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Understanding Radio Spectrum: VHF and 700/800 MHz

Learn the differences between VHF and 700/800 MHz radio spectrum, analog and digital signals, and conventional and trunked radio systems in plain language. Contact On Target Training & Consulting for more information.

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Understanding Radio Spectrum: VHF and 700/800 MHz

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  1. RADIO “In plain language” PRESENTED BY: On Target Training & Consulting, LLC Contact us: Ontarget.tc@msn.com 320-584-5416 1 Tomorrow's Solutions Today

  2. Learning Goal • Student ability to understand and explain basic differences between: • VHF and 700/800 MHz Radio spectrum • Analog and digital signal • Conventional and trunked radio systems 2 Tomorrow's Solutions Today

  3. Learning Objectives and Evaluation • Students will be able to explain, to the instructor’s satisfaction, the basic characteristics of VHF and 700/800 MHz radio spectrum. • Students will be able to explain, to the instructor’s satisfaction, the basic characteristics of analog and digital radio signals. • Students will be able to explain, to the instructor’s satisfaction, the basic differences between conventional and trunked radio systems. • Students will demonstrate knowledge and retention of training material through a testing process. 3 Tomorrow's Solutions Today

  4. Table of Contents • Radio Frequency • Analog vs. Digital • Narrow Banding • Conventional Systems • What is Trunking • Trunked Systems • 700/800 MHz 4 Tomorrow's Solutions Today

  5. Frequency Spectrum Radio Frequencies SHF • Individual frequencies are simply a piece of radio spectrum in the open airwaves. • The lower the frequency: • Typically the greater the travel distance. • More noisy and susceptible to interference. • Atmospheric • Skip • The higher the frequency: • Typically the shorter the travel distance. • Less impact by man-made interference. • Less impact by natural interference/noises. 800 MHz ARMER State Radio System 700 MHz Some Law Utilities Hospitals 450 MHz UHF Most Public Safety Radio 155 MHz VHF 95 MHz KS 95 830 KHz WCCO-AM HF 5 Tomorrow's Solutions Today

  6. Analog vs. Digital • Analog • Signals can be noisy and susceptible to interference atmospheric (white noise) skip man-made sources • Most radio systems were built on analog signal. Technology advances within the last 30 years or so have made significant advances into the digital signal world. Analog Signal Digital Signal 6 Tomorrow's Solutions Today

  7. Analog vs. Digital • Digital • Radios convert sounds to strings of “ones” and “zeros” (DATA) before transmitting and receiving. This allows transmissions to be made more clear. • Digital voice signals can be sent in a narrower span of radio spectrum. • More channels can be placed in the same range of frequencies. Analog Signal Digital Signal 7 Tomorrow's Solutions Today

  8. Analog vs. Digital • Digital • Digital signals allow for distance recapture. What that means is that as the signal (data) starts to break up because of distance traveled, the electronics of the radios and system are “smart enough” to restore some of the lost data. • This is done through receiving technology (Vocoder). • Typically, digital 700/800 frequencies penetrate buildings better because they have shorter wave lengths. Analog Signal Digital Signal 8 Tomorrow's Solutions Today

  9. What is Narrow Banding? Narrow Banding is the cutting in half of the radio spectrum channels to allow for the doubling of the number of frequency/channels available. For those that are “techy” again 9 Tomorrow's Solutions Today

  10. Who does Narrow Banding apply to? • The FCC has required all radios below 512 MHz to be narrow band compliant (frequency cut in half) by the end of 2012. • This affects all radio systems that operate on or below 512 MHz (affects VHF and UHF). • There is a possibility to have to do it all over again sometime after 2018. • Failure to narrow band could result in the loss of your radio privileges. 10 Tomorrow's Solutions Today

  11. Analog vs. Digital and Narrow banding Analog Signal • The “white noise” that is currently within the VHF radio spectrum does not know what narrow banding is. In other words, it will remain the same and take up as much of the frequency spectrum as it does now. • Digital systems have an easier time dealing with this “white noise” than analog systems do. Digital Signal VHF frequency before narrow banding VHF Frequency after narrow banding white noise white noise 11 Tomorrow's Solutions Today

  12. Conventional Systems vs. Trunked Systems Conventional Systems: • Use a dedicated radio frequency for each radio channel in a system. Repeater channels use 2 frequencies VFIRE 23 or VLAW31 vs. your main. • A frequency, i.e. 155.340 the statewide EMS channel, is a dedicated piece of radio spectrum. • Each frequency is assigned to an entity (license holder). • If a channel is in use, the radio user must wait for it to clear before being able to transmit. • If you want to add a channel, you must first obtain a new frequency or frequencies. 12 Tomorrow's Solutions Today

  13. Conventional Radio System • Conventional radio system users talk on their own channels (frequencies). Lets say an entity has the following: • A fire dept. with three (3) frequencies • A police dept. with two (2) frequencies • A public works with one (1) frequency • If more than two groups of people in public works want to talk at the same time, they must wait until the frequency is clear. • This is the case even if there is no radio traffic on any of the fire or police frequencies. • This is an inefficient use of frequencies. Fire Frequency Police Frequency Public Works Frequency 13 Tomorrow's Solutions Today

