[Introduction] [Operations] [Payload]

Introduction

tbex_logoTBEx, the Tandem Beacon Experiment (TBEx), consists of a tandem pair of CubeSats, each carrying tri-frequency radio beacons, in near identical, low inclination orbits and a cluster of diagnostic sensors on five islands in the Central Pacific sector. The science objectives and goals of TBEx are to study how the dynamics and processes in the troposphere can act to cause variability in the behavior of the upper atmosphere and ionosphere. TBEx was developed by SRI International and MXL with funding from NASA.  TBEx was launched with support from the US Space Test Program.

Status

  • 27 August 2019 – Commissioning continues with both TBEx satellites, A and B.  The satellites are power positive and responding to ground commands.  Orbit geometry (low inclination) is presenting a challenge for our Ann Arbor ground station.  Thanks to www.satnogs.org, we are able to receive beacons globally from the satellites.
  • 25 June 10:50 AM – We are working through data and tracking now to see if TBEx signals have been received.  Our first chance to hear TBEx in Ann Arbor is tonight.
  • 25 June 4:30 AM – Launch was a success  and deployment was good!  Be sure to check online for launch photos.  Amazing.

Operations

Launch was successful!  Both TBEx satellites were deployed by the SpaceX Falcon Heavy.  The deployment times were 25 June 2019 07:13:52 and 07:08:47.

Both TBEx satellites beacon on 437.485 MHz.   Transmissions are at 9600 bps / GMSK.  Data will be encapsulated in AX.25 UI Frames.  Each spacecraft has two beacons that are described online a Google Sheet and two json files, beacon 1 and beacon 2.  The beacon period is 10 seconds, nominally.

TLEs are readily available on most TLE source sites.  The satellites are labeled TBEX-A and TBEX-B.

 

Payload

Each satellite has a tri-frequency transmitter.  The three frequencies are phase locked onboard the satellite.  As they pass through ionospheric disturbances, plasma bubbles, the phase of each transmission is affected proportionally to amount of plasma and the frequency.   Comparing the phase differences of the transmissions received by ground receivers, properties of the plasma can be inferred.  Payload transmissions will be commanded periodically during the mission.  Frequencies are given below.

  • TBEx-A: 150.012 MHz, 400.032 MHz, 1066.7520 MHz
  • TBEx-B: 149.988 MHz, 399.968 MHz, 1066.5813 MHz

Note, only the 150 and 400 MHz frequencies will be used for payload operations.

Contact Information

If you have any questions or comments, please reach out to our team below.

James W. Cutler, KF6RFX
Ph: 734-615-7238
jwcutler@umich.edu