Base Band

New posts about Base Band.

Earth Station

New posts about Earth Station.

Computer Networking

All posts about Computer Networking.

Product Review

New product reviews.

What is Bitrate, CBR, VBR ?

What is the bitrate?
In telecommunications and computing, bit rate (sometimes written bitrate) is the number of bits that are conveyed or processed per unit of time.

Bit is the unit of information.  Remember that 1 byte consists of 8 bits. Video data rates are given in bits per second. The data rate for a video file is the bitrate. So a data rate specification for video content that runs at 1 megabyte per second would be given as a bitrate of 8 megabits per second (8 mbps). The bitrate for an HD Blu-ray video is typically in the range of 20 mbps, standard-definition DVD is usually 6 mbps, high-quality web video often runs at about 2 mbps, and video for phones is typically given in the kilobits (kbps).


Understanding bitrate in video files
It’s important to understand how the bitrate control corresponds to video quality and the file size. At the same bitrate, video in a newer codec such as H.264 will look substantially better than an older codec like H.263. Another consideration is that variable bitrate (VBR) encoding will produce better image quality than constant bitrate (CBR) in most applications.

What is Modulation ? AM, FM and PM.


Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted.

In telecommunications, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal. Modulation of a sine waveform transforms a base-band message signal into a pass-band signal.

A modulator is a device that performs modulation. A demodulator (sometimes detector or demod) is a device that performs demodulation, the inverse of modulation.  

A modem (from modulator–demodulator) can perform both operations.


Amplitude Modulation (AM)
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to the waveform being transmitted.



Figure: Amplitude Modulation 


Frequency Modulation (FM)
In telecommunications and signal processing, frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. 

Frequency modulation is widely used for FM radio broadcasting. It is also used in telemetry, radar, seismic prospecting. In radio transmission, an advantage of frequency modulation is that it has a larger signal-to-noise ratio and therefore rejects radio frequency interference better than an equal power amplitude modulation (AM) signal. For this reason, most music is broadcast over FM radio.




Figure: Frequency Modulation 



Phase Modulation (PM)
Phase modulation (PM) is a modulation pattern that encodes information as variations in the instantaneous phase of a carrier wave.

Phase modulation is widely used for transmitting radio waves and is an integral part of many digital transmission coding schemes that underlie a wide range of technologies like WiFi, GSM and satellite television.

Phase modulation is closely related to frequency modulation (FM); it is often used as an intermediate step to achieve FM. Mathematically both phase and frequency modulation can be considered a special case of quadrature amplitude modulation (QAM).


Figure: Phase Modulation 

Antenna Terminiology: Antenna Noise Temperature, Directivity, Antenna Gain

Antenna Noise Temperature: It is the measure of all the external noise collected by a receiving antenna. Measured in Kelvin (K). It varies with antenna diameter, elevation angle and antenna polarisation. The larger the antenna, the lower the noise temperature. Major noise sources are cosmic noise (caused due to sun, moon and starts) and ground noise; caused due to noise energy radiated from the soil. 

Antenna Directivity
Directivity is a fundamental antenna parameter. It is a measure of how 'directional' an antenna's radiation pattern is. An antenna that radiates equally in all directions would have effectively zero directionality, and the directivity of this type of antenna would be 1 (or 0 dB).

Silly side note: When directivity is specified for an antenna, what is meant is 'peak directivity'. Directivity is technically a function of angle, but the angular variation is described by its radiation pattern. 



Antenna Gain
The term Antenna Gain describes how much power is transmitted in the direction of peak radiation to the power that would be radiated in the same direction by an isotropic antenna. Antenna gain is more commonly quoted than directivity in an antenna's specification sheet because it takes into account the actual losses that occur.

A transmitting antenna with a gain of 3 dB means that the power received far from the antenna will be 3 dB higher (twice as much) than what would be received from a lossless isotropic antenna with the same input power. Note that a lossless antenna would be an antenna with an  antenna efficiency of 0 dB (or 100%). Similarly, a receive antenna with a gain of 3 dB in a particular direction would receive 3 dB more power than a lossless isotropic antenna. The gain figure is only applicable to a particular direction and frequency. 
 
