Swarm-E (formerly known as e-POP)

In the spirit of making data from the Radio Receiver Instrument (RRI) onboard Swarm-E (formally known as e-POP) more accessible to the ham radio community, we have converted RRI's data into a ".raw" format so that it can be ingested into open source software such as Gqrx or GNU Radio.  We have done this for all RRI data related to the 2015, 2017, and 2018 ARRL Field Days.

We encourage everyone to help us identify hams in RRI's signal.  You can use the Gqrx tool discussed here, or you can use your own technique.  If you decode a ham's call sign, if you would like to share your technique, or if you have any comments or suggestion contact us and let us know! 

To help organize your findings, you can download a spreadhseet containing that you can fill out and send to us.  Feel free to create your own spreadsheet or modify this one.  

Swarm-E (e-POP) RRI

Swarm-E RRI is a digital radio receiver with 4 3-m monopole antennas.  In most cases, the monopoles are electronically configured into a crossed-diople configuration.  In this configuration, RRI records I/Q samples for the two dipoles.  RRI has a sampling rate of 62500.33933 Hz, and a ~40 kHz bandpass, and can be tuned to anywhere between 10 Hz and 18 MHz.  More information on Swarm-E RRI can be found in the Swarm-E RRI instrument paper or Gareth Perry's recent Radio Science article.


  • Perry, G. W., Frissell, N. A., Miller, E. S., Moses, M., Shovkoplyas, A., Howarth, A. D., & Yau, A. W. (2018). Citizen radio science: An analysis of amateur radio transmissions with e-POP RRI. Radio Science, 53, 933– 947, https://doi.org/10.1029/2017RS006496.

Data Format

Each data file contains raw 32 bit complex I/Q samples for a given RRI dipole at a given frequency.  The samples are interleaved, e.g., IQIQIQIQ... The data files do not contain any metadata.  Any information regarding the time, frequency, and corresponding RRI dipole is in the file name.  

Filename Format

The filename format gives information about the time and data of the recording, the tuned frequency, and which of RRI's dipoles the recording corresponds too.  For example, gqrx_20150628_011614_3525000_62500_RRI_Dipole1 contains data recorded on Dipole 1, starting at 01:16:14 UT on June 28, 2015, at 3525000 Hz (3.525 MHz), at a sampling rate of 62500 Hz (RRI's 62500.33933 Hz sampling rate).


We have opted to convert the data into the .raw format so that it can be ingested into Gqrx.  There are other ways of analyzing RRI's data; this is just one way which we felt was as easy first step.  We are open to posting about other techniques on the HamSCI site as well.  To help get started with Gqrx, we have developed a How to play an RRI raw IQ file on Gqrx page.

Data Files

The data files may be downloaded directly from the Zenodo repository here


A key component of the HamSCI mission is to encourage amateurs to conduct and share their own research and experiments. Larry Serra N6NC recently published two articles in QEX Magazine from his trans-North Pacific 40m propagation projects: The first, "Why Summer 40m Propagation Is So Good Between Japan and the US Pacific Coast" (QEX SEPT/OCT 2022 p.14), examined 12 years of July JA-US 40m propagation conditions and CW Skimmer results on days of JA domestic CW contests and proposed that the relatively calm water under the almost wall-to-wall summertime North Pacific HIGH pressure centers provided nearly +12dBm enhanced low-angle signal strength due to a reduction of surface reflection absorptions in the 3-ionospheric refraction, 2-sea surface reflection propagation path.

Join the WWV Amateur Radio Club, the National Institute of Standards and Technology (NIST), the Fort Collins Museum of Discovery (FCMoD), and the HamSCI for two excellent lectures to be live streamed on March 2, 2023 at 5:00PM Mountain Std Time (0000 UTC):

  • The History of WWV Frequency Broadcasts - Glenn Nelson, WWV Staff, National Institute of Standards and Technology (NIST)
  • WWV as a Beacon for Citizen Science - Dr. David Kazdan and Rachel Boedicker - Case Western Reserve University/HamSCI  Aidan Montare - NIST Boulder/HamSCI

Mike Lombardi, K0WWX, HamSCI member and Director of the National Institute of Standards and Technology (NIST) Time Realization and Distribution Group published the article Measuring the Frequency Accuracy and Stability of WWV and WWVH in ARRL's March 2023 QST. WWV and WWVH are the United States' National Time and Frequency Standards broadcast stations and are of critical importance to the HamSCI Personal Space Weather Station Project.