EIR-OPS-033: Enable/Disable RF Transmission


Objective

To disable/re-enable RF transmission from the spacecraft.


Introduction

Using this procedure, the Operator will disable transmission of data/beacons from the spacecraft over the RF link. RF transmission should not be re-enabled until a TC instructing the spacecraft to do so is sent. Therefore, we must ensure the RF inhibit persists even through reboots. To ensure this is the case, the Operator will first boot the failsafe image before disabling transmission.

Warning

This procedure should only be followed in the case where the ITU have requested that the EIRSAT-1 spacecraft cease RF transmission.


Procedure

This procedure contains the following sub-procedures:

A.I. Preparations for Tx Disable - Failsafe previously booted
A.II. Preparations for Tx Disable - Failsafe NOT previously booted
B. Tx Disable
C. Tx Enable
D. Post Tx Enable

Note

A communication window is required for all sections of this procedure.

Important

The Operator should follow Section A.I OR A.II, NOT BOTH, depending on whether the failsafe image has previously been booted or not.


A.I. Preparations for Tx Disable - Failsafe previously booted

Important

You are about to send the first TC of this procedure - Have you completed the ‘Start a Communication Pass’ procedure? A Communication Pass must be started prior to carrying out the operations planned for the pass. Don’t forget to open and set up the parameters/actions that will be used during the pass in MCS before the pass begins!

A.I.1.


A.I.2.

  • Get the mission.SeparationSequence.state parameter.

  • Confirm that the Separation Sequence is in its finished state (i.e. 0x42).

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

The current state of the Separation Sequence

Allowed Value(s)

00 - 09 or 42 (Hex)

Expected Value(s)

0x42 (Hex) / 66 (Dec)

A.I.3.

  • Get the parameter platform.EPS.actualSwitchStates with First row = 0 and Last row = 9.

  • Confirm that all PDMs are off/0.

Warning

PDM 8 is drawing parasitic power. Therefore, when you Get the platform.EPS.actualSwitchStates parameter it will always read as ON/1 even when it is powered OFF.

TC Details

MCS Operation

Get

Action/Param Name

platform.EPS.actualSwitchStates

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 - 9, 0 - 9

Expected Value(s)

0, 9

TM Details

Data Expected from TC

actualSwitchStates[0:9] ( + ACK )

Data Size

List[0:9] of booleans

Data Info

If actualSwitchStates[n] = 1, PDM n is ON

Allowed Value(s)

0,0,0,0,0,0,0,0,0,0 (all OFF) - 1,1,1,1,1,1,1,1,1,1 (all ON)

Expected Value(s)

0,0,0,0,0,0,0,1,0,0

A.I.4.

  • Get the parameter platform.ADCS.adcsModeState .

  • Confirm that the ADCS is operating in Stand-by Mode/Nadir State (i.e. 0x0000).

TC Details

MCS Operation

Get

Action/Param Name

platform.ADCS.adcsModeState

Data Expected with TC

No

TM Details

Data Expected from TC

adcsModeState ( + ACK )

Data Size

4 bytes

Data Info

The current mode (2 MSB) and state (2 LSB) of the ADCS

Allowed Value(s)

See tables below

Expected Value(s)

00000000

Where…

adcsMode (hex)

ADCS Mode

0000

Standby (Default)

0001

Detumble

0002

Spin Stabilised

5550

Test

adcsState (hex)

ADCS State

0000

Nadir (Default)

AAA8

Test

A.I.5.

  • Next, Set the mission.NoTCWatchdogManager.NoTCWatchdogTimeout parameter to 0 to disable the no TC watchdog, which will lead to reboots and wiping of persisted configuration data if not disabled.

TC Details

TMTCLab Operation

Set

Action/Param Name

mission.NoTCWatchdogManager.NoTCWatchdogTimeout

Data Expected with TC

Yes

Data Size

1 byte

Data Info

The no. of days without a TC before the no TC watchdog triggers

Allowed Value(s)

00 - FF (hex)

Expected Value(s)

0 (i.e. watchdog disabled)

TM Details

Data Expected from TC

No ( + ACK )

A.I.6.

  • Confirm the Set in the previous step with a Get (i.e. confirm the value was set successfully).


A.I.7.

  • For added mission safety while RF transmissions are disabled, and if time allows, it is advised that the Operators follow the EIR-OPS-009: Enable TC Authentication procedure to enable TC Authentication.

  • If time does not allow for TC Authentication to be enabled, skip ahead to Section B.


A.I.8.

  • As 2-way communications will be lost when RF transmissions are disabled such that the successful reception of TCs by the spacecraft may not reliably be known, it is also advised that the Operators now Set the comms.HMAC.updateSeqNum parameter to 0, to freeze the spacecraft’s TC sequence counter at a known value.

TC Details

MCS Operation

Set

Action/Param Name

comms.HMAC.updateSeqNum

Data Expected with TC

Yes

Data Size

1 byte

Data Info

Whether S/C’s TC sequence counter is incrementing (1) or not (0)

Allowed Value(s)

0 - 1

Expected Value(s)

0

TM Details

Data Expected from TC

No ( + ACK )

A.I.9.

  • Confirm the Set in the previous step with a Get (i.e. confirm the value was set successfully).


A.I.10.

  • Get the comms.HMAC.sequenceNumber parameter several times.

  • Confirm that the parameter is frozen (i.e. not incrementing) and note the parameter value for use in later steps.

Tip

This value should be used in MCS (see Figure 1.A.II) to continue communication with the spacecraft pre- and post- transmission inhibit until Step D.1, when the sequenceNumber is again thawed.

TC Details

MCS Operation

Get

Action/Param Name

comms.HMAC.sequenceNumber

Data Expected with TC

No

TM Details

Data Expected from TC

sequenceNumber ( + ACK )

Data Size

3 bytes

Data Info

S/C’s TC sequence counter

Allowed Value(s)

00 - 0xFFFFFF (Hex)

Expected Value

Not incrementing
../../../_images/MCSTCNum.png

Figure 1.A.I. - Path to the MCS TC sequenceNumber, which is used by MCS to generate TCs with HMAC authentication framing.



A.II. Preparations for Tx Disable - Failsafe NOT previously booted

Important

You are about to send the first TC of this procedure - Have you completed the ‘Start a Communication Pass’ procedure? A Communication Pass must be started prior to carrying out the operations planned for the pass. Don’t forget to open and set up the parameters/actions that will be used during the pass in MCS before the pass begins!

A.II.1.

  • Follow Sections A and B (do not follow Section C) of the EIR-OPS-024: Boot Into OBC Image procedure to boot the failsafe image.

  • Ensure the correct SCDB is loaded as part of this procedure.


A.II.2.

  • As this is the first time failsafe has been booted on-orbit, the image will boot with RF disabled and with the Separation Sequence in its 45-minute post-launch wait state.

  • Therefore, to enable RF transmissions and allow 2-way communications, the Operator should now Set the comms.TMTCBuffer.spacelinkTxEnable parameter to 1.

  • Continue to send this TC until an ACK/response is received from the spacecraft.

TC Details

MCS Operation

Set

Action/Param Name

comms.TMTCBuffer.spacelinkTxEnable

Data Expected with TC

Yes

Data Size

1 byte

Data Info

Whether RF transmission is enabled (1) or disabled (0)

Allowed Value(s)

0 - 1

Expected Value(s)

1

TM Details

Data Expected from TC

No ( + ACK )

Warning

The Operator should ONLY continue with this procedure if a response was received from the spacecraft in the previous step!!


A.II.3.

  • To determine which mission image is the current boot image on the OBC, Get the platform.OBC.obc.currBootImage parameter.

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.II.4.

  • Next, Invoke the mission.SeparationSequence.SeparationSequenceFinish action.

TC Details

MCS Operation

Invoke

Action/Param Name

mission.SeparationSequence.SeparationSequenceFinish

Data Expected with TC

No

TM Details

Data Expected from TC

No ( + ACK )

A.II.5.

  • Get the mission.SeparationSequence.state parameter.

  • Confirm that the Separation Sequence is in its finished state (i.e. 0x42).

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

The current state of the Separation Sequence

Allowed Value(s)

00 - 09 or 42 (Hex)

Expected Value(s)

0x42 (Hex) / 66 (Dec)

A.II.6.

  • Get the parameter platform.EPS.actualSwitchStates with First row = 0 and Last row = 9.

  • Ensure that all PDMs are off/0.

Warning

PDM 8 is drawing parasitic power. Therefore, when you Get the platform.EPS.actualSwitchStates parameter it will always read as ON/1 even when it is powered OFF.

