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Tutorial: Downlink data from public satellites

  • Artikkeli

You can communicate with satellites directly from Azure by using the Azure Orbital Ground Station service. After you downlink data, you can process and analyze it in Azure.

In this tutorial, you'll learn how to:

  • Create a spacecraft for select public satellites.
  • Prepare a virtual machine (VM) to receive downlinked data.
  • Configure a contact profile for a downlink mission.
  • Schedule a contact with a supported public satellite using Azure Orbital Ground Station and save the downlinked data.

Azure Orbital Ground Station supports several public satellites including Aqua, Suomi NPP, JPSS-1/NOAA-20, and Terra.

Prerequisites

Sign in to Azure

Sign in to the Azure portal - Orbital.

Create a spacecraft resource

  1. In the Azure portal search box, enter Spacecrafts. Select Spacecrafts in the search results.
  2. On the Spacecrafts page, click Create.
  3. Choose which public satellite to contact: Aqua, Suomi NPP, JPSS-1/NOAA-20, or Terra. The table below outlines the NORAD ID, center frequency, bandwidth, and link direction and polarization for each satellite. Refer to this information in the following steps and throughout the tutorial.
Spacecraft NORAD ID Center Frequency (MHz) Bandwidth (MHz) Direction Polarization
Aqua 27424 8160 15 Downlink RHCP
Suomi NPP 37849 7812 30 Downlink RHCP
JPSS-1/NOAA-20 43013 7812 30 Downlink RHCP
Terra 25994 8212.5 45 Downlink RHCP

  1. Search for your desired public satellite in CelesTrak and identify its current Two-Line Element (TLE).

    Note

    Be sure to update this TLE to the most current value before you schedule a contact. A TLE that's more than two weeks old might result in an unsuccessful downlink.

    Read more about TLE values.

  2. In Create spacecraft resource, on the Basics tab, enter or select the following information:

    Field Value
    Subscription Select your subscription.
    Resource Group Select your resource group.
    Name Enter the name of the public spacecraft.
    Region Select West US 2.
    NORAD ID Enter the NORAD ID from the table above.
    TLE title line Enter AQUA, SUOMI NPP, NOAA 20, or TERRA.
    TLE line 1 Enter TLE line 1 from CelesTrak.
    TLE line 2 Enter TLE line 2 from CelesTrak.

  3. Click Next. In the Links pane, select Add new Link.

  4. In the Add Link page, enter or select the following information:

    Field Value
    Name Enter Downlink.
    Direction Select Downlink.
    Center Frequency Enter the center frequency in MHz from the table above.
    Bandwidth Enter the bandwidth in MHz from the table above.
    Polarization Select RHCP.

  5. Click Review + create. After the validation is complete, click Create.

If your spacecraft resource exactly matches the information in Step 3, your spacecraft is automatically authorized at Microsoft ground stations.

Note

You can confirm that your spacecraft resource is authorized by checking that the Authorization status shows Allowed on the spacecraft's overview page.

Prepare your virtual machine and network to receive public satellite data

  1. Create a virtual network to host your data endpoint virtual machine (VM) using the same subscription and resource group where your spacecraft resource is located.

  2. Create a virtual machine within the virtual network that you created using the same subscription and resource group where your spacecraft resource is located. Ensure that this VM has the following specifications:

    • Under the Basics tab:
      • Image: the operating system is Linux (Ubuntu 20.04 or later).
      • Size the VM has at least 32 GiB of RAM.
    • Under the Networking tab:
      • Public IP: the VM has internet access for downloading tools by having one standard public IP address.

    Tip

    The public IP address here is only for internet connectivity, not contact data. For more information, see Default outbound access in Azure.

  3. Navigate to the newly created VM. Follow the instructions linked in Step 2 to connect to the VM. At the bash prompt for your VM, enter the following commands to create a temporary file system (tmpfs) on the VM. This VM is where the data will be written to avoid slow writes to disk.

    Note

    This command references Aqua. Edit the command to reflect the public spacecraft you're using.

    sudo mkdir /media/aqua
sudo mount -t tmpfs -o size=28G tmpfs /media/aqua

  4. Enter the following command in your VM to ensure that the Socat tool is installed on the machine:

    sudo apt install socat

  5. Follow instructions to delegate a subnet to Azure Orbital Ground Station.

  6. Follow instructions to prepare your VM endpoint. Enter the following command in your VM to set the MTU level to 3650:

    sudo ifconfig eth0 3650

Configure Event Hubs for antenna telemetry

To receive antenna telemetry during contacts with your selected public satellite, follow instructions to create and configure an Azure event hub in your subscription.

