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Satellite Link Mission Requirements Estimator

The Satellite Link Mission Requirements Estimator translates a planned data volume and contact schedule into the average net throughput each satellite pass must deliver. It accounts for the number of contacts, usable duration per contact, and a link-efficiency factor that represents framing, coding, protocol, or operational overhead.

This is an early mission-sizing tool for checking whether a communication concept can move the required amount of data within the available contact windows. The result is a required raw link rate under the entered efficiency assumption. It does not determine RF feasibility by itself; use a signal budget to verify that the chosen modulation and data rate can be supported at the expected range and antenna geometry.

Inputs

GB
min
%
Result
—
Required raw link rate
Total contact time—
Required net throughput—
Efficiency assumption—

1. Enter the data volume
Use the amount of user data that must be transferred during the planning cycle.

2. Enter contact count
Use the number of usable satellite-ground contacts in that cycle.

3. Set usable contact duration
Enter average minutes available for actual data transfer during each contact.

4. Set net efficiency
Represent protocol, coding, framing, and operational overhead as the fraction of raw link capacity that becomes useful payload throughput.

5. Review required rate
Use the raw Mbps result as a target for modem and link-budget evaluation.

Total contact time = Contacts × Minutes/contact × 60 Required net throughput = Data bits / Total contact time Required raw rate = Net throughput / (Efficiency / 100)

The calculator uses decimal gigabytes: 1 GB = 10⁹ bytes, and 1 byte = 8 bits.

What the result means

The main result is the raw link rate needed to deliver the entered data volume within the available contacts after accounting for efficiency.

Contact duration should be the usable data-transfer interval, not the full geometric pass if acquisition, handover, or low-elevation periods are excluded.

Given: 120 GB per cycle, 6 contacts, 12 usable minutes per contact, and 75% efficiency.

Calculation: Total contact time = 6 × 12 × 60 = 4,320 s. Net throughput = 960×10⁹ / 4,320 ≈ 222.22 Mbps. Raw rate = 222.22 / 0.75 ≈ 296.30 Mbps.

Result: The link should support roughly 296.3 Mbps raw rate under these assumptions.

What is a planning cycle?

Use any consistent period—such as one orbit, one day, or one downlink campaign—as long as data volume and contact count refer to the same period.

Why use net link efficiency?

User data usually occupies less than 100% of the raw channel because coding, framing, protocol, retransmission, and operational overhead consume capacity.

Does this calculator include uplink traffic?

Only if you include uplink data in the entered volume. For asymmetric systems, it is usually clearer to size uplink and downlink separately.

Can a high required rate still be infeasible?

Yes. RF power, antenna gains, bandwidth, coding, regulatory limits, hardware capability, and link margin may constrain the achievable rate.

How is this different from the observation-time estimator?

This calculator solves for the data rate needed from a fixed contact schedule; the observation-time estimator solves for time needed when a data rate is already known.