Other data applications
Other data applications
Pictures and Facsimiles — Many operators of police, fire and EMS systems have long dreamed to be able to send still pictures to and from mobile units in the field. The original version of this technology was called Slow Scan video, which took 10 to 300 seconds to send a complete picture across a radio circuit. As technology improved, high-resolution pictures could be transmitted in shorter periods of time — in fact, the process is almost instantaneous with modern 3G and 4G networks that are being used to complement traditional LMR systems.
Video — As more bandwidth became available, vendors developed solutions that transmit real-time video via radio from one location to another location. In addition, video-compression protocols evolved that reduced the bandwidth required for live video feeds.
Today, transmitting video feeds from fixed and mobile radios are considered the "killer app" for broadband applications. With public safety in mind, users can send streaming video of incidents, so officials away from the scene have the information they need to properly plan and participate. The new FirstNet deployment is expected to enable many types of video-feed applications to enhance situational awareness, including the streaming of video to and from users traveling at speeds up to 100 mph.
High-Speed Internet — When Internet access is available to mobile and portable radio users, the type and amount of data that can be accessed is unlimited. Fire departments can store bulky floor plans in a central computer, police department field units instantly can access criminal records. Meanwhile, air-conditioning mechanics can have every service manual for every make and model ever made at their disposal while on a service call in the attic of a house, and archeologists can have strata data available on-site at an excavation to confirm details of the dig. The advent of smaller, faster and lower-power computers makes all of this possible.
Smartphones that fit in a shirt pocket have full Internet capability, impressive displays and batteries that typically last an entire day on a single charge. In addition, these devices run applications that allow them to be used as sensors for monitoring the health of the user, as navigation tools, as cameras that take still or motion pictures, or for any of a million other potential uses.
Bandwidth and Carriers — As more data is carried on a radio channel, the bandwidth of that channel is required to be higher. In the past, when a radio was limited to 25 kHz of bandwidth, it was a challenge to achieve a throughput rate of 1,200 baud. However, with today's DSP chips and data-compression protocols, a 9,600-baud data rate can be realized easily in a 6.25 KHz channel. While the original cellular radio channels only could handle limited analog voice and short messages, today's broadband technology allows for full video and many megabytes of data to be sent over the channels to hundreds of smartphones simultaneously from a given site.
Costs — In the 1970s, landline-based modems were selling for one dollar per baud — a 300-baud modem was $300, a 1200-baud modem was $1,200, and so on. Radio modems were two to five times that cost. As the technology improved, the costs decreased and data throughputs increased. In addition, the size of the devices went from that of a large college textbook to as small as a user would want, because today's chips can be as small as 1/10th of a postage stamp.
Mobile and portable radios on the market today can transmit voice and data, and they are priced at less than 25% of the cost for voice-only radios a decade ago.
Availability in Emergencies — As people become attached to the functionality of feature-rich smartphones, many are abandoning landlines as a means of staying in touch with their families and friends. When a tornado, hurricane, earthquake, or terrorist attack occurs, commercial wireless networks become extremely busy and cannot sustain that kind of traffic load without serious degradation, especially if network infrastructure has been destroyed.
As public safety and other governmental entities have moved to the latest technologies for the services that they use as part of their normal operations, they cannot operate efficiently without these same systems being in place during emergencies. For this reason, it is essential that public safety's fledgling nationwide broadband network, which will leverage commercial technology, is hardened to withstand events that would shut down typical commercial systems.
Conclusion — As radio systems have evolved, the systems have become more useful and feature-rich, while devices have become smaller and costs have decreased dramatically. These new systems are more efficient, and they support non-voice communications just as much as they do voice traffic — perhaps more. The evidence is everywhere — just ask any teenager how they communicate with their friends, or look in the audience at a meeting or lecture, because it is easy to spot people reading or typing on their smartphones.
Ira Wiesenfeld, P.E., has been involved with commercial radio systems since 1966, and has experience with land-mobile-radio, broadcast, paging and military communications systems. He holds an FCC general radiotelephone operator's license, Extra Class amateur license, and is the author of Wiring for Wireless Sites, as well as many articles in various magazines. Wiesenfeld can be reached at [email protected].
Robert C. Shapiro, P.E., is a consulting engineer who has been in land mobile radio engineering — including public-safety and transportation communications — since 1984. He serves on the TIA TR8 committee (TSB-88) as vice chair and is a senior member of the IEEE. He can be reached at [email protected].
