# Terms
## Check
Number of words or word equivalents in the text portion of a message.
Used to ensure a message was received entirely.
Verbal.
## CTCSS
Stands for "Continuous Tone-Coded Squelch System."
A sub-audible tone transmitted along with voice to a repeater to open up the squelch of a receiver. It's like a key for using a repeater.
## DCS
Similar to CTCSS, but uses digital codes. More frequently used in metropolitan areas.
## Squelch
Used to avoid transmitting static.
# Repeaters
## Troubleshooting
If you can't transmit to a receiver, it could be:
1. Lack of proper CTCSS or DCS tone
2. Incorrect offset for transmission (receivers use one frequency to transmit, one to receive)
3. May also need a "color code" to get access.
# Test Practice
## Technician
Q. When can you break FCC rules?
A. Trick question. Never. "You can transmit under emergencies" is an FCC rule.