How is Sirius XM radio different than AM/FM.. I know AM is radio transmissions created by changing the power of the carrier wave, and FM are transmissions created by changing the speed at which radio waves are generated.
You have a great misunderstanding.
AM: the amplitude of the carrier wave is modified slightly, average power does not vary much.
FM: The carrier frequency is lightly modified by the information, amplitude largely remains the same.
Now both of those signals have a magnetic and electric field that are 90 degrees to each other. Normally, AM radio uses vertical polarization (notice how car antennas go upwards). FM radio is largely in the US Horizontal polarization, as are tV stations.
Nowadays, FM stations in cities usually transmit "mixed" polarizations, which have components horizontal and vertical, these can penetrate buildings easier.
Now XM "satellite" radio is quite another system. Two satellites, transmitting on six channels, half of it duplicated for redundancy, and a large number of land repeaters (about 900). A typical city has about 20 land stations. The information received by a receiver is digital, and has to be decoded. To ensure signal reliability, two signals of three channels each reach the receiver, and are digitally processed. At the signals are a commbination of land, and or satellite digital signals, the user cannot know easily. The modulation used is a common type, phase shift keying, used in digital communciations. The polarization from the satellite is circular, from the land stations, mixed.
Sirius XM radio is different from AM/FM radio in several ways. While AM (Amplitude Modulation) and FM (Frequency Modulation) radio use terrestrial (land-based) transmission towers to broadcast radio signals, Sirius XM radio relies on satellite technology for its transmission.
Here's a breakdown of the key differences:
1. Transmission method: Traditional AM/FM radio stations transmit their signals by modulating the carrier wave's amplitude (AM) or frequency (FM) using terrestrial antennas. In contrast, Sirius XM radio broadcasts its signals from satellites in space, which then transmit the signals to special antennas on the ground, such as satellite radio receivers in vehicles.
2. Signal coverage and availability: AM/FM radio signals are limited by the range of their terrestrial transmission towers, typically spanning a few miles. Sirius XM, however, provides nationwide coverage throughout the United States and parts of Canada through its network of satellites, enabling uninterrupted broadcasting across large distances. This makes Sirius XM particularly valuable for long-distance road trips or in areas with limited AM/FM station availability.
3. Content and programming: One of the notable distinctions is the content offered. While AM/FM stations vary in terms of music, talk shows, news, and local programming, Sirius XM radio provides a wider range of specialized content. It offers a vast selection of commercial-free music channels covering various genres, exclusive talk shows, sports broadcasts, news, and other entertainment options. This means subscribers to Sirius XM can enjoy a diverse range of content options catering to their specific interests.
4. Subscription-based service: Unlike traditional AM/FM radio, which is generally free to listen to, Sirius XM is a subscription-based service. To access Sirius XM's vast array of channels and content, users must pay a monthly or yearly fee. This subscription model helps support the costs of operating the satellite infrastructure and delivering high-quality programming.
In summary, the key differences between Sirius XM and AM/FM radio stem from their transmission methods, signal coverage, content offerings, and pricing models. Understanding these distinctions helps explain the unique features of each radio platform.