DCS CTCSS question

[Drewstang]

Since this is the only radio forum I'm registered on, I figured asking here would be my best bet. First off, I'm not licensed. If this is a problem then I'm sorry. I'm not going to pay for a license for something I don't use all the time. The fire department sees me fit to transmit under their license during emergencies on our county wide system, that should be good enough.

Now that's out of the way, I have a question reguarding the DCS and CTCSS on my Puxing radios. A group of friends and I are involved in airsoft some what professionally. We have a very large game coming up at the end of the month and I would like to program our radios so we can maintain constant coms while at this large Area of Operations without using the usual GMRS/FRS sub freqs. What would be the best method to use and can someone give me a simple explaination of how each works? Also a brief explaination on how to program the radios so they will "speak" to each other, but receive on a GMRS / FRS channel. All radios are UHF and programmed for GMRS and FRS with the propper power settings.

Thanks RR.

 

[kayn1n32008]

Wirelessly posted (Mozilla/5.0 (BlackBerry; U; BlackBerry 9780; en-US) AppleWebKit/534.8+ (KHTML, like Gecko) Version/6.0.0.600 Mobile Safari/534.8+)

Unless you use ham band (with proper license of course) you are SOL for anything other than FRS, GMRS requires a license as does ANY other frequency in the UHF band, except for FRS. The ONLY other options would be MURS on VHF or childrens radios in the 49Mhz area. Every thing else requires licensing. Having said that, I suggest you duck and cover cause the SAPS will be here any time...

 

[KG4INW]

I don't quite understand what you're asking regarding CTCSS (a.k.a PL) and DCS (a.k.a. DPL) tones. Are you trying to use tones that aren't available in bubblepacks? Really all the tones do (either PL or DPL) is quiet your receiver so it'll only unsquelch when it receives the programmed tone. Anyone else on the frequency will still hear you. Why use one over the other? I'm still not sure, but there must be advantages/disadvantages to both schemes.

 

[Drewstang]

Yes and no. Basically I want to setup these Puxings on GMRS / FRS channels, reduce the power so they are legal, and make the radios "talk" to only each other but not interfer with other GMRS / FRS users on the same freq's.

 

[Ed_Seedhouse]

Yes and no. Basically I want to setup these Puxings on GMRS / FRS channels, reduce the power so they are legal, and make the radios "talk" to only each other but not interfer with other GMRS / FRS users on the same freq's.

Well, you can't do it that way. Anyone with a radio with no tone set and within range will hear you no matter what tone you have set. And even if you both use different tones only one of you can use the radio at a time on the same frequency without interfering with each other, unless they are far enough apart for FM's capture effect to come into play. But in that case it won't matter whether or not you are using tones.

 

[zz0468]

edit: never mind.

 

[robertmac]

What has this to do with Ham Radio

Wouldn't it be better posted in GMSR/FRS/MURs threads?

 

[Drewstang]

I figured this was a little more technical than most threads in that section since I'm actually programming the portables instead of selecting options in the menu.

 

[elk2370bruce]

Most FRS handheld radios give you the opportunity to enter a PL to cut down on othr user chatter. Check the user manual for your radios. Obviously, you need to make sure that they each are set the same.

 

[jeffmarshall911]

Regarding frequency and tone, a frequency is the spectrum space that the radio is transmitting and receiving on. Any radio set to the same frequency can communicate to another radio with the same frequency. Think of your car stereo; the radio station transmits on 107.9 Mhz and you set your stereo on 107.9 Mhz to hear it.

A manufacturer came up with the process of introducing a sub-audible tone (you cannot hear it) that gets sent with the transmission. Another radio without a tone programmed can still hear the transmission (also a radio that is in 'monitor' or some other ‘open’ mode can hear it). Another radio with a different tone programmed will not recognize the tone and will remain quiet. Motorola calls this Private Line (PL) but it's technically Continuous Tone-Coded Squelch System (CTCSS). The idea was to allow different users to share the same frequency space with minimal interference. DCS is similar but is a digital code being transmitted rather than a sound.

The hazards have already been pointed out:
- A radio without a tone programmed will receive all transmissions on the frequency that it’s programmed to receive regardless of tone programmed by the transmitting radio.
- A radio with a tone programmed will not be heard by a radio with the same frequency but different tone programmed.
- Radios with the same frequency but different tones programmed, if transmitting at the same time and near enough to each other can sound garbled to the receiver (i.e. interference).

A simple Google search should help relating to the frequencies to GMRS/FRS “channels” and then tones to “numbers” to program into your radio. Each manufacturer *could* have different tones for their own nomenclature (i.e. Motorola tone '1' may not be Radio Shack tone '1'). In your case, testing will be necessary if you are trying to assure that your ‘programmable’ radios will either work or be silent to other’s bubble pack radios.

HTH,

/Jeff

 

[kb2vxa]

The guys here have things in hand but one slipped their grip, a most important one.

"The fire department sees me fit to transmit under their license during emergencies on our county wide system, that should be good enough."

Good enough NOT. Unless you're using one of their radios or another FCC certified for Part 90 operation that's clearly illegal.

"Now that's out of the way, I have a question reguarding the DCS and CTCSS on my Puxing radios."

Another fly in the ointment, for use outside the ham bands they're illegal. Bottom line here is using equipment certified for the frequencies you intend to use is the only legal way of doing it.

 

[KB7MIB]

Wirelessly posted (Mozilla/5.0 (X11; Linux i686; U; en-US) Gecko/20081217 Vision-Browser/8.1 301x200 LG VN530)

I think the only way to do what you want to do, legally *and* without interferring with others and being interferred with by others, is to use Nextel PTT or something similar (whatever is replacing Nextel).

 

[michaeldim]

As it has been repeated, CTCSS and DCS does not, in any way, prevent eavesdropping.

However, there is a way to secure your communications for your Airsoft if necessary.

The MURS band permits scrambling of analog signals. Now in MURS you are restricted to 2 watts output power, bear in mind, but it should still be sufficient. You will need some radios that support scrambling first though, but it is legal to use in MURS.

It won't be as secure as, say, encrypted P25, but it'll make eavesdropping by the rival team extremely unlikely.

 

[sacluded]

One requirement of FRS is that the antenna has to be fixed, it can't be removable. I'm pretty sure your Chinese ham radios have removable antennas. MURS really is the best option for you.