Calculator Form
Example Data Table
| Parameter | Sample Value |
|---|---|
| Orbit Type | GEO |
| Altitude | 35,786 km |
| Elevation Angle | 35° |
| Range Mode | Automatic |
| Calculated Slant Range | 38,178.47 km |
| Space Legs | 2 |
| Total Propagation Delay | 254.78 ms |
| Terminal + Payload + Gateway | 16.00 ms |
| Backhaul + Queue + Coding + Packetization | 36.00 ms |
| One-Way Total | 306.78 ms |
| Estimated RTT | 613.55 ms |
| Bandwidth-Delay Product at 50 Mbps | 30.68 Mbit |
Formula Used
This calculator combines geometric propagation delay with practical network delays.
1) Slant range:
d = -R × sin(e) + √((R + h)² - (R × cos(e))²)
2) Propagation speed:
v = c / n
3) Propagation delay per space leg:
t_leg = (d / v) × 1000
4) Total propagation delay:
t_prop_total = t_leg × space_legs
5) One-way latency:
t_one_way = t_prop_total + terminal + payload + gateway + backhaul + queueing + coding + packetization
6) Round-trip latency:
RTT = t_one_way + (t_one_way × return_path_multiplier)
7) Bandwidth-delay product:
BDP(Mbit) = application_rate_mbps × (RTT / 1000)
Here, R is Earth radius, h is altitude, e is elevation angle, c is light speed, and n is refractive index.
How to Use This Calculator
- Select the orbit type or choose Custom.
- Enter the altitude and elevation angle.
- Pick automatic or custom slant range mode.
- Set the number of space legs in the path.
- Enter processing, payload, gateway, and backhaul delays.
- Add queueing, coding, and packetization delays.
- Use a return-path multiplier for asymmetric designs.
- Optionally enter application rate to estimate bandwidth-delay product.
- Press Calculate Latency to show the results above the form.
- Use the CSV or PDF buttons to export the result summary.
FAQs
1. What is slant range in a satellite link?
Slant range is the direct line-of-sight distance between the ground station and the satellite. It is longer than altitude unless the satellite is exactly overhead.
2. Why is GEO usually slower than LEO?
GEO satellites orbit much farther from Earth. That longer path increases propagation delay, so one-way and round-trip latency are usually much higher than LEO systems.
3. What do space legs mean?
A space leg is one ground-to-satellite or satellite-to-ground distance segment. A normal bent-pipe pass from user terminal to gateway typically uses two legs.
4. Does lower elevation angle increase delay?
Yes. Lower elevation means the satellite is viewed closer to the horizon, which increases slant range and therefore raises propagation latency.
5. Should I include terrestrial backhaul delay?
Yes. Real services often include fiber or routed transport between gateway sites, internet exchanges, or data centers. Ignoring backhaul can understate practical latency.
6. Is this calculator useful for gaming analysis?
It helps estimate transport latency, but gaming quality also depends on jitter, packet loss, server distance, NAT behavior, and application sensitivity to variable delay.
7. Can packetization and coding matter a lot?
Yes. On some services, FEC, interleaving, framing, and codec buffering add meaningful delay. They can noticeably change user experience, especially on voice and interactive traffic.
8. Why use a return-path multiplier?
Some networks are asymmetric. The forward and return paths may differ in routing, buffering, or access design. The multiplier approximates that imbalance without duplicating every field.