How LA-RICS improves public safety

The Land Mobile Radio (LMR) system allows first and second responders to communicate directly with one another on a day-to-day basis, replacing a patchwork of 40+ aging radio networks as LA County’s primary means of public safety communications.

The system provides increased coverage and capacity, and eliminates barriers to multi-jurisdictional responses by allowing police, firefighters and paramedics in the field to communicate directly with users outside of their agency.

 

Why install a radio site in my area?

Each site provides a unique coverage footprint, ensuring that first and second responders always have the ability to communicate with each other in your area, for faster protection and improved safety. It is anticipated that State and Federal agencies operating within the Los Angeles region will utilize LA-RICS for mutual aid communications.

 

The role of light in Telecommunication Technology

Visible light, like radio, is a form of electromagnetic (EM) energy capable of transmitting information within a communication system. High-speed data, for example, can be transmitted through an optical fiber cable cable by passing pulses of [visible] light through fine stands of glass contained within the cable.

EM energy can be transmitted outside of a material medium and through space when physical connections are neither practical nor feasible. For a simplified representation of how information can be shared across space, consider two ships in the night, each with a flashlight, transmitting messages using a series of patterns—in a similar fashion to morse code.

Such a system would be ineffective in daylight, or in the presence of any external light sources potentially interfering with the receiver’s ability to interpret each set of patterns clearly.

Conversely, radio frequency (RF) transmissions are far less impacted by the environment, allowing signals to travel across great distances with less degradation.

 

What are radio waves?

Applying energy to an atom causes its electrons to “jiggle” (i.e. oscillate) and emit waves of energy. The frequency of this oscillation determines the type of wave that is produced.

Radio waves carry less energy than visible light waves. They are essentially a form of light, but with a much lower frequency.

 

Is RF Energy Safe?

Scores of scientific studies have researched the correlation between RF exposure and long-term health effects, finding no conclusive evidence that RF exposure contributes to the likelihood of diseases nor birth defects.

Unlike x-rays and gamma rays (extremely high frequency), radio waves (low frequency) and visible light (medium/high frequency) do not carry enough energy to damage DNA molecules!

Radio waves carry relatively low energy, typically passing through objects as a result of their inability to interact with them on an atomic level. Conversely, visible light is easily reflected and absorbed, illuminating an object and heating its surface.

 

Maximum Permissible Exposure (MPE) Limits

MPE limits are defined to limit human exposure to RF energy fields. The FCC MPE occupational limit includes a safety margin, protecting workers with the potential for close proximity to radio transmitters. The MPE limit for general population exposure is far more stringent, as depicted in the graph below.

In compliance with the FCC, RF Emissions Reports are conducted by experts in Radio Frequency Safety Regulations to verify that power levels do not exceed applicable MPE limits, even when transmitting at full power.

Much like visible light, the energy carried by radio transmissions disperses very quickly, causing power to be concentrated only at the source.

 

 

Because of this, common household devices expose the general public to higher levels of RF than antennas installed on a tower. (See Graph Below) 

 

Radio Frequency (RF) Emissions Modeling

Even when transmitting at full power—as in the case of a wide-scale emergency—RF exposure caused by LA-RICS antennas remains significantly lower than exposure levels resulting from cell phones, laptop computers and microwave ovens.

Example at Rolling Hills Transmit (RHT) Communications Site:

The chart below depicts RF exposure levels experienced by the general public on a day-to-day basis.

The grey limit line represents general population MPE limits set by the FCC, for frequencies within the 30 MHz and 800 MHz range. The line is marked to show where MPE limits exist at various LA-RICS frequency bands.

The columns represent modeled human exposure levels resulting from common household devices relative to LA-RICS RHT installation.

MAX at RHT assumes you are standing within 50 feet of the tower, when antennas are transmitting at full power during the case of an emergency.