  1. In the Azure portal's search box, enter Contact Profiles. Select Contact Profiles in the search results.

  2. On the Contact Profiles page, click Create.

  3. In Create Contact Profile resource, on the Basics tab, enter or select the following information:

    Field Value
    Subscription Select your subscription.
    Resource group Select your resource group.
    Name Enter [Satellite_Name]_Downlink, e.g., Aqua_Downlink.
    Region Select West US 2.
    Minimum viable contact duration Enter PT1M.
    Minimum elevation Enter 15.0.
    Auto track configuration Select X-band.
    Send telemetry to Event Hub? Select Yes.
    Event Hubs Namespace Select an Azure Event Hubs namespace to which you'll send telemetry data for your contacts. You must select a subscription before you can select an Event Hubs namespace.
    Event Hubs Instance Select an Event Hubs instance that belongs to the previously selected namespace. This field appears only if you select an Event Hubs namespace first.
    Virtual Network Select the virtual network that you created earlier.
    Subnet Select the delegated subnet that you created earlier. This field appears only if you select a virtual network first.

  4. Click Next. In the Links page, click Add new Link.

  5. On the Add Link page, enter or select the following information:

    Field Value
    Name Enter a name for the link, e.g. Aqua_Downlink
    Direction Select Downlink.
    Gain/Temperature Enter 0.
    EIRP in dBW Only applicable to uplink. Leave blank.
    Polarization Select RHCP.

  6. Click Add Channel. In the Add Channel pane, add or select the following information:

    Field Value
    Name Enter a name for the channel, e.g Aqua_Downlink_Channel.
    Center Frequency (MHz) Enter the center frequency in MHz. Refer to the table above for the value for your selected spacecraft.
    Bandwidth (MHz) Enter the bandwidth in MHz. Refer to the table above for the value for your selected spacecraft.
    Endpoint name Enter the name of the virtual machine that you created earlier.
    IP Address Enter the private IP address of the virtual machine that you created earlier.
    Port Enter 56001.
    Protocol Enter TCP.
    Demodulation Configuration Type Select Preset Named Modem Configuration.
    Demodulation Configuration Select the demodulation configuration for your selected public satellite. Refer to configure the modem chain for details.
    Decoding Configuration Leave this field blank.

  7. Click Submit to add the channel. Click Submit again to add the link.

  8. Click Review + create. After the validation is complete, click Create.

Schedule a contact with Aqua and save the downlinked data

Note

Check public satellite schedules to understand if there may be public broadcast outages. Azure Orbital Ground Station does not control the public satellites and cannot guarantee availability of data during the pass.

  1. In the Azure portal's search box, enter Spacecraft. Select Spacecraft in the search results.

  2. On the Spacecraft page, select your public spacecraft resource.

  3. Click Schedule contact on the top bar of the spacecraft's overview.

  4. On the Schedule contact page, specify the following information:

    Field Value
    Contact profile Select the contact profile you previously created.
    Ground station Select Microsoft_Quincy.
    Start time Identify a start time for the contact availability window.
    End time Identify an end time for the contact availability window.

  5. Click Search to view available contact times.

  6. Select one or more contact windows, and then click Schedule.

  7. View the scheduled contact by selecting the spacecraft resource, navigating to Configurations on the left panel, and clicking Contacts.

  8. Shortly before you start running the contact, start listening on port 56001 and output the data received in the file:

    Note

    This command references Aqua. Edit the command to reflect the public spacecraft you're using. In addition, you may need to add sudo.

    socat -u tcp-listen:56001,fork create:/media/aqua/out.bin

  9. After you run your contact, copy the output file from tmpfs into your home directory, to avoid overwriting the file when you run another contact:

    Note

    This command references Aqua. Edit the command to reflect the public spacecraft you're using.

    mkdir ~/aquadata
cp /media/aqua/out.bin ~/aquadata/raw-$(date +"%FT%H%M%z").bin

Note

For a 10-minute contact with Aqua while it's transmitting with 15 MHz of bandwidth, you should expect to receive around 450 MB of data.

Next steps