{"id":226708,"date":"2021-02-24T15:40:25","date_gmt":"2021-02-24T15:40:25","guid":{"rendered":"https:\/\/racing-radios.com\/?page_id=226708"},"modified":"2024-01-09T19:54:01","modified_gmt":"2024-01-09T19:54:01","slug":"racing-radios-basics","status":"publish","type":"page","link":"https:\/\/racing-radios.com\/fr\/racing-radios-basics\/","title":{"rendered":"La Base des Radios en Course automobile"},"content":{"rendered":"\t\t
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Radio 101<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tFollowing is a list of familiar terms and their defenitions you will encounter in the racing communications world\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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ANR Rating For Headsets<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Noise Reduction Rating<\/b>\u00a0(NRR<\/b>) is a measure of the effectiveness of a hearing protection device to reduce noise levels. Higher values indicate greater\u00a0noise reduction<\/b>.\u00a0NRR<\/b>\u00a0values range up to approximately 30 dB. \u2026\u00a0NRR rating<\/b>\u00a0is based on a laboratory test where the hearing protection device is properly fit.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Analog Modulation<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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In\u00a0electronics\u00a0and\u00a0telecommunications,\u00a0modulation<\/b>\u00a0is the process of varying one or more properties of a periodic\u00a0waveform, called the\u00a0carrier signal<\/i>, with a separate signal called the\u00a0modulation signal<\/i>\u00a0that typically contains information to be transmitted. For example, the modulation signal might be an\u00a0audio signal\u00a0representing\u00a0sound\u00a0from a\u00a0microphone,\u00a0The carrier is higher in\u00a0frequency\u00a0than the modulation signal. The purpose of modulation is to impress the information on the carrier wave, which is used to carry the information to another location. In\u00a0radio communication\u00a0the modulated carrier is transmitted through space as a\u00a0radio wave\u00a0to a\u00a0radio receiver.<\/p><\/div><\/div><\/div>

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Antenna Gain<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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In\u00a0electromagnetics, an antenna\u2019s\u00a0power gain<\/b>\u00a0or simply\u00a0gain<\/b>\u00a0is a key performance number which combines the\u00a0antenna\u2018s\u00a0directivity\u00a0and\u00a0electrical efficiency. In a transmitting antenna, the gain describes how well the antenna converts input power into\u00a0radio waves\u00a0headed in a specified direction. In a receiving antenna, the gain describes how well the antenna converts radio waves arriving from a specified direction into electrical power. When no direction is specified, gain is understood to refer to the peak value of the gain, the gain in the direction of the antenna\u2019s\u00a0main lobe. A plot of the gain as a function of direction is called the gain pattern or\u00a0radiation pattern.<\/p><\/div><\/div><\/div><\/div><\/div>

\u00a0<\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Battery Capacity<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A battery\u2019s capacity is the amount of electric charge it can deliver at the rated voltage. The more electrode material contained in the cell the greater its capacity. A small cell has less capacity than a larger cell with the same chemistry, although they develop the same open-circuit voltage. Capacity is measured in units such as amp-hour (A\u00b7h). The rated capacity of a battery is usually expressed as the product of 20 hours multiplied by the current that a new battery can consistently supply for 20 hours at 68 \u00b0F (20 \u00b0C), while remaining above a specified terminal voltage per cell. For example, a battery rated at 100 A\u00b7h can deliver 5 A over a 20-hour period at room temperature. The fraction of the stored charge that a battery can deliver depends on multiple factors, including battery chemistry, the rate at which the charge is delivered (current), the required terminal voltage, the storage period, ambient temperature and other factors.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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COAXIAL CABLE<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Coaxial cable<\/strong>, or coax<\/strong> is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protective outer sheath or jacket. The term \u201ccoaxial\u201d refers to the inner conductor and the outer shield sharing a geometric axis.<\/p>

