C.T.S. Flashcards
Analog and Digital Signals
Analog - Analog is a method of transmitting information by a continuous but varying signal. (ex. like a dimmer light switch. Many possible positions in a dimmer light switch)
An analog waveform is a smooth flowing line alternating from a high level to a low level. A sine wave.
Digital - Digital is a method of storing or transmitting information by discrete, non-continuous impulses. (ex. like a standard light switch, on or off. 1 means on 0 means off)
A digital wave form is a series of squares with high and low voltage states.
Sampling Rate
How many times, per second, a digital sample is taken of the analog signal. (ex. A sample rate of 44.1 kHz is 44,100 samples taken every second. This technique is called Pulse Code Modulation PCM)
How many times, per second, a digital sample is taken of the analog signal. (ex. A sample rate of 44.1 kHz is 44,100 samples taken every second. This technique is called Pulse Code Modulation PCM)
Nyquist-Shannon Sampling Theorem
- An analog signal can be reconstructed if it is encoded using a sampling rate that is greater than twice the highest frequency sampled. (ex. Human hearing extends to 20kHz so the sampling rate for digital audio should be greater than 40 kHz)
Bit Depth
The number of bits used to describe a sampled voltage level. Also knows as quantization because it involves assigning a quantity to the signal being measured. Greater bit depth gives a more accurate representation of the sampled signal. As the number of bits increases, the number of possible states increases exponentially. A bit depth of 16 will have 65,536 possible states. 2 to the 16th power.
Bit Rate
The measurement of the quantity of information over time in a digital signal stream. The higher the bit rate, the better the signal quality. Quantified in bits per second or bps.
Compression
- A process that reduces very large files to smaller, manageable sizes. Compressed files discard unnecessary information, which reduces the size of digital files and makes them easier to transmit and store. This process is used extensively in computer applications, such as streaming audio or visual content over the Internet.
***Two Elements of a digital file
(Container and CODEC
CODEC (Coder/Decoder
An electronic device that converts analog signals, such as video and audio signals, into digital form and compresses them to conserve bandwidth on a transmission path. Uses an algorithm, or a set of procedures, to encode and decode file information.
Container -
The structure of a file where the data is stored. It defines how the data is arranged to increase performance and which codecs are used.
Lossless Compression
- A process that retains the original quality of a file after it has been compressed and decompressed. (ex. WinZip)
Lossy Compression
- A Lossy Compression form of compression that gives an approximation of the original data by eliminating redundant or unnecessary information.
Noise -
Any electrical signal present in a circuit other than the desired signal.
Network for Data and AV
***All networks have two main parts
nodes and connections.***
Node
Node - Any active device that sends and receives network data. (ex. Computer, mobile device, video server, projector)
Connections -
Connections - The physical means by which data travels from one node to another. (ex. RF, copper cabling, light). A passive device like a patch panel also falls into this category.
***Every device that connects to the network must have what
a network interface card (NIC) and associated MAC address.***
Network Interface Card (NIC)
- An interface that allows you to connect a device to a network.
MAC Address
The Actual hardware address, or number, of your NIC device. Uses a globally unique 48-bit number expressed as 6 groups of two hexadecimal numbers, separated by a hyphen or colon. The first part of the number indicates the manufacturer and the second part of the number is a serial number for the product or circuit component. Each NIC has its own associated MAC address.
Network Switch
Network Switch - Provides a physical connection between multiple devices. As each device connects the switch collects and stores its MAC address. Allows connected devices to the same switch to communicate directly with each other via Ethernet, using only MAC addresses to locate each other.
Unmanaged switches have no
no configuration options. Plug in a device and it connects.
Manages switches
- Allow the adjustment of port speeds, set up virtual local area networks (VLANs), configure quality of service, monitor traffic.
Router
- Forwards data between devices that are not directly physically connected. Marks the border between a local area network and a wide area network. When traffic leaves a local area network (travels beyond the switch) routers direct it until it reaches its final destination. When data reaches the router it examines the packet’s logical address (IP address) to determine the next destination
Gateway
- A router that connects a private network to outside networks. All data that travels to the internet must pass through a gateway. Routers below the gateway will forward packets destined for any device that can’t be found on the private network to the gateway. When traffic arrives from outside the private network, the gateway forwards it to the appropriate router below. Also translates data from one protocol to another. (ex. When data leaves a private network to travel across the Internet, a gateway translates it from a baseband to a broadband protocol.)
Server
- A piece of computer hardware or a program that runs on a computer alongside other programs that does nothing but provide services to dependent nodes
Thin Server
- A server that offers only one service.