How to configure the RF chain

You have the flexibility to choose between managed modem or virtual RF functionality using the Azure Orbital Ground Station service. These operational modes are specified on a per-channel basis in the contact profile. See ground station contact profile to learn more about channels and links.

Prerequisites

• Managed modem: a modem configuration file
• Virtual RF: GNU radio or software radio

Managed modems vs virtual RF delivery

We recommend taking advantage of Azure Orbital Ground Station's managed modem functionality, if possible. The modem is managed by the service and is inserted between your endpoint and the incoming or outgoing virtual RF stream for each pass. You must provide a modem configuration file in XML format to specify the modem setup. Currently, we use Kratos quantumRX v1.4 and Kratos quantumRadio v4.0 modems. Your modems and modem configurations must match these versions. You can also apply one of the in-built named modem configurations for commonly used public satellites such as Aqua.

Virtual RF delivery can be used if you wish to have tighter control on the modem setup or bring your own modem to the Azure resource group. Azure Orbital Ground Station will connect to your channel endpoint that is specified in the contact profile.

How to configure your channels

The table below shows you how to configure the modem or virtual RF parameters.

Parameter	Options
modulationConfiguration	1. Null/empty for virtual RF 2. Modem config for software modem 3. Named modem string
demodulationConfiguration	1. Null/empty for virtual RF 2. Modem config for software modem 3. Named modem string
encodingConfiguration	Null (not used)
decodingConfiguration	Null (not used)

Note

The endpoint specified for the channel will apply to whichever option is selected. Please review how to prepare network for more details on setting up endpoints.

Full-duplex cases

Use the same modem configuration file in uplink and downlink channels for full-duplex communications in the same band.

How to input the modem config

You can enter your existing modem configuration when creating a contact profile object or add it in later. Modifications to existing modem configurations are also allowed.

Entering the modem configuration

Using the Azure Orbital Ground Station API

Enter the modem configuration as a JSON escaped string from the desired modem configuration file when using the Azure Orbital Ground Station API.

Using the Azure Portal

Select 'Raw XML' and then paste the modem configuration raw (without JSON escapement) into the field shown below when entering channel details using the Azure portal.

Named modem configuration

We currently support the following named modem configurations:

Public Satellite Service	Named modem string	Note
Aqua Direct Broadcast	aqua_direct_broadcast	NASA Aqua main signal - 15 Mbps direct broadcast service
Aqua Direct Playback	aqua_direct_playback	NASA Aqua alternative signal - 150 Mbps direct broadcast service
Terra Direct Broadcast	terra_direct_broadcast	NASA Terra - 13.125 Mbps direct broadcast service
SNPP Direct Broadcast	snpp_direct_broadcast	NASA Suomi-NPP (SNPP) - 15 Mbps direct broadcast service
JPSS-1 Direct Broadcast	jpss-1_direct_broadcast	NASA JPSS-1 - 15 Mbps direct broadcast service

Note

We recommend using the Aqua Direct Broadcast modem configuration when testing with Aqua.

Azure Orbital Ground Station does not have control over the downlink schedules for these public satellites. NASA conducts their own operations which may interrupt downlink availabilities.

Spacecraft Title	noradID	centerFrequencyMhz	bandwidthMhz	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

Specifying a named modem configuration

Using the Azure Orbital Ground Station API

Enter the named modem string into the demodulationConfiguration parameter when using the Azure Orbital Ground Station API.

{
    "location": "westus2",
    "tags": null,
    "id": "/subscriptions/c098d0b9-106a-472d-83d7-eb2421cfcfc2/resourcegroups/Demo/providers/Microsoft.Orbital/contactProfiles/Aqua-directbroadcast",
    "name": "Aqua-directbroadcast",
    "type": "Microsoft.Orbital/contactProfiles",
    "properties": {
        "minimumViableContactDuration": "PT1M",
        "minimumElevationDegrees": 5,
        "autoTrackingConfiguration": "disabled",
        "eventHubUri": "/subscriptions/c098d0b9-106a-472d-83d7-eb2421cfcfc2/resourceGroups/Demo/providers/Microsoft.EventHub/namespaces/demo-orbital-eventhub/eventhubs/antenna-metrics-stream",
        "links": [
            {
                "polarization": "RHCP",
                "direction": "Downlink",
                "gainOverTemperature": 0,
                "eirpdBW": 0,
                "channels": [
                    {
                        "centerFrequencyMHz": 8160,
                        "bandwidthMHz": 15,
                        "endPoint": {
                            "ipAddress": "10.6.0.4",
                            "endPointName": "my-endpoint",
                            "port": "50001",
                            "protocol": "TCP"
                        },
                        "modulationConfiguration": null,
                        "demodulationConfiguration": "aqua_direct_broadcast",
                        "encodingConfiguration": null,
                        "decodingConfiguration": null
                    }
                ]
            }
        ]
    }
}

Using the Azure Portal

Select 'Preset Named Modem Configuration'and chose a configuration as shown below when entering channel details using the Azure portal.

How to use virtual RF

To use the virtual RF delivery feature, leave the modulationConfiguration or demodulationConfiguration parameters blank in the channel parameters. Azure Orbital Ground Station uses the Digital Intermediate Frequency Interoperability or DIFI format for transport of virtual RF. Refer to the virtual RF tutorial to learn more.

Note

For downlink, Azure Orbital Ground Station will provide an RF stream in accordance with the channel bandwidth setting to the endpoint.

For uplink, Azure Orbital Ground Station expects an RF stream in accordance with the channel bandwidth setting from the endpoint.

Next steps

• Register Spacecraft
• Prepare the network
• Schedule a contact