PL or DPL?
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CTCSS and DCS
PL ("Private Line"- a trademark of Motorola), CG ("Channel Guard" - a trademark of GE), or CTCSS (Continuous Tone-Coded Squelch System) is much more widely available, particularly in older radios and easier to install a card to perform its function. Most amateur radios (HAM) have this feature.
DPL ("Digital Private Line" - a trademark of Motorola), DCG ("Digital Channel Guard" - a trademark of GE), or DCS (Digital-Coded Squelch) is newer and much less readily available. For this reason, technically it is a more secure way to encode transmissions to filter out unauthorized users on a repeater system.
Both CTCSS and DCS are types of CSQ (carrier squelch). Neither one prevents someone from hearing the transmissions. They are more like filters for the specific users using them and codes to turn on a repeater for incoming transmissions (in laymen's terms).
See more information here: http://encyclopedia.thefreedictionary.com/Squelch
PL ("Private Line"- a trademark of Motorola), CG ("Channel Guard" - a trademark of GE), or CTCSS (Continuous Tone-Coded Squelch System) is much more widely available, particularly in older radios and easier to install a card to perform its function. Most amateur radios (HAM) have this feature.
DPL ("Digital Private Line" - a trademark of Motorola), DCG ("Digital Channel Guard" - a trademark of GE), or DCS (Digital-Coded Squelch) is newer and much less readily available. For this reason, technically it is a more secure way to encode transmissions to filter out unauthorized users on a repeater system.
Both CTCSS and DCS are types of CSQ (carrier squelch). Neither one prevents someone from hearing the transmissions. They are more like filters for the specific users using them and codes to turn on a repeater for incoming transmissions (in laymen's terms).
See more information here: http://encyclopedia.thefreedictionary.com/Squelch
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Also, from the Wiki:
"[DCS] allows for over 100 possible fleet codes to be used. This gives it an advantage over the CTCSS tones in that there are more possible codes to use; however, it does use more bandwidth and can be affected by voice tones below 300 Hz if not properly filtered by the radio circuitry."
There is lots more information about DCS here:
http://www.open.org/blenderm/dcs.html
"[DCS] allows for over 100 possible fleet codes to be used. This gives it an advantage over the CTCSS tones in that there are more possible codes to use; however, it does use more bandwidth and can be affected by voice tones below 300 Hz if not properly filtered by the radio circuitry."
There is lots more information about DCS here:
http://www.open.org/blenderm/dcs.html
Hi all,
Just to clarify and avoid confusion;
"Both CTCSS and DCS are types of CSQ (carrier squelch)."
Not at all! Carrier Squelch (CS) uses the presence of the carrier which quiets the noise to open the squelch. It employs a noise gate that amplifies receiver noise and rectifies the AC waveform into a DC control voltage which holds the gate closed, squelch. When the carrier quiets the noise the resulting voltage drops below a preset threshold set by the squelch control opening the gate.
"Neither one prevents someone from hearing the transmissions."
True, when the receiver uses carrier squelch the presence of a tone or digital code matters not.
"They are more like filters for the specific users using them and codes to turn on a repeater for incoming transmissions (in laymen's terms).
Yes, the presence of a subaudable tone (PL) opens the squelch gate much the same as the noise gate does with CS. DSQ (DPL) opens the gate like a key in a lock the same way, the tone or digital code must match the preset.
"Wrath of Conrail"? (;->)
Just to clarify and avoid confusion;
"Both CTCSS and DCS are types of CSQ (carrier squelch)."
Not at all! Carrier Squelch (CS) uses the presence of the carrier which quiets the noise to open the squelch. It employs a noise gate that amplifies receiver noise and rectifies the AC waveform into a DC control voltage which holds the gate closed, squelch. When the carrier quiets the noise the resulting voltage drops below a preset threshold set by the squelch control opening the gate.
"Neither one prevents someone from hearing the transmissions."
True, when the receiver uses carrier squelch the presence of a tone or digital code matters not.
"They are more like filters for the specific users using them and codes to turn on a repeater for incoming transmissions (in laymen's terms).
Yes, the presence of a subaudable tone (PL) opens the squelch gate much the same as the noise gate does with CS. DSQ (DPL) opens the gate like a key in a lock the same way, the tone or digital code must match the preset.
"Wrath of Conrail"? (;->)
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2112 said:
PL is Motorola's name for CTCSS (EIA generic term)
DPL is Motorola's name for CDCSS (EIA generic term)
Uses more bandwidth? I guess that is technically true since the CDCSS is modulated at 1 kHz while CTCSS is 500-750 Hz, but when taken into account both are used with voice signals that are as much as 5.0 kHz, it seems to be a moot point. Neither will be the dominant bandwidth hog on the signal.
CDCSS does seem to track better into the noise when using quality equipment. That is an advantage.
There is a standard turn-off code on CDCSS to mute squelch tails while there are at least three turn-off codes on CTCSS (actually, two formats plus 'none'). Note that true PL itself only uses one format - Motorola's.
There are up to 112 CDCSS codes while there are as many as 50 CTCSS tones. As was mentioned, that is an advantage (less chance of duplication). Although, only about 38 CTCSS tones work reliably - without falsing adjacent tones - on many receivers.
CTCSS is available on more radio models than CDCSS. (including more scanners)
CDCSS requires a true FM transmitter. It won't work on a PM transmitter well, if at all.
Neither is superior in all cases.
Oh, CTCSS is more likely to be affected by voice tones below 300 Hz since voice is tone, not digital, and since the tones come much closer to 300 Hz than the digital code speed - by a factor of about two. Each mode requires voice filtering.
Joe M.
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