Translate a satellite mission’s daily data production into a required downlink rate. Enter data volume, total contact time, usable contact fraction, protocol overhead, and design margin. The result separates payload throughput from transmitted throughput and helps define a communications requirement that can be carried into link-budget and ground-station trade studies.
The required link rate is the physical transmitted rate needed during usable contacts to return the stated daily payload volume, including overhead and margin.
This calculator uses decimal units: 1 GB = 10⁹ bytes and 1 Mbps = 10⁶ bits/s. Model compression by reducing the payload data input.
For 500 GB/day, 40 minutes of contact, 80% usable time, 15% overhead, and 20% margin, usable contact is 32 minutes and the required link rate is about 2,941.18 Mbps.
Enter the volume that must actually be delivered after any compression you are confident the mission can achieve.
A lower usable fraction shortens effective downlink time, so the same daily data requires a higher instantaneous rate.
It can include framing, headers, coding expansion, synchronization, and other transmitted bits that do not carry payload.
It uses decimal units: one gigabyte equals one billion bytes.
No. This is a data-rate requirement; use it to select a waveform and receiver threshold for a separate link budget.
| Input | Unit | Role |
|---|---|---|
| Payload data per day | GB | Uncompressed or mission-planned payload volume. |
| Scheduled contact time | min/day | Total nominal downlink opportunity. |
| Usable contact fraction | % | Fraction remaining after acquisition and outages. |
| Protocol overhead | % | Share of transmitted bits not carrying payload. |
| Rate design margin | % | Capacity allowance above calculated throughput. |