Coaxial cable is a type of transmission line, used to carry high-frequency electrical signals with low losses. It is used in such applications as connecting radio transmitters and receivers to their antennas. It differs from other shielded cables because the dimensions of the cable and connectors are controlled to give a precise, constant conductor spacing, which is needed for it to function efficiently as a transmission line.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Color Code<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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In a MOTOTRBO radio or repeater, there is a color code field which allows the selection of one of 15 colour codes. A radio which has been programmed with colour code 1 will not be able to transmit on a repeater configured with colour code 2 and so forth. A radio can be configured with multiple colour codes \u2013 one for each channel. A repeater can only be configured with one colour code.<\/p>

\u00a0<\/p>

Colour code is useful because it can prevent radios from one site or system mistakenly roaming to another site or system which uses the same frequencies. Although there is activity from the neighboring system, the radio will ignore all transmissions from the other system because it has a different colour code.<\/p>

This is also useful for telecommunication regulators who have to allocate the same frequency to two DMR licencees in the same region. The regulator simply has to specify a colour code in the licence conditions \u2013 much like PL\/DPL was used in analogue as a guard tone.<\/p>

There is a limitation of course, if two geographically adjacent radio systems use the same frequencies, yet use a different colour code, there will be audio quality issues in the area where radio users are able to receive signals from both systems at roughly the same signal strength.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Digital Modulation<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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More recent systems use\u00a0digital modulation<\/b>, which impresses a\u00a0digital signal\u00a0consisting of a sequence of\u00a0binary digits\u00a0(bits), a\u00a0bitstream, on the carrier. In\u00a0frequency shift keying\u00a0(FSK) modulation, used in\u00a0computer buses\u00a0and\u00a0telemetry, the carrier signal is periodically shifted between two frequencies that represent the two binary digits. In\u00a0digital baseband modulation<\/i>\u00a0(line coding) used to transmit data in\u00a0serial computer bus cables\u00a0and wired\u00a0LAN\u00a0computer networks\u00a0such as\u00a0Ethernet, the voltage on the line is switched between two amplitudes (voltage levels) representing the two binary digits, 0 and 1, and the carrier (clock) frequency is combined with the data. A more complicated digital modulation method that employs multiple carriers,\u00a0orthogonal frequency division multiplexing\u00a0(OFDM), is used in\u00a0WiFi\u00a0networks,\u00a0digital radio\u00a0stations and digital cable television transmission.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Duplex Mode<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tTwo-way radio systems usually use a single radio channel and operate in a half-duplex mode: only one user on the channel can transmit at a time, so users in a user group must take turns talking. The radio is normally in receive mode so the user can hear all other transmissions on the channel. When the user wants to talk he presses a \u201cpush-to-talk\u201d button, which turns off the receiver and turns on the transmitter; when he releases the button the receiver is activated again. Multiple channels are provided so separate user groups can communicate in the same area without interfering with each other. Other two-way radio systems operate in full-duplex mode, in which both parties can talk simultaneously. This requires either two separate radio channels or channel sharing methods such as time division duplex (TDD) to carry the two directions of the conversation simultaneously on a single radio frequency. A cell phone is an example of a full-duplex two-way radio. During a phone call, the phone communicates with the cell tower over two radio channels; an incoming one to carry the remote party\u2019s voice to the user, and an outgoing one to carry the user\u2019s voice to the remote party.\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t
