Wireless Ch 3 cont

Signal Strength cont.

 

Directional Antenna is used to minimize multipath distortion and radiates electromagnetic waves in one direction only.

There are other methods to reduce multipath distortion; using an amplifier in front of receiver to increase SNR and transmitting the same signal on separate frequencies.

Advantages and Disadvantages of the Standards:

Advantages are: guaranteed device interoperability, creates competition which results in lower costs and greater improvements, and it helps consumers protect their investment in the equipment.

The disadvantages are: it can be a threat to industries in large countries and although standards are intended to create unity they can have the opposite effect. 

Types of standards:

De Facto are not really standards at all, but common practices that the industry follows.

De Jure are also called official standards.  They are controlled by an organization or body and the process for creating standards can be very involved.

Consortia is an industry-sponsored organizations that promote a specific technology. 

Telecommunications Standards Organizations

US groups

-American National Standards Institute (ANSI)

-Electronic Industries Alliance (EIA)

-Telecommunications Industries Association (TIA)

-Internet Engineering Task Force (IETF)

-Internet Architecture Board (IAB)

-Internet Society (ISOC)

-Institute of Electrical and Electronics Engineers (IEEE)

Multinational Standards Groups

-European Telecommunications Standards Institute (ETSI)

International Standards Groups

-International Telecommunications Union (ITU)

-International Organization for Standardization (ISO)

Regulatory Agencies

Enforcing telecommunications regulations is important.  Regulations must be enforced by an outside agency, and the agency here is the Federal Communications Commission (FCC)

Radio Frequency Spectrum

The radio frequency spectrum is the entire range of all radio frequencies that exist.  The range extends from 10KHz to over 30GHz and the spectrum is divided into 50 different sections (bands).

Radio frequencies of other common devices include:

-garage door openers, alarm systems: 40MHz