CTCSS AND DCS AT THE SAME TIME?

[GMRSGuy]

I have a question about CTCSS and DCS and my ability to choose either one for my radios.

1) Can you use both at the same time? 2) If not, and you have both options, which would you use when your setup is for 8 different handhelds and three base stations that all communicate on the same GMRS frequency?

 

[ecps92]

You can not Transmit from ONE Radio, using both at the same time, but you can put in PL in One Channel and DPL in the next,,,

DPL is not as common in the bubble pack radios as folks default to the first "Privacy tone"

I have a question about CTCSS and DCS and my ability to choose either one for my radios.

1) Can you use both at the same time? 2) If not, and you have both options, which would you use when your setup is for 8 different handhelds and three base stations that all communicate on the same GMRS frequency?

 

[bharvey2]

Also not sure of the bubble pack radios but you could also use PL on Tx and DPL on Rx (or the reverse)

 

[GMRSGuy]

What would be the point of that? I am trying to get a deeper understanding of how this all works and why use one over the other. Also, I am not using bubble pack radios.

 

[KK6ZTE]

PL is more common than DPL, making DPL harder for someone to "break into" your conversation. What does this mean?

PL and DPL don't add any sort of privacy--all they do is prevent you from hearing anything else on the frequency besides radios with matching PL/DPL. This can be good or bad--it prevents you from hearing electronic noise like HDMI cables or LED lamps, but it can also prevent you from hearing legitimate users on the frequency and cause you to "walk" on them--which may be illegal depending on your frequency (not sure if part 95 requires that monitor before transmit like part 90 does).

If you're not worried about someone else hearing you, but you don't want to hear someone else (in case you're dealing with a jammer or something along the like, or simply want "quiet" radios the majority of the time) I suggest choosing a DPL code. The TX and RX codes will have to be the same unless you have a repeater to translate it (bharvey2's suggestion requires a repeater to translate the DPL into PL etc). You can only use one method of tone squelch (DPL or PL) at a time. Most of the time, a party trying to mess with you will simply scroll through the PL tones trying to get a match. Most don't even know what DPL is much less how to access it.

 

[GMRSGuy]

PL is more common than DPL, making DPL harder for someone to "break into" your conversation. What does this mean?

PL and DPL don't add any sort of privacy--all they do is prevent you from hearing anything else on the frequency besides radios with matching PL/DPL. This can be good or bad--it prevents you from hearing electronic noise like HDMI cables or LED lamps, but it can also prevent you from hearing legitimate users on the frequency and cause you to "walk" on them--which may be illegal depending on your frequency (not sure if part 95 requires that monitor before transmit like part 90 does).

If you're not worried about someone else hearing you, but you don't want to hear someone else (in case you're dealing with a jammer or something along the like, or simply want "quiet" radios the majority of the time) I suggest choosing a DPL code. The TX and RX codes will have to be the same unless you have a repeater to translate it (bharvey2's suggestion requires a repeater to translate the DPL into PL etc). You can only use one method of tone squelch (DPL or PL) at a time. Most of the time, a party trying to mess with you will simply scroll through the PL tones trying to get a match. Most don't even know what DPL is much less how to access it.

OK... I am clear they are NOT for privacy. It is more for blocking others out. That is great. So, what you are saying is using the DCS or DPL as you reference, this might deter some amateurs in the area from breaking into the conversations because it is not as widely known at the CTCSS PL tones correct? Outside of this, what is the purpose for having two ways of doing this? One has to have a feature over the other or a reason to use over the other. It doesnt make sense to me that they both do the exact same things exactly, if that was the case the second one DPL would not be needed and a feature on the radio. So, can someone get a bit deeper on 1) what are the main differences between the two, 2) why use one over the other (other than what has already been stated), and 3) reasons why you would CTS on one frequency but you might use DPL on another?

I am just trying to get a thorough understanding of these two items. Thanks so much!

 

[bharvey2]

PL is more common than DPL, making DPL harder for someone to "break into" your conversation. What does this mean?

PL and DPL don't add any sort of privacy--all they do is prevent you from hearing anything else on the frequency besides radios with matching PL/DPL. This can be good or bad--it prevents you from hearing electronic noise like HDMI cables or LED lamps, but it can also prevent you from hearing legitimate users on the frequency and cause you to "walk" on them--which may be illegal depending on your frequency (not sure if part 95 requires that monitor before transmit like part 90 does).

If you're not worried about someone else hearing you, but you don't want to hear someone else (in case you're dealing with a jammer or something along the like, or simply want "quiet" radios the majority of the time) I suggest choosing a DPL code. The TX and RX codes will have to be the same unless you have a repeater to translate it (bharvey2's suggestion requires a repeater to translate the DPL into PL etc). You can only use one method of tone squelch (DPL or PL) at a time. Most of the time, a party trying to mess with you will simply scroll through the PL tones trying to get a match. Most don't even know what DPL is much less how to access it.