TC Details

MCS Operation

Get

Action/Param Name

platform.EPS.actualSwitchStates

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 - 9, 0 - 9

Expected Value(s)

0, 9

TM Details

Data Expected from TC

actualSwitchStates[0:9] ( + ACK )

Data Size

List[0:9] of booleans

Data Info

If actualSwitchStates[n] = 1, PDM n is ON

Allowed Value(s)

0,0,0,0,0,0,0,0,0,0 (all OFF) - 1,1,1,1,1,1,1,1,1,1 (all ON)

Expected Value(s)

0,0,0,0,0,0,0,1,0,0

A.II.7.

  • Get the parameter platform.ADCS.adcsModeState .

  • Confirm that the ADCS is operating in Stand-by Mode/Nadir State (i.e. 0x0000).

TC Details

MCS Operation

Get

Action/Param Name

platform.ADCS.adcsModeState

Data Expected with TC

No

TM Details

Data Expected from TC

adcsModeState ( + ACK )

Data Size

4 bytes

Data Info

The current mode (2 MSB) and state (2 LSB) of the ADCS

Allowed Value(s)

See tables below

Expected Value(s)

00000000

Where…

adcsMode (hex)

ADCS Mode

0000

Standby (Default)

0001

Detumble

0002

Spin Stabilised

5550

Test

adcsState (hex)

ADCS State

0000

Nadir (Default)

AAA8

Test

A.II.8.

  • Next, Set the mission.NoTCWatchdogManager.NoTCWatchdogTimeout parameter to 0 to disable the no TC watchdog, which will lead to reboots and wiping of persisted configuration data if not disabled.

TC Details

TMTCLab Operation

Set

Action/Param Name

mission.NoTCWatchdogManager.NoTCWatchdogTimeout

Data Expected with TC

Yes

Data Size

1 byte

Data Info

The no. of days without a TC before the no TC watchdog triggers

Allowed Value(s)

00 - FF (hex)

Expected Value(s)

0 (i.e. watchdog disabled)

TM Details

Data Expected from TC

No ( + ACK )

A.II.9.

  • Confirm the Set in the previous step with a Get (i.e. confirm the value was set successfully).


A.II.10.

  • For added mission safety while RF transmissions are disabled, and if time allows, it is advised that the Operators follow the EIR-OPS-009: Enable TC Authentication procedure to enable TC Authentication.

  • If time does not allow for TC Authentication to be enabled, skip ahead to Section B.


A.II.11.

  • As 2-way communications will be lost when RF transmissions are disabled such that the successful reception of TCs by the spacecraft may not reliably be known, it is also advised that the Operators now Set the comms.HMAC.updateSeqNum parameter to 0, to freeze the spacecraft’s TC sequence counter at a known value.

TC Details

MCS Operation

Set

Action/Param Name

comms.HMAC.updateSeqNum

Data Expected with TC

Yes

Data Size

1 byte

Data Info

Whether S/C’s TC sequence counter is incrementing (1) or not (0)

Allowed Value(s)

0 - 1

Expected Value(s)

0

TM Details

Data Expected from TC

No ( + ACK )

A.II.12.

  • Confirm the Set in the previous step with a Get (i.e. confirm the value was set successfully).


A.II.13.

  • Get the comms.HMAC.sequenceNumber parameter several times.

  • Confirm that the parameter is frozen (i.e. not incrementing) and note the parameter value for use in later steps.

Tip

This value should be used in MCS (see Figure 1.A.II) to continue communication with the spacecraft pre- and post- transmission inhibit until Step D.1, when the sequenceNumber is again thawed.

TC Details

MCS Operation

Get

Action/Param Name

comms.HMAC.sequenceNumber

Data Expected with TC

No

TM Details

Data Expected from TC

sequenceNumber ( + ACK )

Data Size

3 bytes

Data Info

S/C’s TC sequence counter

Allowed Value(s)

00 - 0xFFFFFF (Hex)

Expected Value

Not incrementing
../../../_images/MCSTCNum.png

Figure 1.A.II - Path to the MCS TC sequenceNumber, which is used by MCS to generate TCs with HMAC authentication framing.



B. Tx Disable

B.1.

  • To now disable RF transmission, Set the comms.TMTCBuffer.spacelinkTxEnable parameter to 0 (i.e. disabled).

