CTCSS stands for Continuous Tone Coded Squelch System, it is the generic abbreviation and is used to minimize co-channel interference.
Below is the terminology used by different commercial companies for CTCSS:
PL is the Motorola Abbreviation for "Private Line".
QC is the RCA abbreviation for "Quiet Channel".
CG is the General Electric abbreviation for "Channel Guard".
CTCSS is often referred to as a
"PL" tone by many users.
Many repeaters require the use of a PL tone to access the repeater.
The frequency that a user transmits to access a repeater is the Repeater CTCSS Encode Frequency.
The frequency that the repeater transmits to the user is the Repeater Decode Frequency.
Deviation of a transmitted tone should be a maximum of 500Hz.
Contrary to popular belief, the requirement of a PL tone to access a repeater does NOT mean it is closed. A PL is frequently used to preclude interference in high RF environments and lessen what is called kerchunking (unnecessary keying of the repeater). Some repeaters may also generate a PL tone on the repeater output so that repeater users who are equipped with a radio capable of decoding PL will not hear other interference sources on the channel that would otherwise open the squelch on the user's radio.
It is up to the owner / trustee of the repeater to decide whether or not to make public the PL tone for a particular repeater. MetroCor follows the wishes of the owner / trustee in publishing the PL code only when so requested.
MetroCor strongly recommends the use of PL on repeaters' receivers. PL is a minor inconvenience when you consider how many potential problems it can eliminate. The use of PL may be required for a coordination to be granted if conditions so warrant, such as proximity to a co-channel repeater, or in an area where band openings frequently aggravate co-channel interference problems.
MetroCor hopes that repeater owners / trustees in a given area will standardize on a particular PL tone and incorporate it into their operational plans. The reason for this is to make it easier for users to operate the local repeaters in an area, as some older radios are only capable of a single PL tone as compared to modern radios which can have PL tones selected on a per-channel basis.
Today most radios have encode PL devices. Some radios have both, encode and decode. If anyone needs a PL board for their radios they can check with the radio manufacturer and see if the tone boards are available. If they are not there are third party companies that manufacture PL units that fit into most models of radios. If you do not feel comfortable in installing a PL in your radio ask someone at your local radio club or contact any 2-way radio repair shop and they will be able to assist you.
The following chart showing each PL tone's two-character alphanumeric designator and the corresponding tone frequency in Hertz.
|Code||Tone Freq.||Code||Tone Freq.||Code||Tone Freq.|
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