EIR-OPS-003: Start a Communication Pass


Objective

To begin a communication pass with EIRSAT-1, determine the current state of the satellite and initiate downlinks and/or other procedures.


Introduction

Using this procedure, the Operator can start a communication pass with the satellite. As part of this, the Operator will determine the current boot image of the satellite, the uptime (i.e. elapsed time since the last reboot), the Operational Mode (if applicable), the number of GRB detected in GMOD data (if applicable) and will start an LDT (if applicable).

Figure 1 presents the different possible outcomes of beginning a communication pass with EIRSAT-1. The flow chart shows the consecutive sequence of steps that must be followed depending on the Current Boot Image and Mode (i.e. platform.obc.OBC.currBootImage and mission.ModeManager.mode ) the satellite is in. The procedure below addresses all the possible branches of events.

../../../_images/CommsPassStart.png

Figure 1 - Flow chart of possible events and tasks to be followed when starting a communication pass


Procedure

A.1.

  • Get the platform.obc.OBC.currBootImage parameter frequently (i.e. with ~10 seconds between each TC).

  • Begin sending these TCs ~30 seconds before the expected time of AOS.

  • After each TC where no TM is received, set MCS’s TC sequenceNumber back to its value from before the pass (see Figure 2 for details on accessing this parameter).

  • Continue to send these TCs until:

    • TM is received from EIRSAT-1 (as per the TM/TC Details table),

    • The expected time of LOS has passed, or

    • An issue is expected with the communications chain. Refer to ssreentered for some guidance in this case and request support from senior team members!

../../../_images/MCSTCNum.png

Figure 2 - Path to the MCS TC sequenceNumber , which is used by MCS to generate TCs with HMAC authentication framing.

TC Details

MCS Operation

Get

Action/Param Name

platform.obc.OBC.currBootImage

Data Expected with TC

No

TM Details

Data Expected from TC

currBootImage ( + ACK )

Data Size

1 byte

Data Info

Index of the currently executing OBC software image

Allowed Value(s)

0, 1, 2

Where …

Image

currBootImage

failsafe

0

primary1

1

primary2

2

A.2.

  • Based on the currBootImage :

    • Ensure the appropriate SCDB is loaded into MCS, and

    • Determine what step to proceed to next using the below table.

    currBootImage

    Next step

    0

    Skip to Step A.5. As there is no ModeManager in failsafe and so ModeManager-related steps should be skipped.

    1 or 2

    Proceed to Step A.3.

A.3.

  • Invoke the mission.ModeManager.startPass action to start a communication pass.

Note

Enabling a communication pass will enable automatic and periodic transmission of live HK data from the spacecraft in place of the TM beacon data, which is transmitted outside of the pass. Automatic transmission of any on-board events raised during the pass will also be enabled throughout the pass. This on-board behavior will automatically time-out ~3 minutes after the last TC is received by the spacecraft.

TC Details

MCS Operation

Invoke

Action/Param Name

mission.ModeManager.startPass

Data Expected with TC

No

TM Details

Data Expected from TC

No ( + ACK )

A.4.

  • Get the mission.ModeManager.Mode parameter to determine the current Operational Mode of the satellite.

TC Details

MCS Operation

Get

Action/Param Name

mission.ModeManager.Mode

Data Expected with TC

No

TM Details

Data Expected from TC

Mode ( + ACK )

Data Size

1 byte

Data Info

Current Operational Mode of the satellite

Allowed Value(s)

0 - 4

Where …

Mode

Operational Mode

0

Separation Sequence

1

Commissioning

2

Nominal

3

WBC

4

Safe

Tip

The next steps of this procedure primarily instruct the Operators to Get parameters, with no instruction on what to do about the returned TM. This is because this information will be used in later steps of this procedure and/or to assist the data analyses of other procedures.


A.5.

  • Get the mission.SeparationSequence.state parameter.

TC Details

MCS Operation

Get

Action/Param Name

mission.SeparationSequence.state

Data Expected with TC

No

TM Details

Data Expected from TC

state ( + ACK )

Data Size

1 byte

Data Info

Current state of the Separation Sequence

Allowed Value(s)

00 - 09 or 66 (dec)

Expected Value(s)

66 (i.e. the finished state), if initial AOS is complete

A.6.

  • Get the core.OBT.uptime parameter to determine the elapsed time since the last reboot.

