What is better to use DTCS or CT codes?

[Mrsig]

What is better to use DTCS or CT codes? On a repeater & radio.

[Socalgmrs]

Doesn’t matter at all.  Some people even mix them up.  

[Lscott]

My personal guess would be DTCS since it's a series of digital numbers sent over the air. The attached paper describes in some detail how the system works. With tones it all depends on the quality of the TX and RX radios. A few have commented that radios with low levels of deviation have failed to access some repeaters. Also there are cases where ding-dongs using something like DMR, against the rules on GMRS, have caused false triggering of the CTCSS squelch function to turn off the audio mute.

DPL _ DCS Squelch System.pdf

[Mrsig]

Thanks guys. My Repeater is coming today.

[WRUE951]

CTCSS is older and more prone to spurious noise opening the squelch - weather or ambient. Additionally, there are relatively few usable tones. DCS is newer was was designed to address those shortcomings.   Both came out of Motorola, who initially was one of the only manufacturers of radios with enough frequency stability to use DCS (though others caught up quickly). Even today, some Baofeng as they age have trouble with a DCS system. Also, many older radios can't use DCS at all, and a few transitional models needed modules to enable it (usually you'd swap our the CTCSS module to a dual mode module).   So, yes, DCS is better, but CTCSS more compatible.

[dosw]

This is a topic you could search for hours on and not come up with a clearly definitive answer. In fact, there's almost no argument, even. The advantages and disadvantages of each are so minor people don't really seem to be all that passionate about it.

 

CTCSS will behave with older equipment that doesn't support DCS. But who are we protecting? There aren't a lot of people operating 20 year old blister pack GMRS radios lacking DCS support on repeaters. Both are subaudable tones or sequences that have to be filtered out by the radio's high pass filter. Both have different reasons for behaving a little oddly at fringe-reception areas. DCS *may* take a little longer for the sequence to be transmitted completely enough for a radio to open squelch, but we're talking tenths of a second at most. CTCSS may be a little more crowded (you may have a slightly harder time finding a channel and tone pair that isn't in use).

 

But the fact that we have both systems really is a product of the evolution of marketing bullet points from vendors.  One or more vendors claimed they had a new and improved system, and they pushed it to the point that it gained adoption. But the fact that DCS and CTCSS have continued to co-exist for decades, filling the exact same purpose, without a clear winner pushing the other out of the way kind of indicates there's not a clear winner.