Satellite radio the next communications revolution
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Satellite Radio: The Next Communications Revolution?. David Bultman. Challenges In Satellite Radio. There are three general problems with satellite reception: Blockages Foliage Multipath Fading. Blockages. The target of satellite radio is a mobile platform

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Satellite Radio: The Next Communications Revolution?

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Satellite radio the next communications revolution

Satellite Radio: The Next Communications Revolution?

David Bultman


Challenges in satellite radio

Challenges In Satellite Radio

There are three general problems with

satellite reception:

  • Blockages

  • Foliage

  • Multipath Fading


Blockages

Blockages

The target of satellite radio is a mobile platform

  • This rules out the use of special high gain antennas and expensive satellite tracking systems

  • The important factors to think about when considering blockages are the movement of the receiver, the movement of the satellite, and the angle of elevation of the satellite


Foliage

Foliage

Foliage is similar to a blockage with a few

exceptions

  • Foliage can block or attenuate a signal

  • The amount of attenuation can depend on the type of foliage, the frequency of the signal, and the incident angle

  • Foliage can also reflect a signal with a random amount of attenuation and phase shift


Multipath fading

Multipath Fading

  • Multipath Fading occurs multiple forms of the original signal are received


Solutions spatial diversity

Solutions – Spatial Diversity

Spatial Diversity = Instead of having a single signal source, use multiple signal sources spread out

  • Spatial Diversity helps fix all three of the problems


Solutions frequency diversity

Solutions – Frequency Diversity

Frequency Diversity = Sending the same information on two separate and unrelated frequencies (preferably also spatially diverse)

  • Frequency Diversity is aimed at fixing multipath fading


Solutions time diversity

Solutions – Time Diversity

Time Diversity = Delaying one of two spatially diverse signals in time before its broadcast

  • Time Diversity is aimed at eliminating audio outages when both broadcast signals are blocked simultaneously


Solutions repeater stations

Solutions – Repeater Stations

Repeater Stations are used in areas where even the combination of the other three solutions may not yield a “good” signal


Xm radio s system

XM Radio’s System

  • Two geostationary satellites with a 45 degree angle of elevation

  • Each satellite emits about 10MW of signal energy

  • Approximately 1500 low power repeater stations serving 70 markets


Sirius radio s system

Sirius Radio’s System

  • Three satellites in an inclined elliptical orbit

  • Each satellite spends about 16 hours over the US, with two satellites always above the equator


Sirius radio s system1

Sirius Radio’s System

  • The satellites are inclined at 60 degrees

  • The satellites are of lower power than XM Radio’s

  • 105 high power repeaters serving 46 markets


The future

The Future?

  • From all indications the audio quality is superb with both providers

  • The tests will be subscriber numbers and the possibility of terrestrial radio adding digital signals to their broadcasts to compete


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