply record NFM audio throughout the entire pass and edit it later.
  • Alternatively, if you're using a SDR and don't have doppler correction set up, the best approach is:
    1. Record the raw IQ data (baseband RF) during a pass
    2. Replay the IQ recording and visually look for packets
    3. Once you see one, visually line up the frequency you're tuned to to the center of the packet waveform
    4. Rewind the IQ recording and record the FM audio at your configured frequency
  • You can also record audio from a handheld or other hardware NFM radio, while performing manual doppler correction or using rigctl.
  • You will likely need to shorten the recording to just the best packets before submitting it here. We recommend using an audio editor such as Audacity to do this (File->Export->Export Selected Audio is a useful trick).
  • Lowering the bandwidth and applying noise filters always helps, but make sure not to significantly clip the signal.
  • For reference and comparison, this is an example of an FM recording which will be successfully decoded with no errors by this app (please don't submit it to our database). K4KDR also showed the process with HDSDR.

This app and decoder are still experimental, and currently a very clean reception is required to successfully decode a packet. So don't get discouraged, and check back in the future as we make improvements!

Note that this app will email you even if the decoder found no data or encountered an error.

Transmission Upload Form

Must be a maximum quality audio file below 20.0 MB in size and under 480s in duration, supported by libsndfile.
We don't store your email address after sending you the results.
Your name, callsign, or just the name of the receiving station. You can leave this blank if you want to be anonymous.
Your best estimate of the exact time you started receiving this audio. The more precise the better!

This page allows you to decode an EQUiSat transmission from an observation made by the SatNOGS network of open-source and publicly available ground stations. You can find observations of EQUiSat by SatNOGS stations here, and if you create an account on SatNOGS you can even schedule your own observations!

This app and decoder are still experimental, and currently a very clean reception is required to successfully decode a packet. As such many SatNOGS observations may not be decodable, but we're always making improvements!

This is an example of a SatNOGS observation that was successfully decoded with no errors (from 300-400s). Also, due to the specific amplitude requirements of this decoder, for some abnormal observations you may have more success downloading the audio file and adjusting the amplitude/duration manually.

Note that this app will email you even if the decoder found no data or encountered an error.

SatNOGS Observation Submit Form

The observation number/ID for an EQUiSat observation in the SatNOGS database. This is the number at the top of the SatNOGS observation page.
The number of seconds into the observation to start and stop decoding. Leave start blank to start at the beginning, and stop blank to use as much of the recording as permitted after the start. Note that the stop time minus the start time (the total duration) cannot exceed 480s. Also, the SatNOGS waterfall display is helpful for determining these values!
We don't store your email address after sending you the results.

Note: this make take a while to complete; this is normal while data is pulled from SatNOGS.

Built by Brown Space Engineering with generous help from Daniel Estévez