CAT Signal Transmission and Central Station Monitoring 1 — Questions and Answers
Question 1: Which communication format is most widely used to transmit alarm signals from a control panel to a central monitoring station via telephone lines?
- FSK tone burst only
- Contact ID (Correct answer)
- SIA DC-09 IP
- DTMF handshake only
Correct answer: Contact ID
Contact ID is the industry-standard digital communication format adopted by virtually all alarm manufacturers for transmitting event data over POTS lines.
Question 2: What does the term 'polling' mean in the context of alarm signal transmission?
- Counting the number of active zones in a panel
- The central station periodically querying a communicator to verify it is online (Correct answer)
- Testing alarm panel batteries under load
- Manually triggering zones to confirm sensor operation
Correct answer: The central station periodically querying a communicator to verify it is online
Polling is the process by which the central station receiver periodically sends a check-in request to the field communicator to confirm the communication path is active.
Question 3: Why is a standard POTS (Plain Old Telephone Service) telephone line considered a vulnerability in alarm signal transmission?
- It transmits signals too slowly for modern receivers
- The line can be physically cut, defeating communication before an alarm is sent (Correct answer)
- It is incompatible with Contact ID protocol
- It requires a dedicated circuit that increases installation cost significantly
Correct answer: The line can be physically cut, defeating communication before an alarm is sent
A POTS line can be cut at an accessible point outside the premises, preventing the alarm signal from reaching the central station — a well-known defeat method.
Question 4: What is 'split reporting' in alarm signal transmission configuration?
- Dividing alarm signals between two receivers at the same central station
- Routing burglar alarm signals to one central station and fire alarm signals to a separate central station (Correct answer)
- Splitting a single phone line between voice and data simultaneously
- Using two independent control panels to cover one protected premises
Correct answer: Routing burglar alarm signals to one central station and fire alarm signals to a separate central station
Split reporting directs different alarm types (e.g., fire vs. burglary) to separate central stations, which is common when fire monitoring requires a UL-listed fire-specific central station.
Question 5: What is the purpose of a 'handshake' in the Contact ID digital communication protocol?
- To encrypt the signal payload before it is transmitted
- To confirm the central station receiver has acknowledged and accepted the transmitted message (Correct answer)
- To test the telephone line for noise and signal quality
- To establish a live voice channel between the panel and the monitoring operator
Correct answer: To confirm the central station receiver has acknowledged and accepted the transmitted message
The handshake is the central station receiver's acknowledgment tone sent back to the DACT, confirming the message was received correctly and ending the transmission.
Question 6: What is 'supervision' in the context of alarm signal transmission?
- Monitoring zone wiring continuity for open or short circuit conditions
- Periodic check-in signals between a communicator and the central station to verify the communication path is intact (Correct answer)
- The process of assigning zone descriptors and labels during programming
- Central station operators viewing live video feeds from the protected premises
Correct answer: Periodic check-in signals between a communicator and the central station to verify the communication path is intact
Transmission supervision refers to scheduled check-in signals (heartbeats) sent by the communicator to the central station so loss of the path can be detected and reported.
Question 7: What is the primary advantage of using cellular communication over POTS for alarm signal transmission?
- Lower monthly recurring monitoring service fees
- Significantly faster signal delivery speed to the central station
- Resistance to line-cut attacks since there is no physical wire to defeat (Correct answer)
- Better backward compatibility with legacy control panel hardware
Correct answer: Resistance to line-cut attacks since there is no physical wire to defeat
Cellular communicators transmit over the wireless network, eliminating the physical telephone wire that an intruder could cut to defeat a POTS-based communicator.
CAT Signal Transmission and Central Station Monitoring 1
Which communication format is most widely used to transmit alarm signals from a control panel to a central monitoring station via telephone lines?