  14. Trunked Systems • Trunking is: • The sharing of a limited number of communication paths (trunks) among many users. • Think of a hospital or law enforcement facility and how their phone system works: A lot of calls on just a few phone lines. • Within the context of radio, several similar frequencies are used to create a ‘shared pool’ for radio system users to access. • Trunked systems can be built using VHF, UHF or 700/800 MHz 14 Tomorrow's Solutions Today

  15. Trunked Systems Cont. • Within Trunking Systems: • The system is managed by a computer known as the “central controller.” • All subscribers (radios) on the system are computer controlled by one frequency known as the “control channel,” which is routinely communicating with the subscribers (radios). • Former channel (frequency) changing is now a selection on your radio referred to as a “Talk Group.” • Talk group is simply a “virtual channel.” It is a computer generated code (data). 15 Tomorrow's Solutions Today

  16. A A C C A C B B B C A C A C A B B B Trunked System Remember, the controller is routinely communicating with all subscribers (radios) that are turned-on through the use of the control channel. Consider it to be the radios “just sitting idle.” When you press the push to talk (PTT), the controller, through the control channel, assigns an available frequency to the radios for communications. The controller does this and the user really never knows that it happened. ControlChannel Controller Available channels 16 Tomorrow's Solutions Today

  17. C A A C C C C C B B B B B B • When a user pushes the PTT: • The computer moves all radios, set to the same talkgroup, to the first available frequency. • This happens in micro seconds. • The user never really knows what frequency the radio is transmitting or receiving on. ControlChannel A PTT Channel assigned A A Available channels A 17 Tomorrow's Solutions Today

  18. C C A A C A B B B C A C A A C B B B Trunked System • When the user releases the PTT: • The system releases the frequency. • The radios again communicate with the controller via the control channel (back to “idle”). • Another user responding may be assigned a different frequency when they push the PTT. ControlChannel Controller Available channels 18 18 Tomorrow's Solutions Today

  19. C C C C C C A A B B B Trunked System • What this allows for: • Exponential utilization of frequencies. • More efficient use of frequencies system wide. • As you can see, one frequency or channel is still available. Illustrates all radios being assigned to frequencies ControlChannel B A A A A B Available channel B 19 Tomorrow's Solutions Today

  20. Trunked Radio Benefits • Improved usage of radio frequencies. • Users on a common radio system platform. • Greater system flexibility. • Interoperability • Trunked and simplex resources (point to point) • Additional advanced features on subscriber (radio) units. • Push to talk ID, alias list • Talkgroup reprogramming • Call alert • Radio inhibit • Emergency button 20 Tomorrow's Solutions Today

  21. Trunked Radio Benefits (CONT.) • Capacity expectations • Trunked resources • Large number of talkgroups allows for seamless interoperability. • Simplex resources (point to point) • Allows for on scene interoperability without utilizing system resources. • Like using the radio as a walkie-talkie. 21 Tomorrow's Solutions Today

  22. Trunked Radio Benefits (CONT.) • Clarity expectations: • Digital signal • You have it or you don’t. When you have it, it is really clear, practically speaking. When you lose it, it is gone. (Similar to your digital cell phone). • Situational management: • ICS principles • Better effectiveness, efficiency and safety at incidents through the assignment of separate talk groups by facet or job task. 22 Tomorrow's Solutions Today

  23. Trunked Radio Concerns • Statewide system • Not just your resources or radio system • We must change the way we think. The system may not work well if we all continue wanting to be our own island, or keep a silo philosophy. • Geography • Tower sites coverage not necessarily designed for in building portable coverage. • Roaming • Your entity’s main talkgroups if allowed to ‘work’ on all tower sites statewide can cause unnecessary geographic loading (use of radio frequencies). 23 Tomorrow's Solutions Today

  24. Trunked Radio Concerns • Capacity expectations • Trunked resources • Governance, policy and procedure • State, regional and local standards and protocols, if not developed, are needed and must be in place. • Simplex resources • Governance, policy and procedures • State, regional and local standards and protocols, if not developed, are needed and must be in place. • Coverage expectations • Digital signal • You have it or you don’t. • When it is gone, what do you do? • You must develop local redundant strategies (no different than you probably do today). 24 Tomorrow's Solutions Today

  25. REVIEW Learning Goal • Student ability to understand and explain basic differences between: • VHF and 700/800 MHz Radio spectrum • Analog and digital signal • Conventional and trunked radio systems. 25 Tomorrow's Solutions Today

  26. REVIEW Learning Objectives and Evaluation • Students will be able to explain, to the instructor’s satisfaction, the basic characteristics of VHF and 700/800 MHz radio spectrum. • Students will be able to explain, to the instructor’s satisfaction, the basic characteristics of analog and digital radio signals. • Students will be able to explain, to the instructor’s satisfaction, the basic differences between conventional and trunked radio systems. • Students will demonstrate knowledge and retention of training material through a testing process. 26 Tomorrow's Solutions Today

  27. Thank you for taking the time to view this presentation. We hope it was helpful. Feel free to contact us. On Target Training & Consulting, LLC Contact us: Ontarget.tc@msn.com 320-584-5416 27 Tomorrow's Solutions Today

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