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Home > EMS Products > Communications
October 18, 2011
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EMS News in Focus
by Arthur Hsieh

How EMS communication has changed in the digital age

As the newest wireless technology rolls out, it's a good time to take look at what has been, where we are today, and what might coming down the pike for tomorrow

By Arthur Hsieh

A century from now, historians will look back at the late 1900s and early 2000s as the digital information age.

Over the past few decades, society has shifted from antiquated ways of receiving, sending and analyzing information – such as newspapers, books, facsimiles, and telephones – to the use of more sophisticated technology that transformed the printed and spoken word into digital bits and bytes of data, bundle it with video and sound signals, and sent it to devices that not only could reproduce it precisely, but also integrate multiple data streams into a understandable, more complete picture.

As the newest wireless technology rolls out, it's a good time to take look at what has been, where we are today, and what might coming down the pike for tomorrow.

From the Simplex to the Complex
When modern EMS began in the early 1970s, base stations and mobile units were still relying on what was essentially mid-century technology to transmit information.

With this "can and string" technology, sound was converted to an analog signal, which was then transmitted by radio that used very high frequency (VHF) waves. These systems were very simple – "simplex" – and required that the sender and receiver transmit only one at a time, over the same frequency, in order to be heard. This technology developed into a "duplex" format – which used two frequencies – to allow the sender and receiver to hear and talk to each other simultaneously, similar to a telephone.

Most early advanced life support systems needed a way to transmit ECG telemetry to the base or receiving hospital as the ALS provider was providing care. Ultra High Frequency (UHF) channels were designated for use by EMS for this purpose, along with voice transmission of the paramedic and physician.

"Multiplex" technology allowed the simultaneous transmission of telemetry and voice signals. These "med channels" are still widely used today in EMS systems across the United States.

From analog to digital
Until relatively recently, all of this communication technology relied on analog signals to carry information.

Analog can be affected by a variety of environmental factors, and required significant power to be transmitted. Moreover, analog was highly limited in what types of data could be carried.

The first wireless telephones of the early 1980s used analog signaling. Things began to change with the first generation, or 1G, digital devices began an era where the use of multiple antenna sites – cells – scattered throughout the area allowed much lower-powered devices to be used by the consumer.

When the personal computer took off, so did wireless technology. 2G networks rapidly replaced 1G in the late 80s and early 1990s. Using the common language of data bits and bytes, organizations found that they could send not only voice and other analog signals digitally, they could do so simultaneously and at lower power requirements.

More information could be sent because digital data was organized into "packets" that could be sent over very brief periods of time, freeing up more of the radio band to send even more data. As 2G transitioned into 3G, these packets became increasingly efficient, allowing for even greater data transmission rates.

Where we are today
Many EMS systems today are already using 3G technology. Voice-based dispatch communications are replaced by mobile data terminals (MDT) that display key information about scene locations and conditions over portable computers, smartphones and tablets.

Paper patient care reports are slowly being replaced by ePCRs, which can send completed charts to patient's records at their hospital. A few systems can transmit visual information about patients, along with ECGs, vital signs and other measurements from the field unit to a base station for physician consult. Even operational data about the working condition of the ambulance can be transmitted, allowing for more precise preventive maintenance to take place.

What tomorrow might bring
Fourth generation wireless technology will undoubtedly usher in the era of broadband communications. 4G sends information 10 to 100 times faster than existing 3G technology. This rate rivals and even exceeds the data transmission rate of existing "wired" technology such as digital subscriber lines (DSL).

The increasing capacity that will come from broadband will open additional communication opportunities. For example, personnel utilizing broadband tablets on the scene of multiple casualty events could record, track and analyze the dozens (or even hundreds) of patients to multiple hospitals, something that is very difficult to do using paper and pencil MCI tracking forms.

Multiple streams of data from ECG monitors, ePCRs, and other patient monitoring equipment could allow real time analysis of crew performance by off scene personnel during a critical medical event, without the on-scene crew having to spend time setting up communication equipment.

The data could flow in the other direction too – imagine getting a synopsis of your patient's medical history and medication list sent to your tablet from a hospital database, while you are talking with the patient? This could be a terrific tool for community or advanced-practice paramedics to use when evaluating patients for referral or on-scene primary care.

Summary
We live in a world where information is power. The ability to move that information around quickly and intelligently will allow EMS systems to consider the communication with both internal and external resources in ways we could not have thought about a mere 20 years ago. It will be interesting to see what the next twenty years of broadband development will bring.

About the author

EMS1 Editor in Chief Art Hsieh, MA, NREMT-P currently teaches at the Public Safety Training Center, Santa Rosa Junior College in the Emergency Care Program. In the profession since 1982, Art has worked as a line medic and chief officer in the private, third service and fire-based EMS. He has directed both primary and EMS continuing education programs. Art is a published textbook author, has presented at conferences nationwide, and continues to provide patient care at a rural hospital-based ALS system. Contact Art at Art.Hsieh@ems1.com.
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