Do I need CTCSS codes to receive?

[chas0039]

I have noticed that my GRE 800 identifies the CTCSS codes when it receives some analog frequencies. I was wondering if there is some sort of convention that says that certain types of transmissions need these codes to hear the transmission. On the 2 meter ham bands, these are used for repeaters, and the codes are needed for the repeater to hear my transmissions, but I don't enter any codes to hear signals from the repeater. It seems odd that the GRE would go to the trouble to identify these codes if, in fact, i didn't really need them to hear. Obviously, there is no transmitting on my part.

Do these need to be entered for listening to some types of stations?

Thanks

 

[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+)

You do not need the tones to receive any transmissions. If ytou have multiple agencies that use the same frequency, they will generally use different CTCSS/DCS tones/codes to keep the radios silent, and only pass audio for the respective agency.

 

[gewecke]

It's important to know what CTCSS tones are used if you want to block out other users on the same freq or unwanted interference even just to receive. otherwise no they are not needed.


73,
n9zas

 

[K9WG]

Also used by repeaters to block unwanted transmissions from distance stations. It is possible for a VHF transmission to hit a repeater in a different state several hundred miles away. CTCSS will keep the distant transmission from keying up the repeater (provided they are different CTCSS frequencies).

For what it's worth: Central Indiana has an amateur repeater that is utilized for state wide Skywarn. They use one CTCSS for normal operations and another for when Skywarn is active. I have each CTCSS programmed into different channels so I know when Skywarn has been activated.

 

[N8IAA]

It seems odd that the GRE would go to the trouble to identify these codes if, in fact, i didn't really need them to hear. Obviously, there is no transmitting on my part.

The scanner manufacturer has nothing to do with what CTCSS/DCS/NAC codes are attatched to whatever frequencies (other than allowing them to be heard on the transmission). The Radio Reference database that is on the SD card has the different codes attatched to the frequencies. The scanner just decodes what it is told to do
And, as others have stated, no you do not need them to hear the transmissions.
HTH,
Larry

 

[chas0039]

Thanks, makes sense.

 

[JStemann]

I make use of the CTCSS/DPL codes a lot in my scanners. One example...our local fire dept and one about 40 miles away use the same freq. I don't care what's going on 40 miles away. I programmed the tone for our local fire in, now I don't have the FD from 40 miles away bugging me.

Another example, I've got quite a bit of noise in my house, my vehicles and from some lights or something on the way to work. Used to be, I'd have to turn the squelch way up or lock out the freq completely, now with the ctcss programmed in, I can keep the squelch where it should be, and no more annoying noise.

I also programmed our local club repeater to transmit a tone, so I could avoid some computer noise in the house. No tone needed to access the repeater, but it's there if you want to use it on your receiver, but not required to hear.

Jeff.

 

[canav844]

Another example, I've got quite a bit of noise in my house, my vehicles and from some lights or something on the way to work. Used to be, I'd have to turn the squelch way up or lock out the freq completely, now with the ctcss programmed in, I can keep the squelch where it should be, and no more annoying noise.

I also programmed our local club repeater to transmit a tone, so I could avoid some computer noise in the house. No tone needed to access the repeater, but it's there if you want to use it on your receiver, but not required to hear.

Jeff.

I really wish the local amateur repeaters would pick on on this around me, for these reasons. I battle interference from neighbors houses (CFLs to TVs) so the standing RF level on 2m usually leaves me setting an RF squelch at S7, as if it's any lower I'm in a steady stream of static, followed by a burst of static every so often, because the ham repeaters ride on towers with other radios, and those other stations will trip the repeater, the quieting when the courtesy tones go, then back to static. With solar conditions the last month or so, there's a repeater about 150mi away on the same frequency, they've got tones, we don't bother them, they key up and we've got our local repeaters going (another repeater user has gotten the CW ID, I've only ever heard it as static) So they can be very helpful in that manner. Also when I travel, having a scanner search the ham bands, that shows the CTCSS, helps me quickly set my radio to whatever the active local repeater may be without needing to rely on a database full of "paper" repeaters

Getting back to scanning, I think GA still has in place a system (though it sounds they're moving off of it) where there's one frequency for the state patrol, and as you go from district to district (or maybe one per district and county to county), and the CTCSS changes instead of the frequency, in those cases if you want to know where you're listening to then knowing and having programmed in the tones could be critical. Checking the database it may have already been phased out, and it certainly is becoming less and less common, but being able to identify it can be very helpful.