Some Brief Descriptions of Various Radio Systems

reference to mostly to industrial, business, public safety, consumers

Frequency Division Multiple Access (FDMA)
Original cellular channels were 30 KHz wide and accommodated one voice signal subscriber.

Time Division Multiple Access (TDMA)
Increased the number of users by 3:1 by allowing each subscriber to talk for a few milliseconds in rotation, three conversations now take place within the same 30 KHz channel.

Code Division Multiple Access (CDMA)
Spread spectrum techniques Frequency Hopping and Direct Sequence. Both systems use vocoders (voice coder/decoder) to digitize the signal.

Location and Monitoring Service (LMS)
LMS systems utilize non-voice radio techniques to determine the location and status of mobile radio units (902-928 MHz).

Interactive Video and Data Service (IVDS)
An IVDS system is a point-to-multipoint, multipoint-to-point, short distance communications service for its licensees to provide information, products, or services to, and allow interactive responses from, subscribers in the licensee's service area.

Trunked Radio System (TRS)
A trunked radio system differs from a conventional system in its ability to automatically search two or more available channels and assign a user an open channel. In a conventional radio system, a radio can access only one channel at a time.

Personal Radio Services (PRS)
Short-range, low power radio for personal communications, radio signaling, and business communications not provided for in other services.

Back to home page