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Duplexer<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A duplexer<\/strong> is an electronic device that allows bi-directional (duplex) communication over a single path. In radar and radio communications systems, it isolates the receiver from the transmitter while permitting them to share a common antenna. Most radio repeater systems include a duplexer. Duplexers can be based on frequency (often a waveguide filter), polarization (such as an orthomode transducer), or timing (as is typical in radar).<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Frequencies<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Frequency<\/b>\u00a0is the number of occurrences of a repeating event per\u00a0unit of time.\u00a0It is also referred to as\u00a0temporal frequency<\/b>, which emphasizes the contrast to\u00a0spatial frequency\u00a0and\u00a0angular frequency. Frequency is measured in\u00a0hertz\u00a0(Hz) which is equal to one occurrence of a repeating event per second. The\u00a0period<\/b>\u00a0is the duration of time of one\u00a0cycle\u00a0in a repeating event, so the period is the\u00a0reciprocal\u00a0of the frequency.\u00a0For example: if a newborn baby\u2019s heart beats at a frequency of 120 times a minute (2 hertz), its period,\u00a0T<\/i><\/span>, \u2014 the time interval between beats\u2014is half a second (60\u00a0seconds divided by 120\u00a0beats). Frequency is an important parameter used in science and engineering to specify the rate of\u00a0oscillatory\u00a0and\u00a0vibratory\u00a0phenomena, such as mechanical vibrations,\u00a0audio signals\u00a0(sound),\u00a0radio waves, and\u00a0light.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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FDMA Digital Protocol\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Frequency-division multiple access (FDMA)<\/strong> is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing the bandwidth of the channel into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user. Users can send data through a subchannel by modulating it on a carrier wave at the subchannel\u2019s frequency. It is used in satellite communication systems and telephone trunklines.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Firmware<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tFirmware is held in non-volatile memory devices such as ROM, EPROM, EEPROM, and Flash memory. Changing the firmware of a device was rarely or never done during its lifetime in the past but is nowadays a common procedure; some firmware memory devices are permanently installed and cannot be changed after manufacture. Common reasons for updating firmware include fixing bugs or adding features to the device. This requires ROM integrated circuits to be physically replaced, or EPROM or flash memory to be reprogrammed through a special procedure.\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t
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FDMA<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Frequency-division multiple access<\/b>\u00a0(FDMA<\/b>) is a\u00a0channel access method\u00a0used in some multiple-access protocols. FDMA allows multiple users to send data through a single\u00a0communication channel, such as a\u00a0coaxial cable\u00a0or\u00a0microwave\u00a0beam, by dividing the\u00a0bandwidth\u00a0of the channel into separate non-overlapping\u00a0frequency\u00a0sub-channels and allocating each sub-channel to a separate user. Users can send data through a subchannel by modulating it on a\u00a0carrier wave\u00a0at the subchannel\u2019s frequency. It is used in\u00a0satellite communication\u00a0systems and telephone trunklines.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Group ID in Two-way Radios\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Motorola Type II<\/b>\u00a0refers to the second generation\u00a0Motorola\u00a0trunked radio systems\u00a0that replaced fleets and subfleets with the concept of\u00a0talkgroups\u00a0and individual radio IDs. There are no dependencies on fleetmaps, therefore there are no limitations on how many radio IDs can participate on a talkgroup. This allows for greater flexibility for the agency. When scanning Motorola IDs, each Type II user ID appears as an even 4- or 5-digit number without a dash (example 2160).[1]<\/sup><\/p>