Warning

As RF transmission is disabled via this TC, no response/ACK is expected from the spacecraft.

TC Details

MCS Operation

Set

Action/Param Name

comms.TMTCBuffer.spacelinkTxEnable

Data Expected with TC

Yes

Data Size

1 byte

Data Info

Whether RF transmission is enabled (1) or disabled (0)

Allowed Value(s)

0 - 1

Expected Value(s)

0

TM Details

Data Expected from TC

TIMEOUT


C. Tx Enable

Note

This section, as well as the following section, should be carried out following confirmation from the ITU that EIRSAT-1 can recommence RF transmission.

C.1.

  • Compare the sequence number returned from the spacecraft at the end of Section A to that of MCS at this current time (see Figure 1.A.I/II for details on accessing this parameter).

  • Confirm that both values are represented as either decimal or hex values before then ensuring that the previously known on-board and ground segment sequence numbers match.


C.2.

  • To re-enable RF transmission, Set the comms.TMTCBuffer.spacelinkTxEnable parameter to 1 (i.e. enabled).

  • Repeatedly send this TC until an ACK is returned.

  • For every TC with no ACK/response, the Operators should reset the MCS sequence number (see Figure 1.A.I/II) to match that of the spacecraft.

TC Details

MCS Operation

Set

Action/Param Name

comms.TMTCBuffer.spacelinkTxEnable

Data Expected with TC

Yes

Data Size

1 byte

Data Info

Whether RF transmission is enabled (1) or disabled (0)

Allowed Value(s)

0 - 1

Expected Value(s)

1

TM Details

Data Expected from TC

No ( + ACK )


D. Post Tx Enable

D.1.

  • To re-enable the no TC watchdog, Set the mission.NoTCWatchdogManager.NoTCWatchdogTimeout parameter to its default value of 3 (days).

TC Details

TMTCLab Operation

Set

Action/Param Name

mission.NoTCWatchdogManager.NoTCWatchdogTimeout

Data Expected with TC

Yes

Data Size

1 byte

Data Info

The no. of days without a TC before the no-GS-TC watchdog triggers

Allowed Value(s)

00 - FF (hex)

Expected Value(s)

03 (hex)

TM Details

Data Expected from TC

No ( + ACK )

D.2.

  • Confirm the Set in the previous step with a Get (i.e. confirm the value was set successfully).


D.3.

  • Next, Set the comms.HMAC.updateSeqNum parameter to 1 to thaw the spacecraft’s TC sequence counter.

TC Details

MCS Operation

Set

Action/Param Name

comms.HMAC.updateSeqNum

Data Expected with TC

Yes

Data Size

1 byte

Data Info

Whether S/C’s TC sequence counter is incrementing (1) or not (0)

Allowed Value(s)

0 - 1

Expected Value(s)

1

TM Details

Data Expected from TC

No ( + ACK )

D.4.

  • Confirm the Set in the previous step with a Get (i.e. confirm the value was set successfully).


D.5.

  • Get the comms.HMAC.sequenceNumber parameter several times.

  • Confirm the parameter is increasing by 1 following each TC.

TC Details

MCS Operation

Get

Action/Param Name

comms.HMAC.sequenceNumber

Data Expected with TC

No

TM Details

Data Expected from TC

sequenceNumber ( + ACK )

Data Size

3 bytes

Data Info

S/C’s TC sequence counter

Allowed Value(s)

00 - 0xFFFFFF (Hex)

Expected Value

Increasing

D.6.

  • Prior to exiting failsafe and resuming nominal operations, and taking into consideration the length of time that RF Tx was disabled, the Operator should now consult with the team to determine what data downlink and health checks need to be performed to assess whether any anomalies occurred while RF transmission was disabled that could pose a risk to the mission going forward.

Important

If remaining in the failsafe image for an extended period of time, the Operator should now ensure TC Authentication is enabled.


D.7.

  • If the data confirms that the spacecraft’s health is nominal, the Operator should now follow the EIR-OPS-024: Boot Into OBC Image procedure to boot a primary image.


D.8.

  • If the primary image is successfully booted and is stable (i.e. no reboots to failsafe), the Operator can proceed with nominal operations (i.e. Nominal Mode with the experiment running and data logging on-going) using the procedures in this manual (e.g. see EIR-OPS-012: Set Up Nominal Operations ).


END OF PROCEDURE