Good point about my comment. I should have pointed out that my suggestion only works with repeaters. There are a few GMRS repeaters in my area and DPL is used on the repeater inputs to minimize interference from the lower cost bubble pack radios that don't have DPL capability.

 

[KK6ZTE]

Good point about my comment. I should have pointed out that my suggestion only works with repeaters. There are a few GMRS repeaters in my area and DPL is used on the repeater inputs to minimize interference from the lower cost bubble pack radios that don't have DPL capability.

Yes, DPL is a good "filter" mechanism to keep out the lowest common denominator. We have a couple lids in our area that would benefit from a switch to DPL

 

[GMRSGuy]

Good point about my comment. I should have pointed out that my suggestion only works with repeaters. There are a few GMRS repeaters in my area and DPL is used on the repeater inputs to minimize interference from the lower cost bubble pack radios that don't have DPL capability.

So, using DPL has two benefits if what I am reading is correct. 1) keeping others out in my area because its pretty well unknown to the real amateurs of bubble pack radios etc and 2) it helps decrease noise on a repeater level for those radios that use repeaters but do not have DPL built into the radio? Am I understanding that correctly?

 

[ecps92]

Wasn't even thinking the OP was referencing PL TX and DPL RX or vice-vesa, good catch

Also not sure of the bubble pack radios but you could also use PL on Tx and DPL on Rx (or the reverse)

 

[bharvey2]

Wasn't even thinking the OP was referencing PL TX and DPL RX or vice-vesa, good catch

Looking back at the original post, since there is no mention of a repeater, I could have been wrong. I made an assumption. You know where that can get you.

 

[KK6ZTE]

So, using DPL has two benefits if what I am reading is correct. 1) keeping others out in my area because its pretty well unknown to the real amateurs of bubble pack radios etc and 2) it helps decrease noise on a repeater level for those radios that use repeaters but do not have DPL built into the radio? Am I understanding that correctly?

I think the reason they are doing it that way is to keep users who are using the "input" channels (467.xxxx) in a simplex fashion (radio to radio). They'll never hear the repeater but the repeater would be hearing them and repeating whatever they transmit.

 

[ecps92]

Some of us, also used it to give a person his/her own input tone, then when no longer welcome easier to disable em

I think the reason they are doing it that way is to keep users who are using the "input" channels (467.xxxx) in a simplex fashion (radio to radio). They'll never hear the repeater but the repeater would be hearing them and repeating whatever they transmit.

 

[kayn1n32008]

One advantage of DPL, is that even eliminating the complementary codes, there are more DPL codes than PL tones.

PL tones are a continuous sub audible tone that is modulated on your carrier.

DPL is a repeating 13(?) bit code that is continuously modulated on your carrier. Both do the same thing, but in different ways.

 

[techman210]

PL and DPL came about from the commercial, not amateur world.

Originally, PL had 32 tones. That meant 32 companies could use a given frequency without one company hearing traffic from the other. In large metropolitan areas where radios are on high hilltops, that could be a problem.

Also, community repeaters were created, and to have more than 32 tones/codes would actually allow you to have more than 32 customers on that repeater.

So that spurred the growth and creation of DPL and its other random trademark names.

 

[chief21]

Techman is on point.

And another reason is that the radio manufacturers always need at least one new "feature" that can help sell more radios!

 

[bpendleton]

I think the reason they are doing it that way is to keep users who are using the "input" channels (467.xxxx) in a simplex fashion (radio to radio). They'll never hear the repeater but the repeater would be hearing them and repeating whatever they transmit.

It's not allowed to use the 467.XXX repeater inputs for simplex, and, at least for any actually compliant part95 radio I've seen, pretty difficult to do accidentally. Does this actually happen in the wild?

 

[KK6ZTE]

It's not allowed to use the 467.XXX repeater inputs for simplex, and, at least for any actually compliant part95 radio I've seen, pretty difficult to do accidentally. Does this actually happen in the wild?

Since when does everyone follow the rules? Lots and lots of unapproved radios out there on "quiet" channels that are inputs.

462/467 GMRS is pretty close to the med channels around 463/468 and we've seen users of "GMRS" radios end up there.

I think we've gone way past the original point of discussion so I won't elaborate too much further.

 

[RKG]

Not to pile on, but:

1) I am aware of no subscriber radio that has the capacity to transmit both a PL and DPL at the same time.

2). Even were that not so, one would likely interfere with the other, yielding either tone roll-off or tone falsing. PL is a continuous low level sine wave modulation at the specified frequency. DPL is essentially a continuous low level square wave consisting of error bits plus a four digit octal code (octal 4 plus octal DPL code), at a frequency of about 130 Hz.

 

[rescue161]

I have one of my GMRS repeaters set up with a split tone. You have to transmit DCS to activate the repeater and the repeater transmits out a PL. I used it that way to confuse the bubble-packers and to cut down on the riff-raff. I made it's use public, so anyone with a license can use it now. I am going to omit the PL and go straight DCS TX and RX. I just need to make some time to get out to the site to program.