RHOK-SAT identification

Satellites & Observations
1

Hi everybody!

I’m part of the RHOK-SAT CubeSat team. Unfortunately, we haven’t been able to establish comms with our satellite (we suspect there may be issues with our ground station), and, though it’s had a short life, it is now close to re-entry. We are wondering if anyone would be interested in pinging it via a command that we would provide as a burst recording or data packet, as a last attempt to determine the satellite’s status. Regulations-wise, the satellite operates under both amateur and experimental authority, and any licensed amateur radio operator can transmit to it under the authority of their own personal amateur license.

These are the basic details:

  • Uplink:
    • VHF
    • FSK-G3RUH modulation
    • 9600 bps data rate
  • Downlink:
    • UHF
    • BPSK-G3RUH modulation
    • 9600 bps data rate

Part of the challenge lies in the fact that we are not confident that RHOK-SAT corresponds to OBJECT-XT (NORAD ID 66907), which is what is tracked on SatNOGS. We launched on NG-23, alongside five other CubeSats: CU-ALPHA, ContentCube, EagleSat-2, Foras Promineo, and SilverSat (shout-out to the SilverSat team, who have been incredibly supportive and helpful during this process). Like RHOK-SAT, four other of these satellites have not been confirmed on Space-Track. Thus, we suspect that RHOK-SAT could be any of those. Our main candidates, which RHOK-SAT deployed together with, are:

  • OBJECT-XU (NORAD ID 66908; corresponds to CU-ALPHA on SatNOGS. The satellite makes use of a satellite constellation for comms, which makes precise tracking difficult. However, its team narrowed its position to that of either 66907 or 66908.)
  • OBJECT-XY (NORAD ID 66912; corresponds to ContentCube on SatNOGS. We believe that comms have not been established.)

The remaining two candidates, which deployed 90 minutes (or, one orbit) after us, are:

  • OBJECT-XW (NORAD ID 66910; corresponds to EagleSat-2 on SatNOGS. We believe that comms have not been established.)
  • OBJECT-XX (NORAD ID 66911; corresponds to Foras Promineo on SatNOGS. The satellite makes use a satellite constellation for comms, which makes precise tracking difficult. However, its team more closely matched its position to this object over XW.)

I don’t believe it’s likely that RHOK-SAT corresponds to XW or XX, given the deployment timing; however, since 90 minutes closely corresponds to the duration of one orbit, perhaps they could have ended up overlapping(?). I do not know how NORAD identification works.

Thank you for your consideration!

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2

this sat remind me about “spam obs” :pensive_face:

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@joserpm Thanks for the additional information. Do I understand it correctly that you never achieved successful communication with the satellite or do you only lost contact recently?

In SatNOGS DB one transmitter is labeled “Mode U - BPSK9k6 - Beacon” so did you expect the satellite to sent out a beacon at a regular interval?

What are the exact up- and downlink frequencies?

Can you confirm that any of the observations marked as good in network are actually from RHOK-SAT?

You mentioned that you suspect issues with your ground station, did you conduct end-to-end tests with the satellite before the checkout or do you have an engineering model you can test the GS with?

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@julianharbeck That is correct, successful communication was never achieved.

We did expect a single beacon every 10 minutes (which is pretty limiting, I know), but we did not receive any on our ground station. I can affirm that the observations marked as good in the network are NOT confirmed to be from RHOK-SAT, despite there being a signal.

We did conduct successful end-to-end tests with the satellite before and even after its antennas were stowed, albeit at a close range. We also have an engineering model and have tested comms with it at a distance of about 300 meters.

The exact frequencies are as follows:
Downlink: 435.425 MHz
Uplink: 145.83 MHz

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I am aware of that situation, and I sincerely apologize for it

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