A lot depends on the performance of the tone decoder you use. I have a couple of repeaters using Zetron 38A controllers that detect the tone way down in the noise, and one of them is operating with the squelch open so it is only controlled by the tone. It will stay keyed reliably with no discernible voice coming through, just sounds like open squelch noise. But in fact there is a weak signal there transmitting the correct tone. The only problem that I have with that is the long open squelch burst at the end of each transmission.
So, depending on your tone detector performance, you will probably get reliable operation down into the noise with the tone detector only controlling your repeater. 73 - Jim W5ZIT -----Original Message----- From: [EMAIL PROTECTED] To: [email protected] Sent: Fri, 23 Feb 2007 8:05 AM Subject: [Repeater-Builder] Tone squelch vs. carrier squelch Ok, I know all the usual reasons for using input tones on a repeater, but I have more of a theoretical performance question. Again, I'm putting together a portable VHF repeater out of a pair of Icom mobiles (IC-F121) for search-and-rescue use. Since it's for temporary, emergency use, my primary concern is weak-signal performance, particularly being able to hear someone out in the field with a 5W handheld and a rubber duck. Here's my question: For the best chance of allowing my repeater to hear that weak signal, am I better off using an input tone and turning the receiver squelch way down (perhaps even all the way), or using no input tone and plain old carrier squelch (at a higher level)? I'll almost certainly end up using a receive tone on this thing anyway just to minimize interference potential, but it seems to me that doing so might help improve my "ears" as well. Comments? Brian K9JVA ________________________________________________________________________ Check Out the new free AIM(R) Mail -- 2 GB of storage and industry-leading spam and email virus protection.
