Alarm Systems and Satellite Dish Characteristics

Posted on Mar 8, 2025 in Physics

Components of an Alarm System

An alarm system comprises several key elements working together:

Network of Detectors: Operates 24/7, monitored for alerts. Key points are prioritized, with nighttime operation often being more critical.
Control Unit: Analyzes information from detectors and triggers appropriate actions. Sophisticated systems may use computers for advanced information processing.
Signaling Network: Alerts occupants and authorities. Alarms can be audible (sirens, bells) or silent (e.g., triggering photographic fire alarms). It has its own power system for continued operation during power failures.
Power Supply: Provides continuous operation. Two main scenarios exist:
1. Facilities with continuous power use batteries for backup.
2. Alarms designed for infrequent use rely on batteries activated only during an alarm event.
Distribution Network: Connects all electrical components of the system.

Various detector types exist, including:

Example Applications:

Office: An ion detector is suitable due to its broad coverage and rapid response.
Kitchen: A thermal detector is ideal, triggering quickly in response to high heat.

Key characteristics of satellite dishes include:

Gain: Maximum gain, measured in dB, is achieved with an antenna optimized for maximum radiation. Gain varies with location and orientation.
Bandwidth: The range of frequencies the antenna operates within.
Impedance (Z): Resistance to current flow, dependent on inductive and resistive components.
Frequency Response: Represented graphically, showing gain (dB) versus frequency.
Directivity: The degree to which radiation is concentrated at a point.
Beamwidth: The angle of the main lobe’s widening.
Front-to-Back Ratio: The relationship (in dB) between gain in the intended direction and the opposite direction.
Radiation Pattern: A graphical depiction of antenna radiation in different directions, showing lobes:
1. Main Lobe: Represents the majority of the signal received or transmitted.
2. Back Lobe: Represents scattered radiation opposite the main lobe.
3. Side Lobes: Represent radiation to the sides of the main lobe.

Consists of two equal-length conductors, each connected to the corresponding wiring. Two types exist: half-wave dipole and folded half-wave dipole.

Reflectors: Placed behind the dipole, opposite the signal reception direction, to increase gain.
Directors: Mounted in front of the dipole, in the signal transmission direction, to increase directivity.

Typical Values:

Offset Antenna: The focus is shifted downwards. The outdoor unit is supported by a single bracket, minimizing shadow area in reception.
Prime Focus Antenna: The focus is located at the parabolic reflector. The LNB is supported by three rings. The LNB and its power supply are separate, and supports can create shadows, affecting signal reception.

LNB (Low-Noise Block Converter): Converts very high-frequency signals to intermediate frequencies.

IF (Intermediate Frequency): Frequencies that can be easily distributed throughout the installation.

RITI (Recinto de Instalaciones de Telecomunicación Inferior): Enclosure for the installation of telephone and telecommunication cables.
RITS (Recinto de Instalaciones de Telecomunicación Superior): Enclosure for equipment and the collection of TV and radio signals.
Network Termination Records: Placed in the housing, these can be built-in or surface-mounted. Pipelines must enter these records.
Secondary Records (Child Records): Used for wiring passage and splitters for the network within a building. These records are located in accessible areas.
Junction Boxes (Registration Step): Auxiliary boxes installed every 15m between secondary records and network termination points.