With the introduction of Type II, the \u201cSystem ID\u201d was also introduced. This is a four digit identifier unique to each trunking system. The purpose of the System ID is to allow radios to operate only on that specific system, and to identify each system. The System ID also allows for enhanced security because a radio now requires a System Key, unique to the System ID in order to be programmed onto any given system. Type I systems do not use unique System IDs, thus the possibility exists for overlapping coverage in busy areas.<\/p>

The term\u00a0SmartNet<\/i>\u00a0refers to a set of features that make Motorola Type I and II trunked systems\u00a0APCO-16\u00a0compliant. These include better security, emergency signaling, dynamic regrouping, remote radio monitoring, and other features.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Helmet Kits<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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a Helmet kit is an assembly of a noise cancelling\u00a0 Dynamic MICROPHONE , Male connector to mate with an Incar Wiring Harness\u00a0 and drivers erpiece connector to be mounted on the helmet. Driver can choose between straight cord or coil cord.
Recent regulations in a few road racing series in North America prohibits drilling a helmet to install the HELMET KIT, for safety purposes.\u00a0<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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\u201dIMSA\u201d and \u201dNASCAR\u201d Connectors\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The 2 most popular connectors for helmet kits are \u201d IMSA \u201d thye and \u201d NASCAR \u201d Type.
in the early days the switchcraft 297 3 contacts connector was used by numerous NASCAR drivers in US\u00a0
NEXUS TP120 4 contacts connector was adopted in road racing and is known as \u201d IMSA \u201d type\u00a0
The new trend is to go IMSA in all series.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Mobile radio<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A sales person or radio repair shop would understand the word mobile to mean vehicle-mounted:<\/strong> a transmitter-receiver (transceiver) used for radio communications from a vehicle. Mobile radios are mounted to a motor vehicle usually with the microphone and control panel in reach of the driver. In the US, such a device is typically powered by the host vehicle\u2019s 12 Volt electrical system.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Noise cancelling Microphone\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tAll such microphones have at least two ports through which sound enters; a front port normally oriented toward the desired sound and another port that\u2019s more distant. The microphone\u2019s diaphragm is placed between the two ports; sound arriving from an ambient sound field reaches both ports more or less equally. Sound that\u2019s much closer to the front port than to the rear will make more of a pressure gradient between the front and back of the diaphragm, causing it to move more. The microphone\u2019s proximity effect is adjusted so that flat frequency response is achieved for sound sources very close to the front of the mic \u2013 typically 1 to 3 cm. Sounds arriving from other angles are subject to steep midrange and bass rolloff. Commercially and militarily useful noise-canceling microphones have been made since at least 1935 (Amelia Earhart used one on her 1935 flight from Hawaii to California) and have been made since the 1940s by Roanwell, Electro-Voice and others.\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t
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PTT Switch\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Push-to-talk (PTT),<\/strong> also known as press-to-transmit<\/b>, is a method of having conversations or talking on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Private line tones ( PL and DPL )\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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in\u00a0telecommunications,\u00a0Continuous Tone-Coded Squelch System<\/b>\u00a0or\u00a0CTCSS<\/b>\u00a0is one type of\u00a0circuit\u00a0that is used to reduce the annoyance of listening to other users on a shared\u00a0two-way radio\u00a0communications channel. (See\u00a0squelch.) It is sometimes referred to as\u00a0tone squelch.<\/b>\u00a0It does this by adding a low frequency audio tone to the voice. Where more than one group of users is on the same radio frequency (called\u00a0co-channel users<\/i>), CTCSS circuitry mutes those users who are using a different CTCSS tone or no CTCSS. It is sometimes referred to as a\u00a0sub-channel<\/b>, but this is a misnomer because no additional channels are created. All users with different CTCSS tones on the same channel are still transmitting on the identical\u00a0radio frequency, and their transmissions interfere with each other; however; the interference is masked under most (but not all) conditions. The CTCSS feature also does not offer any security.<\/p>

A receiver with just a\u00a0carrier or noise squelch\u00a0does not suppress any sufficiently strong signal; in CTCSS mode it unmutes only when the signal also carries the correct sub-audible audio tone. The tones are not actually below the range of human hearing, but are poorly reproduced by most communications-grade speakers and in any event are usually filtered out before being sent to the speaker or headphone. CTCSS can be regarded as a form of\u00a0in-band signaling.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Power ( Watts )\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A radio frequency power amplifier (RF power amplifier)<\/strong> is a type of electronic amplifier that converts a low-power radio-frequency signal into a higher power signal. Typically, RF power amplifiers drive the antenna of a transmitter. Design goals often include gain, power output, bandwidth, power efficiency, linearity (low signal compression at rated output), input and output impedance matching, and heat dissipation.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Repeaters<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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in\u00a0telecommunications, a\u00a0repeater<\/b>\u00a0is an electronic device that receives a\u00a0signal\u00a0and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some types of repeaters broadcast an identical signal, but alter its method of transmission, for example, on another frequency or\u00a0baud rate.<\/p>

There are several different types of repeaters; a\u00a0telephone repeater<\/b>\u00a0is an\u00a0amplifier\u00a0in a\u00a0telephone line, an\u00a0optical repeater\u00a0is an\u00a0optoelectronic\u00a0circuit that amplifies the light beam in an\u00a0optical fiber cable; and a\u00a0radio repeater\u00a0is a\u00a0radio receiver\u00a0and\u00a0transmitter\u00a0that retransmits a radio signal.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Radio Wiring Harness\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tRadio Wiring Harnesses are connecting the Incar two-way radio with the drivers helmet kit and steering wheel PTT switch. It is a critical piece of equipment of your radio system since it is used in a very hostile RF environment next to all other electrical circuits including ignitions in a race car. Good wiring sheilding of the harness is essentials to eliminate unwanted noises.\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Sensitivity for Receivers\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tThe signal strength of radio waves decreases the farther they travel from the transmitter, so a radio station can only be received within a limited range of its transmitter. The range depends on the power of the transmitter, the sensitivity of the receiver, atmospheric and internal noise, as well as any geographical obstructions such as hills between transmitter and receiver. AM broadcast band radio waves travel as ground waves which follow the contour of the Earth, so AM radio stations can be reliably received at hundreds of miles distance. Due to their higher frequency, FM band radio signals cannot travel far beyond the visual horizon; limiting reception distance to about 40 miles (64 km), and can be blocked by hills between the transmitter and receiver. However FM radio is less susceptible to interference from radio noise (RFI, sferics, static) and has higher fidelity; better frequency response and less audio distortion, than AM. So in many countries serious music is only broadcast by FM stations, and AM stations specialize in radio news, talk radio, and sports. Like FM, DAB signals travel by line of sight so reception distances are limited by the visual horizon to about 30\u201340 miles (48\u201364 km).\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t
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Simplex Mode\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The\u00a0International Telecommunication Union\u00a0definition is a communications channel that operates in one direction at a time, but that may be reversible; this is termed\u00a0half duplex\u00a0in other contexts. A\u00a0duplex\u00a0communication channel requires two simplex channels operating in opposite directions.<\/p>

For example, in TV and radio\u00a0broadcasting, information flows only from the transmitter site to multiple receivers. A pair of\u00a0walkie-talkie\u00a0two-way radios\u00a0provide a simplex circuit in the ITU sense; only one party at a time can talk, while the other listens until it can hear an opportunity to transmit. The transmission medium (the radio signal over the air) can carry information in only one direction.<\/p>

The old\u00a0Western Union\u00a0company used the term simplex when describing the\u00a0half-duplex\u00a0and simplex capacity of their new\u00a0transatlantic telegraph cable\u00a0completed between\u00a0Newfoundland\u00a0and the\u00a0Azores\u00a0in 1928.\u00a0The same definition for a simplex radio channel was used by the\u00a0National Fire Protection Association\u00a0in 2002.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Sound Pressure Level SPL\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Sound pressure<\/b>\u00a0or\u00a0acoustic pressure<\/b>\u00a0is the local\u00a0pressure\u00a0deviation from the ambient (average or equilibrium)\u00a0atmospheric pressure, caused by a\u00a0sound wave. In air, sound pressure can be measured using a\u00a0microphone, and in water with a\u00a0hydrophone. The\u00a0SI unit\u00a0of sound pressure is the\u00a0pascal\u00a0(Pa).<\/p>

The lower limit of audibility is defined as SPL of\u00a00 dB<\/span>, but the upper limit is not as clearly defined. While\u00a01\u00a0atm<\/span>\u00a0(194 dB peak<\/span>\u00a0or\u00a0191 dB SPL<\/span>) is the largest pressure variation an undistorted sound wave can have in\u00a0Earth\u2019s atmosphere\u00a0(i.e. if the thermodynamic properties of the air are disregarded, in reality the sound wave become progressively non-linear starting over 150\u00a0dB), larger sound waves can be present in other\u00a0atmospheres\u00a0or other media such as under water or through the Earth.<\/p>

\"\"<\/a>

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Equal-loudness contour, showing sound-pressure-vs-frequency at different perceived loudness levels<\/p><\/div><\/div><\/div>

Ears detect changes in sound pressure. Human hearing does not have a flat\u00a0spectral sensitivity\u00a0(frequency response) relative to frequency versus\u00a0amplitude. Humans do not perceive low- and high-frequency sounds as well as they perceive sounds between 3,000 and 4,000\u00a0Hz, as shown in the\u00a0equal-loudness contour. Because the frequency response of human hearing changes with amplitude, three weightings have been established for measuring sound pressure: A, B and C.\u00a0A-weighting\u00a0applies to sound pressures levels up to\u00a055 dB<\/span>, B-weighting applies to sound pressures levels between\u00a055 dB<\/span>\u00a0and\u00a085 dB<\/span>, and C-weighting is for measuring sound pressure levels above\u00a085 dB<\/span>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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System Range ( Radio )\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tThe radio system Range is the distance two radios can communicate intelligibely. This all depends on RADIOS RF POWER, RADIO SNSITIVITY , physical obstacles and the RF band they are using.\n\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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TDMA Digital Radio Protocol\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Time-division multiple access (TDMA)<\/strong> is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots.[1] The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity. Dynamic TDMA<\/strong> is a TDMA variant that dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Unipole Antennas\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A monopole antenna<\/strong> is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane.[1][2][3] The driving signal from the transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the lower end of the monopole and the ground plane. One side of the antenna feedline is attached to the lower end of the monopole, and the other side is attached to the ground plane, which is often the Earth. This contrasts with a dipole antenna which consists of two identical rod conductors, with the signal from the transmitter applied between the two halves of the antenna.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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OMNIDIRECTIONAL ANTENNAS\n<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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in radio communication, an omnidirectional antenna<\/strong> is a class of antenna which radiates equal radio power in all directions perpendicular to an axis (azimuthal directions), with power varying with angle to the axis (elevation angle), declining to zero on the axis. When graphed in three dimensions (see graph) this radiation pattern is often described as doughnut-shaped. Note that this is different from an isotropic antenna, which radiates equal power in all directions, having a spherical radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile devices that use radio such as cell phones, FM radios, walkie-talkies,<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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DMR<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Digital mobile radio<\/b>\u00a0(DMR<\/b>) is a limited open digital\u00a0mobile radio\u00a0standard defined in the\u00a0European Telecommunications Standards Institute\u00a0(ETSI) Standard TS 102 361 parts 1\u20134\u00a0and used in commercial products around the world. DMR, along with\u00a0P25 phase II\u00a0and\u00a0NXDN\u00a0are the main competitor technologies in achieving 6.25\u00a0kHz equivalent bandwidth using the proprietary\u00a0AMBE+2\u00a0vocoder. DMR and P25 II both use two-slot\u00a0TDMA\u00a0in a 12.5\u00a0kHz channel, while NXDN uses discrete 6.25\u00a0kHz channels using frequency division and\u00a0TETRA\u00a0uses a four-slot TDMA in a 25 kHz channel.<\/p>

DMR was designed with three tiers. DMR tiers I and II (conventional) were first published in 2005, and DMR III (Trunked version) was published in 2012, with manufacturers producing products within a few years of each publication.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

Radio 101 Following is a list of familiar terms and their defenitions you will encounter in the racing communications world ANR Rating For Headsets Noise Reduction Rating\u00a0(NRR) is a measure of the effectiveness of a hearing protection device to reduce noise levels. Higher values indicate greater\u00a0noise reduction.\u00a0NRR\u00a0values range up to approximately 30 dB. \u2026\u00a0NRR rating\u00a0is […]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"footnotes":""},"class_list":["post-226708","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/pages\/226708","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/comments?post=226708"}],"version-history":[{"count":42,"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/pages\/226708\/revisions"}],"predecessor-version":[{"id":228708,"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/pages\/226708\/revisions\/228708"}],"wp:attachment":[{"href":"https:\/\/racing-radios.com\/fr\/wp-json\/wp\/v2\/media?parent=226708"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}