PRO-164 CT Search?

[dallascowboys]

I have a radio shack pro 164 I have the frequency of 155.145 when this appears I also have C T 179.9 Search, what is CT and why is it telling me to search? can someone please help me on this

Thank You

 

[Rick345]

CT is shorthand for Continuous Tone, a subaudible tone transmitted through the repeater by mobile rigs in order to key up the repeater. Its a way to ensure the PS personnel are talking through their local repeater and not coincidentally keying up other repeaters on the same frequency. 155 MHz is often line of site, but sometimes conditions allow radio waves on VHF to carry for long distances. I live in Mobile and I can normally talk to hams in Mobile and Baldwin counties on the 146.82 MHz repeater however, when conditions are favorable for DX on 2 meters AKA VHF I've talked to hams in Mexico City on the 146.82 machine. DX is fun for hams, but could be disastrous for PS communications. Without the CT frequency the 155.145 repeater could accidently be keyed up by some other agency in say Miami on 155.145.

However, I don't own a pro 165 and I'm not sure why it is asking to to search. If you can hear Dothan on 155.145 I wouldn't worry about the search thing.

 

[kcoleman]

I have a radio shack pro 164 I have the frequency of 155.145 when this appears I also have C T 179.9 Search, what is CT and why is it telling me to search? can someone please help me on this

The CT code or CTCSS (Continuous Tone-Coded Squelch System): "It is a use of sub-audible tones that are transmitted along with the speech portion of the transmission which allows more than one agency (or fleet) to use the same radio frequency without causing undue interference to another agency on the that frequency. Receivers for agency XYZ are set to only open their audio squelch when the proper sub-audible frequency tone is part of the transmission."

For example; if Dothan police are using 155.145 as a car-car channel and Houston county uses the same frequency as sheriff tac channel, then when one agency talks the other agency would hear it. With the CT codes, each agency can have a separate code but still use the same frequency without interference from each other.

When you programmed 155.145 into the radio the receive mode was set to CT but no tone code was entered, then when a transmission occurs on that frequency the radio goes into CT Tone Search mode, in your case it has decoded the tone as 179.9. When in the search mode and while a transmission is in progress and a code appears, press the ENT key and it will save that tone code to the frequency.

This also works the same way for DCS codes.

Hope that helps.
Keith,

 

[dallascowboys]

Pro 164

Thanks for the help, I understand now