Best use of a regional satellite is not for telecom but for digital broadcasting

Posted on September 10, 2015  /  1 Comments

Bangladesh keeps talking about launching a satellite. Sri Lanka threw some money at it, but backed off. Myanmar is talking. Now India wants to gift SAARC member countries with a satellite to be launched using ISRO’s innovative, low-cost launch capabilities. Something Keynes wrote about economics gave me the answer to the puzzle of why our region’s decision makers are so enamored with telecom satellites. Using satellites for international backhaul was a veritable technological revolution back when these people (and I) were at an impressionable age. But the world has moved on, and running data traffic through geostationary satellites is now obsolete. We now need to look at what geostationary satellites are best at, or focus on LEO/MEO satellite systems.

In the 1960s, the highest-profile use was for telecommunication, where massive antenna connected to a single satellite provided a qualitatively superior solution for international backhaul over the extant methods of copper cables wrapped in gutta-percha or radio waves that bounced off the ionosphere. Here, the satellite appeared stationary relative to earth because it was in the Clarke or geostationary orbit. That technological revolution of their youth appears have been deeply imprinted in the minds of today’s decision makers.

But this particular use is now obsolete. The cause is physics. Geosynchronous satellites are located 35,786 km above sea level. It takes more than 500 milliseconds (or more than half a second) for a signal to complete the full hop (up to the satellite and then down), resulting in high latency, or delay. Latencies greater than 300 ms are unacceptable for most present-day communication applications. Satellite transmission now fails to meet user expectations and system parameters which have been shaped by the short latencies made possible by fibre-optic cables.

Satellites are still used for telecommunication in regions with low population densities, including isolated islands with small populations, such as those in the Pacific. These satellites are placed in low-earth or medium-earth orbits (LEO/MEO satellites) to keep latencies at acceptable levels. However, this requires complex hand-offs between satellites, because LEO/MEO satellites are not stationary relative to earth.

The amount of data they can carry is less than what fibre-optic cables can. Thus, they are rarely competitive with fibre backhaul in densely populated regions such as South Asia, perhaps with the exception of Bhutan and remote and thinly populated northern parts of India, Nepal and Pakistan. They may also be useful in Afghanistan due to security problems, but plenty of terrestrial cables were laid in that country in the past decade.

– See more at:–Looking-a-gift-horse-in-the-mouth?#sthash.mS7ImOv5.dpuf

1 Comment

  1. The article has been carried on p. 4 of Financial Daily in Pakistan: