Repeater Related Terminology
Submissions of terminology from the users of the Repeater-Builder yahoogroup

From Ric Sohl   KK5RIC

So What's The COR or COS??

The Carrier Operated Switch used to be called COR.... Short for Carrier Operated Relay. This is going back to the early days of repeaters in which all the repeaters had tubes in them, and all circuit switching was done by relays. Nowadays most of the repeaters are solid state, except for a few which have tubes in the final amplifier, so now we call it COS or "Channel Busy" or ...
So you ask how does it work and what's the purpose, and were can I find this COS on a receiver? The function of the carrier operated switch is to tell the repeater controller, if the repeater has one, that the receiver squelch is open, and that there is a signal there. If the controller is set up for Carrier Squelch (CSQ) it then turns on and off the repeater transmitter. If the repeater does not have a controller, the COS simply does the function of turning on and off the transmitter.   The COS signal can be either a set of relay contacts or a voltage that swings high or low to give either a + voltage or ground with the receiver active, (noise or a signal.) On some receivers the COS uses a relay and that has a dry contact to ground, and you won't see a swinging voltage, a 5k or so pullup resistor connected 12 volts, makes the COS voltage swing. The squelch circuit rectifies the hissing noise, its the noise that we hear when the squelch is open and no signal is present on the fm receiver. Sometimes this noise is amplified and is applied to diodes to converted to a dc voltage, some other times to a voltage doubler to get a greater level of swinging voltage. That voltage is compared to the squelch pot and if it's greater the squelch stays closed, if it's less the squelch opens. There's another way to get a COS voltage from a receiver, that is with a VOX circuit on the receiver audio output, it does not work properly on a repeater, (if someone has a full quieting signal and there is a pause in the speech the VOX closes) so I won't go in detail with it here. Some AM receivers have COS's also.. not just the FM ones, the major difference between the two are the FM receivers the COS and squelch works much better and is harder to be fooled by noise....by the way, airports with towers use AM receivers with COS. The COS squelch circuit has been used in repeater receivers for years, long before the tone squelch came to be very popular. Manufactures paid special attention to the squelch circuits in their receivers, Motorola even made a special IC for their Micor series radios.

Another contributor offers:
Access Code - Usually a series of DTMF tones transmitted to a repeater to perform control functions.
ADPCM: Adaptive Differential Pulse Code Modulation, is a form of voice (or other audio) coding and decoding algorithm used in digital equipment to handle analog signals (like a voice). For example, a voice IDer may use ADPCM to to store the audio signal in a digital memory chip. Some ROIP systems use ADPCM to encode and decode the audio at each end of the digital link. Another method of voice coding and decoding is GSM or PCM.
Alligator timer - A timer function of a repeater controller that limits the length of time the transmitter will remain keyed with out a pause.   Typically the timer is set between 3 and 5 minutes.  (Also see: Time-out Timer)
Autopatch - a device that interfaces a repeater to the telephone system and allows repeater users to make outgoing phone calls. Some offer incoming as well.
Beam Tilt - Generally refers to the angular tilt of the main lobe of a antenna in the elevation pattern above or below 0 degrees elevation.   Often considered in high repeater locations.
Break - A term used in an emergency to interrupt a conversation in progress.
Carrier delay - When you're monitoring a repeater and the person talking into the repeater un-keys his transmitter, you hear the squelch tail from the repeater's receiver. Then, the repeater's transmitter remains keyed anywhere between 1/2 second and 5 seconds, in other words it's transmitter "hangs" on during the "carrier delay" before it "drops out". Some repeaters insert a beep or other type of tone or multiple tones during the hang time. This tone or tones can be a "courtesy beep" or it can be telemetry signaling that certain links or other devices are connected. The purpose of the carrier delay timer on a repeater is to eliminate the repeater's transmitter from chattering on & off when the repeater's receiver is receiving a noisy, choppy signal. In the early days when all the repeaters were based on vacuum tubes and used mechanical relays this timer saved much wear and tear on those relays. Today's solid state repeaters do not have this issue, but a chattering transmitter combined with an already choppy fluttering signal into a repeater is even more difficult to hear. Another purpose for the carrier delay is for testing. You can "kerchunk" (key your radio into a repeater momentarily) & monitor it's signal level coming back to you.
COR - "Carrier Operated Relay"  A relay that is usually derived from the squelch circuit of a receiver signaling the presence of a signal at the receiver.This signal tells the repeater controller when a valid signal is present. See squelch circuit.
COS - "Carrier Operated Signal", "Carrier Operated Squelch" or "Carrier Operated Switch" is a relayless version of the COR. It's a digital signal that switched between two logic levels (usually +5v and ground). See squelch circuit.
Courtesy Beep - An audible indication that the repeater is clear and you may go ahead and transmit. This beep occurs after the squench tail and before the repeater transmitter drops out.
Courtesy Tone - see courtesy beep.
CTCSS - "Continuous Tone Coded Squelch System" CTCSS is a series of sub-audible tones which are standard on most new radios.  An audible cousin of CTCSS is DTMF.  These tones often perform control functions.  Some repeaters may require a sub-audible tone before activating, others use it to perform functions such as turning all trunks on and off when a specific tone is present. (Also see: Tone Squelch, CG, ETS, PL, TOS)
De-emphasis - The reduction in audio level in the audio circuits of a receiver at the rate of 6 dB per octave.  The increase of level applied at the TX end assists in overcoming noise appearing in the higher frequencies of the audio bandpass.
Desense - A problem characteristic of many radio receivers in which a strong RF signal overloads the receiver, reducing sensitivity.
Deviation - the act of pushing a transmitter off center frequency at an audio rate. See "Modulation"
Doubling - two or more stations transmitting simultaneously on the same channel. Sometimes the one with the strongest carrier wins, other times it's just grunge.
Downlink - The radio signal which carries information from the satellite to the satellite terminal. Can also be used to describe the signal from the repeater to the users.
Drop Out Timer - see carreir delay.
DTMF - "Dual Tone Multiple Frequency"  A series of audible tones used for remote command and control of equipment.  Always identify yourself and your intent when transmitting DTMF tones AKA touchtone.
Duplexer - A filtering device that provides a high level of isolation between frequencies.  It permits a station to simultaneously transmit and receive on one antenna.
ETS - "Electronic Tone Squelch" is the Canadian Marconi Company version of tone squelch.  ETS is a series of sub-audible tones which has the ability of performing control functions.  (Also see, Tone Squelch, CTCSS, CG & PL.)
Frequency Coordinator - an individual or group responsible for assigning frequencies in an area. Usually a unappreciated, overworked volunteer.
Full Duplex - Radio communication using two frequencies simultaneously (one for receive, one for transmit)
Geostationary - Describes the orbit position that causes the satellite to appear as if it is stationary to observers on earth.  It appears this way because the orbit period of the satellite is the same as the daily rotational period of the earth.
GSM: Global System for Mobile Communications, is a form of voice coding and decoding algorithm used in digital equipment to handle analog signals (like a voice). For example, a voice IDer may use GSM to to store the audio signal in a digital memory chip. Some ROIP systems use GSM to encode and decode the audio at each end of the digital link. Another method of voice coding and decoding is ADPCM or PCM.
Half Duplex - Radio communication using two frequencies sequentially (one for receive, one for transmit)
Hang In Timer - see carrier dealy
Harmonic - A signal occurring at some integral multiple of a fundamental frequency.
Input Frequency - Commonly term for the frequency you use when transmitting to a repeater; sometimes called teh uplink frequency.
Intermodulation -  is the creation of a new frequency by mixing 2 or more >other frequencies.  This mixing only takes place in either the Receiver, Transmitter or other connecting devices.
ISDN: Integrated Services Digital Network, is a digital telephone connection that uses digital signals instead of analog signals to handle the transfer of signaling and speech. It's basically two channels of a T1 link. Two humorous translations of ISDN are "I Still Don't Know", and "Innovations Subscribers Don't Need".
Linking system -  The linking system refers to the dedicated point-to-point radio links between repeaters on a network. These dedicated radios talk only to other link radios and usually have beam antennas on both ends, or sometimes if multiple links terminate at one site there will be a gain vertical at that site.  One should not access the network via a link radio.   (Also see: Trunk)
Octave - An Octave when referring to frequency is that point when the frequency is doubled.  Every time we double the frequency, we increase it by 1 octave.
Offset - When referred to as a Repeater Frequency variable, it is the >standard frequency step needed to work a duplex repeater; the repeater receiver frequency. Each band has its own standard "offset", for example 5MHz on the USA UHF (440MHz) band.
Output - When referred to as a Repeater Frequency, it is a frequency which a repeater transmits on.
PCM: Pulse Code Modulation, is a form of voice coding and decoding algorithm used in digital equipment to handle analog signals (like a voice). For example, a voice IDer may use PCM to to store the audio signal in a digital memory chip. Some ROIP systems use PCM to encode and decode the audio at each end of the digital link. Another method of voice coding and decoding is ADPCM or GSM.
PL - "Private Line" is the Motorola trademark of Tone squelch.   PL is a series of sub-audible tones which has the ability to perform control functions.   (Also see: Tone Squelch, CTCSS & ETS)
Port - when referred to as a Repeater Port, it identifies a  radio, serial,
phone patch or other I/O option on the repeater.
PSTN: Public Switched Telephone Network, which refers to the international telephone system based on copper wires and switched circuits for carrying analog voice data.
PTT: Push-to-Talk, A signal to a radio transmitter, which controls the actual transmission of radio frequency energy over the air. Historically the name comes from the Push-To-Talk button on the side of a microphone.
Quieting - When referring to signal reports, quieting pertains to the amount of limiter quieting in an FM receiver.  A full-quieting signal would be one that completely eliminates all background noise from the receiver.
Repeater -  A simple voice repeater consists of a transmitter and a receiver, and operates in a manner similar to a base station except the transmitter is used to re-transmit the same signal as received by the receiver.  The repeater is almost always a full duplex operation.
Repeater Network - The connecting of 2 or more repeaters which will usually increase a common user area or diversify frequencies or bands.
Reset - As pertaining to the "Repeater User Codes", it means to turn the repeater controller to its normal state of operation.
Reverse Autopatch -  the capability of some phone patches to initiate a call from a phone, out to a repeater user via dialing into the repeater autopatch.
Reverse Split - Operating duplex on a reverse frequency split compared to what is considered "normal" for the situation.
RoIP: Radio over Internet Protocol, (compared to VoIP) not only converts voice to a digital format that can be sent over the Internet or another IP based network, but also convert PTT and COR control signals that are essential for seamless for radio interoperability. Also include are extra delay and jitter compensation.
ROIP Gateway: a device used to connect a land mobile radio device to another device over an IP-based network. The unit creates a network link that passes both voice and control signals either one direction (a one-way link) or both directions (a full duplex link). RUS - a logic signal that takes into account the presence or absence of a carrier signal, the presence or abscence of any CTCSS tone, and the position opf the CTCSS switch (in tone mode or in carrier mode). When active the signal indicates that the receiver audio is unmuted.
SAREX - "Shuttle Amateur Radio Experiment" An educational program in which the space Shuttle Astronauts communicate with amateurs and schools using voice and packet.
Spectrum - A term used to describe a range of frequencies.
Squelch circuit - All receivers have a section, called a "noise operated squelch circuit", or squelch for short. The squelch circuit samples the white noise that is on channel, and goes away when there is a signal. This section generates a DC voltage that is compared to the position of the squelch control and switches a voltage on or off when the receiver hears a carrier signal. This voltage is used to mute the speaker when there is no signal, and unmutes it when there is a signal, sometimes in concert with a tone decoder (see CTCSS).   This voltage can also feed a output signal driver (COS) or a relay driver (COR). Either way, the control signal is fed to a repeater controller or in the tube days the COR contacts would key the transmitter in a repeater.   By adding a large capacitor on the relay coil circuit you could add a carrier delay that keept the transmitter keyed when the receiver was receiving a weak signal that was fluttering or dropping out.
Squelch Tail - The short burst of white noise heard on an FM receiver between the time a signal ceases to be received and the squelch circuit actually mutes the audio output (the speaker audio). This term is often confused with the "carrier delay", "hang time" or "drop out delay" with respect to a repeater. When you're monitoring a repeater and the person talking into the repeater un-keys his transmitter, the short burst of white noise (rushing sound) you hear is the squelch tail from the repeater's receiver. Then, the repeater's transmitter remains keyed anywhere between 1/2 second and 5 seconds, in other words it's transmitter "hangs" on during the "carrier delay" before it "drops out", this is what's known as the hang time or drop out delay. Some repeaters insert a beep or other type of tone or multiple tones during the hang time. This tone or tones can be a "courtesy tone" or it can be telemetry signaling that certain links or other devices are connected. At the end of this time when the repeater's transmitter un-keys, you will hear a squelch tail from your radio's receiver. When operating simplex with another station, every time the station(s) transmitting to you un-keys, you will hear a squelch tail from your receiver.
TCP: Transport Control Protocol is an additional layer on top of the Internet Protocol, which ensures delivery of packets, sent across the network. It can handle situations such as lost packets or packets arriving out of order.
Time-out timer - A function of a repeater controller that limits the amount of time the transmitter will remain keyed with out a pause.  Typically the timers are set to between 3 and 5 minutes. (Also see: Alligator)
Tone Squelch - Is a generic name for many "Sub-audible tone systems".  The principle is that a receiver will not allow any audio to be routed to the speaker (or repeater transmitter) unless it is accompanied by the appropriate sub-audible tone. (Also see: CTCSS, ETS & PL)
TOR - Tone Operated Relay - a relay operated by the CTCSS decoder. GE had a TOR board for their stations.
TOS - Tone Operated Squelch - another name for CTCSS
TOT - see Time out timer
Trunk -  The trunk or trunking system refers to the dedicated radio links between repeaters on a network. These dedicated radios talk only to other trunking radios.  One should not access the network via a trunk radio. (Also see: Link)
Uplink - Referring to Earth /Satellite communications, it is that portionthat brings traffic from earth to the satellite. In repeater communications, it's the user-to-repeater frequency.
UHF - "Ultra High  Frequencies" ; radio frequencies from 300 to 3000 MHz.
VHF - "Very High Frequency"; radio frequencies from 30 to 300 MHz.
VOCODER: Voice Coder / Decoder, is an algorithm use by VOIP and ROIP systems that reduces speech signals to slowly varying signals transmittable over TCP/IP networks to conserve network bandwidth.
VoIP: Voice over Internet Protocol is a method of sending voice communications across a digital network.

THE  R-S-T SYSTEM

The R S T system of signal reporting is an internationally recognized
method of reporting signal quality.  The "R" stands for readability, the
"S" for signal strength, and "T" for tone in CW.

Readability
1 - Unreadable
2 - Barely readable, occasional words distinguishable
3 - Readable with considerable difficulty
4 - Readable with practically no difficulty
5 - Perfectly readable

Signal Strength
1 - Faint signal, barely perceptible
2 - Very weak signal
3 - Weak signal
4 - Fair signal
5 - Fairly good signal
6 - Good signal
7 - Moderately strong signal
8 - Strong signal
9 - Extremely strong signal

Tone (only on a morse code contact)
1 - Sixty cycle a.c. or less, very rough and broad
2 - Very rough a.c., very harsh and broad
3 - Rough a.c. tone, rectified but not filtered
4 - Rough note, some traces of filtering
5 - Filtered rectified a.c. but strongly rippled modulated
6 - Filtered tone, definite trace of ripple modulated
7 - Near pure tone, trace of ripple modulation
8 - Near perfect tone, slight trace of modulation
9 - Perfect tone, no trace of ripple or modulation

If you give a signal report of 5-by-9, you are indicating that the signal is extremely strong.

From Kevin Custer  W3KKC:

Precipitation Static   This phenomena exists when a charged cloud is near, and an aurora is formed around the antenna. As the static is built up on the antenna, receiver desensitization occurs.

From Rick Sohl - KK5RIC:
Reverse burst was used in the Olden Golden days of yore, when we used mechanical tuned reeds to decode and encode CTCSS tones.  The decode reeds would keep the squelch open as they coasted to a stop and the radio would be on open squelch, and you would hear the noise squelch close with a "Ker-Chunk" sound. The reverse burst circuitry turned the CTCSS tone around 180 degrees and this caused the reeds to slam to a stop, causing the receiver squelch to shut before the user heard any squelch noise. "Ker-Chunk"

Another contribuitor offers:

Antenna: Every radio has an antenna. The antenna radiates radio frequency energy that you create when you press the push-to-talk button. Antennas come in various shapes and sizes and serve different purposes. Some direct energy all directions (omnidirectional) and some direct energy in one direction or to a general area (beam, corner reflector.)

Beam: A directional antenna.

Boom: A beam is built on a boom. A long horizontal pole on which the antenna elements are mounted. This is the one that bends in a storm.

Bunker: The term often refers to the small buildings at the foot of a tower that contain the radio repeater(s).

CCT = carrier control timer, i.e. PTT time-out timer (the term is used mostly in GE documentation). When the driver sits on his microphone this timer saves the mobile transmitter and frees up the channel.

CG: GEs abbreviation for CTCSS, called Channel Guard. Also trademarked.

Channel: This refers to to the channel on the radio that you use or ... (see Channel Pair)

Channel Busy: see COR

Channel Guard: General Electric's trademarked name for CTCSS

Channel pair: A repeater uses a pair of frequencies, one to listen on, one to transmit on (simultaneously). Frequently a repeater channels/frequencies are also referred to as a channel pair.

COR / COS: A signal from the repater receiver to the repeater controller saying that there is a carrier on the receiver frequency. The controller may AND this signal with one from the subaudible decoder, or it may key up the repeater transmitter on carrier alone. A COR generally has a relay in it, a COS circuit is relayless.

CTCSS: Continuous Tone Coded Squelch System. This is the process by which a radio signal is transmitted containing a sub-audible tone. Only a receiver that is set up to detect the tone will un-mute its receiver. Using CTCSS is a way of limiting what you hear to only what you want to hear on the frequency you are using. The tones range from 67 to about 200hz.

DCS: Digital Coded Squelch. This is similar to CTCSS above but uses a digital signal rather than an analog signal.

Direct: When both persons or a group of persons talk on one radio channel to each other rather than using a repeater they are said to be talking direct. Also called Simplex or Talk Around.

DPL: Digital Private Line. Motorola's trademarked acronym for DCS.

DTMF: An abbreviation for "Dual Tone, MultiFrequency". Also known as touchtone.

Duplexer: The magic box that allows a repoeater to use one antenna to receive and trasnmit at the same time.

HT: An acronym for Handie-talkie

Hand-held: The same as HT, walkie-talkie, portable hand held radio.

Heliax: A trademarked term (by Andrew Corp) for their stiff, corrugated, solid copper shielded coaxial cable with very low loss characteristics that is used to connect a repeater or base radio to an antenna. It is highly preferred over standard coaxial cable because of the low loss characteristics. A "slang" term frequently used is "hard-line", but real hardline is based on stiff tubular pipe, not a corrugated flexible feedline.

Intermod - a contraction of Intermodulation: an often misused term that has become a generic terms used to describe just about any type of receiver interference. Like Klenex has become the name for any brand of facial tissue. Intermod is a very specific type of phenomenon and for accuracy, should only be used to describe intermodulation issues and not mixes, adjacent channel interference, etc.

Mast: The pole on which antennas are typically mounted.

Mount: The hardware used to attach the antenna to the car body, mounting pole or tower.

Machine: Ham slang for radio repeater.

MaxTrac: Motorola trademark name for a series of commercial quality radios that can be used on GMRS frequencies among others. About the size of a CB radio, usually underdash.

Mobile: using radios in a car, truck, bicycle, or on foot.

Mobile unit number: Some GMRS licensees adopt mobile unit identifiers for use on repeaters or on simplex. This is in addition to their FCC assigned call signs.

Mountain top: A reference to the location of a repeater antenna. It means literally what it says. Refers to the top of a mountain where a radio repeater site might be located.

PL: an abbreviation for Private Line, Motorolas trademark for CTCSS.

Portable: Carrying radio with you, or refers to a hand held radio.

Power Supply: A direct current supply that powers radios.

Private Line: Motorola's trademarked term for CTCSS

Quarter Wave: A short antenna typically seen on vehicles - about six inches on UHF, about 15-18 inches on high band, about 5-9 feet on low band.

Radio Tech: A frequently sought after individual who understands the inner workings, hidden mechanisms, and theory behind the operation of radio systems. Often called upon to build, fix, or install radio systems. Usually misunderstood, unappreciated, underpaid and overworked.

The radio shop: The place of business of the radio tech.

Repeater: A radio transceiver usually located at a high place that receives a signal on one frequency and transmits it as received on another frequency. By doing so, a low power portable radio can retransmit a signal over a larger area. The benefit is that people can carry smaller radios and communicate with one another over a wide geographical area, a city, a county, or a region.

Rubber Duck: A small, flexible, short, inefficient antenna used on hand held radios.

Squelch: The squelch control or circuits of a radio "squelch" or make quiet the noise a radio receives when a radio signal is not present on the radio channel. The radio is un-squelched when a signal is received.

Squelch Threshold: The signal level at which a receiver squelch is broken.

Simplex: two units communicating direct on the same frequency. See Direct.

Site: "The site" often refers to the location of something like a repeater.

STE = GE's implementation of reverse-burst, called squelch tail elemination

Stubby: A slang term for a small rubber duck antenna.

Talk Around: Same as direct or simplex except you are doing so on a repeater output frequency Comes from teh concept of "talking around" the repeater.

The hill: A slang expression referring to a high location which could even be a mountain! See "Site".

Tone: Refers to CTCSS and sometimes DCS.

Tone Decoder: A circuit that senses the proper tone (or tone pair if DTMF) and does something.

Tower: Antennas are mounted on towers.

Watt: The measure of output power for a radio transmitter.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.