TC Details

MCS Operation

Get

Action/Param Name

core.OBT.uptime

Data Expected with TC

No

TM Details

Data Expected from TC

uptime ( + ACK )

Data Size

4 bytes

Data Info

Uptime (i.e. elapsed time since the last reboot)

Allowed Value(s)

00000000 - FFFFFFFF (hex)

Expected Value(s)

> 0

A.7.

  • Get the platform.EPS.busVoltages parameter with First row = Last row = 0 to determine the on-board voltage levels.

Danger

If busVoltages[0] <780 (dec), which corresponds to ~7.0V, the Operators are advised to postpone initiating any procedures in this pass in which the spacecraft consumes more power. This includes procedures that lead to increased RF transmissions, powering ON/enabling experiments and operating the ADCS. In the case where data downlinking is required for failure analyses, a limited amount of data downlinking is permitted.

TC Details

MCS Operation

Get

Action/Param Name

platform.EPS.busVoltages

Data Expected with TC

First Row, Last Row

Data Size

2 bytes, 2 bytes

Data Info

The first and last rows/indexes of the parameter to get

Allowed Value(s)

0 - 3

Expected Value(s)

0, 0

TM Details

Data Expected from TC

busVoltages ( + ACK )

Data Size

Int10

Data Info

busVoltages[0] = BatteryV bus, [1] = 3.3V, [2] = 5V, [3] = 12V

Allowed Value(s)

0 - 1023 (dec)

A.8.

  • Get the platform.CMC.tempaturePa parameter to determine the CMC PA temperature.

Danger

If temperaturePa >50 degrees Celsius, the Operators are advised to postpone initiating any procedures in this pass in which a significant amount of RF transmissions are likely. In this case, the Operators should monitor temperaturePa and only initiate such procedures when the parameter value falls below 45 degrees Celsius.

TC Details

MCS Operation

Get

Action/Param Name

platform.CMC.tempaturePa

Data Expected with TC

No

TM Details

Data Expected from TC

tempaturePa ( + ACK )

Data Size

signed Int8

Data Info

Temperature of the CMC power amplifier in degrees C

Allowed Value(s)

-128 - 128 (dec)

A.9.

  • If currBootImage = 0 (i.e. failsafe) in Step A.1, skip ahead to the next step.

  • Else, if GMOD has previously been experiment running, Get the payload.GMOD.GRBTriggerCount parameter to determine the current number of potential GRBs that have been detected in GMOD data.

Note

The GMOD payload does not need to be on for this Get TC. Also note that the Operator is not expected to immediately act if the GRB trigger count has increased since the last pass. The data from this TC is instead noted to facilitate future pass planning.

TC Details

MCS Operation

Get

Action/Param Name

payload.GMOD.GRBTriggerCount

Data Expected with TC

No

TM Details

Data Expected from TC

GRBTriggerCount ( + ACK )

Data Size

2 bytes

Data Info

Number of GRB triggers raised by the OBC

Allowed Value(s)

0 - 65535 (dec)

A.10.

  • The Operators should now proceed with LDTs, and/or any other procedures given the instructions in the table below. However, this should be done with care for the current state of the spacecraft (i.e. as the ‘Danger’ boxes advise in Steps A.7 and A.8.).

Important

LDTs should only be requested one at a time! When a transfer is complete, another can be started using the EIR-OPS-011: Downlink Data From Storage procedure. Get / Set TCs of other procedures may be carried out in parallel to LDTs, however, it should be noted that in this case the TM response time will be slowed.

Danger

If currBootImage = 0/failsafe, live transmission of event data is not enabled as part of this procedure, and so the operator should be careful to monitor the CMC PA temperature (i.e. platform.CMC.temperaturePa ) when downlinking data during the pass.

If currBootImage = 0/failsafe and…

state = 42/SS finished

Proceed to EIR-OPS-029: Failsafe Entered

state = 0-8/SS on-going + Failsafe’s SS was not previously finished

state = 0-8/SS on-going + Failsafe’s SS was previously finished

Proceed to ssreentered

If currBootImage = 1-2/primary and…

Mode = 4/Safe

Proceed to EIR-OPS-025: Safe Mode Entered

Mode = 1/Commissioning + 3/WBC Mode was expected

Proceed to WBC_Monitor

state = 0-8/SS on-going + Failsafe’s SS was previously finished

Proceed to ssreentered

Else…

currBootImage / state / Mode as expected

Proceed to EIR-OPS-011: Downlink Data From Storage and any other planned procedures.

Tip

If Operators are reverted to one of the unplanned procedures in the table above, data downlink instructions are provided within each procedure.


END OF PROCEDURE