Sumner County Emergency Communications January

“Left click” anywhere on the screen to advance to the next slide. “Right click”, then “left click” the Previous Screen command on the opening dialog box to return to the previous slide.. SCEC – Basic Radio Operations for Responders, January

There are many forms of “radio” in use in society today. SCEC – Basic Radio Operations for Responders, January AM/FM Radio Two way Radio Remote control devices Other Regardless of the use, “radio” is electro- magnetic waves travelling through the atmosphere.

Radio is a rapidly oscillating electric current. “Frequency” is the number of cycles a radio wave makes in one second. SCEC – Basic Radio Operations for Responders, January

Radio waves travel at the speed of light which is 186,000 feet per second. The number of cycles per second is called the frequency. One cycle per second is equal to 1 Hertz SCEC – Basic Radio Operations for Responders, January

Frequencies are divided into segments called “bands”. The Voice Band (between 300Hz (Hertz) and 3kHz are the lowest frequencies audible to the human ear. Frequencies below 300Hz cannot be heard. SCEC – Basic Radio Operations for Responders, January VLF – Very Low Frequency LF – Low Frequency MF – Medium Frequency HF – High Frequency VHF – Very High Frequency UHF – Ultra High Frequency SHF – Super High Frequency EHF – Extremely High Frequency

“Land mobile radio” bands are reserved in the 25-50Mhz, MHz, MHz, MHz, MHz, and MHz ranges. “LMR” is available for police, fire, EMS, business, commercial, and other purposes. SCEC – Basic Radio Operations for Responders, January Before the transition to UHF ( MHz) in the 1980’s, most public safety agencies were in the VHF “Lo” Band, generally in the to 47.00MHz frequency range. While Sumner County uses some UHF “Hi” frequencies in the MHz range, frequencies are predominantly UHF “Lo” in the MHz range.

Radio waves are emitted much the same way as light is emitted. Picture the antenna on your walkie-talkie or emergency vehicle as a light bulb, the radio waves traveling the same pattern as light travels from the bulb. SCEC – Basic Radio Operations for Responders, January

Just like light, radio waves cannot penetrate solid objects such as concrete walls, trees, earth, etc. Some radio waves are absorbed as heat into the object they strike. Other radio waves are reflected from the object to another direction. Some radio waves are diffracted, and can go around or over objects. The remaining radio waves are dispersed into the atmosphere. SCEC – Basic Radio Operations for Responders, January

Generally, the lower the frequency, the more adaptable radio waves are to diffraction and dispersion. Higher frequencies tend to travel in a straight line and are absorbed or reflected. This causes problems when broadcasting on a handheld radio from inside a building, or when there is a building or other solid object between your radio and the repeater. SCEC – Basic Radio Operations for Responders, January

Repeated systems, which allow for greater radio range on high frequency systems, use two radio frequencies to complete an audio path between two radios. Radios transmit on one frequency (F1) and received on a second frequency (F2) Repeaters receive on the first frequency (F1), and transmit on the second frequency (F2). SCEC – Basic Radio Operations for Responders, January

When you transmit on F1, it cannot be heard by other radios set up to receive on F2. Because the repeater is designed to receive on F1, the repeater receives your signal, then retransmits with higher power and with greater range on F2, which is received by other radios. If you cannot access the repeater, other radios cannot hear you. Remember, when you transmit, you are talking to the repeater and NOT to other radios. SCEC – Basic Radio Operations for Responders, January

Some channels have the nomenclature “D” behind them, meaning they are “direct” channels. These channels are tuned to transmit on F2. When you transmit “direct”, you can talk to other radios (if you are in radio range) and bypass the repeater. SCEC – Basic Radio Operations for Responders, January DIRECT

With repeater operations, you must pause after pressing the PTT button on your microphone or radio to wait for the repeater to activate. The general rule of thumb is to count to two before you begin talking. SCEC – Basic Radio Operations for Responders, January Delay

Know the location of the repeater site you are attempting to access. A – LTR Trunking Tower 700 N. Hoover Rd B – Ops 1 and Ops E. 20 th St South C – Ops S. West Rd D – Ops W. 170 th St South E – Ops N. Oliver Rd F – KDOT Tower 500 W. 10 th Avenue SCEC – Basic Radio Operations for Responders, January

1.You must be in range of the repeater before you can communicate by radio (except when using “direct”. When using “direct”, you must be within radio range of your intended receiver; range is greatly reduced when bypassing the repeater. 2.You must be in a position for your radio waves to reach the repeater, regardless of range. If you cannot access the repeater, try moving a few feet to avoid reflection or absorption of radio waves by solid objects. 3.Height is a much greater advantage than power. The higher you can get, the better chance you will have of accessing the repeater. 4.Be aware that you may not be able to transmit using a handheld radio from within a building. 5.Maintain your radio is good working condition. The radio should be periodically tested, batteries replaced frequently, and antennas and coax intact and in good working order. 6.Handheld radios operate at a much lower power than mobile radios. Their range therefore, is much less than a mobile radio. SCEC – Basic Radio Operations for Responders, January

Training Classes “Basic Radio Communications”, “Radio Communications for Law Enforcement”, “Radio Communications for the Fire Service”, “Radio Communications for EMS”, Web “Radio”, Wikipedia; “How Radio Works”, How Stuff Works; SCEC – Basic Radio Operations for Responders, January