Reference: www.antenna-theory.com 

Abbreviation Used in Satellite Communication

AFC --- Automatic Frequency Control
AFD --- Active Format Description
ALC --- Automatic Loudness/Level Control
AM ---- Amplitude Modulation
AOV --- Angle of View
APID --- Audio Payload Identifier 
APSK --- Amplitude and Phase-Shift Keying or Asymmetric Phase-Shift     keying 
ASI --- Asynchronous standard interface  or   Asynchronous serial interface


ATSC --- Advanced Television System Committee.
ATM --- Asynchronous Transfer Mode

AVC --- Advanced Video Coding
AVP ---  Advanced Video Processor 
BISS --- Basic Interoperable Scrambling System
BPSK --- Binary Phase Shift Keying 
BSS --- Broadcast Satellite Service
BW --- Bandwidth
C&D --- Contribution & Distribution 
CA --- Conditional Access
CAM --- Conditional Access Module 
CAS ---Conditional Access System
CAT --- Conditional Access Table 
CBER --- Convolutional Bit Error Rate / Channel Bit Error Rate
CBR --- Constant Bit Rate
CCW --- Counter Clock Wise
CDP --- Cisco Discovery Protocol
CNR --- Carrier to Noise Ratio
CPI --- Cross Polarization Isolation
CSM --- Control Status Message
DMS --- Digital Monitization System
DPCM --- Differential Pulse Code Modulation
DPSK --- Differential Phase Shift Keying
DQPSK --- Differential Quadrature Phase Shift Keying
DSB --- Direct Satellite Broadcast
DSM --- Device Status Message
DSNG --- Satellite News Gathering
DSS --- Digital Satellite System
DTH --- Direct To Home
DTTV --- Digital Terrestrial Television 
DVB --- Digital Video Broadcast
DVB-S --- Digital Video Broadcasting — Satellite
DVB-S2 --- Digital Video Broadcasting — Satellite — Second Generation 
ECC --- Error Correction Code.
ECMG --- Entitlement Control Message Generator 
EDH --- Error Detection and Handling
EDTV --- Enhanced/Extended Definition TV
EIRP --- Effective Isotropic Radiated Power OR  Equivalent Isotropic Radiated Power 
EIS --- Event Information Scheduler 
EMMG --- Entitlement Message Manager Generator 
ENG --- Electronic News Gathering
EPG --- Electronic Program Guide 
ETSI --- European Telecommunications Standards Institute
EVE --- Ericsson Virtualized Encoding 
FEC --- Forward Error Correction
FGM --- Fixed Gain Mode
FM --- Frequency Modulation
FSS --- Fixed Service Satellite
FTA --- Free to Air
GMT --- Greenwich Mean Time
GPS --- Global Positioning System
GUI  --- Graphical User Interface
HPBW --- High Power Beam Width
Hsync --- Horizontal Sync
IF --- Intermediate Frequency
IGMP --- Internet Group Management Protocol
LA --- Lighting Arrester
LHCP --- Left Hand Circular Polarization
LKM --- Link Margin
LM --- Link Margin 
LNA --- Low Noise Amplifier
LNB --- Low Noise Block downconverte
LNC --- Low Noise Converter
LO --- Local Oscillator
LTC --- Longitudinal Time Code
LV --- Laser Vision
MCPC --- Multiple Channel Per Carrier
MCTRF --– Motion Compensated Recursive Temporal Filtering
MER --- Modulation Error Rate
MGP --- Multicast Guard Protocol
MHEG --- Multimedia and Hypermedia Experts Group
MPE --- Multiprotocol Encapsulation
MPTS --- Multiple Program Transport Streams
MSM --- Multicast Status Message
MSps --- Mega Symbols per second
MSS --- Mobile Satellite Service
MVP --- Multiscreen Video Processing


NF --- Noise Figure  
OAC --- Over - air control 
OOK --- On Off Keying
PAA --- Phase Aligned Audio
PAT --- Program Association Table 
PCR --- Program Clock Reference
PCR PID ---  Program Clock Reference  Packet Identifier
PDG --- Private Data Generator 
PIN --- Personal Identification Number
PING --- Packet INternet Groper
PLL --- Phase Locked Loop
PLR --- Program Level Redundency 
PM --- Phase Modulation
PSI --- Program specefic Information 
PSIG --- Program Specefic Information Generator 
PSIP --- Program and System information Protocol 
PSK --- Phase Shift Keying
PVST --- Per-VLAN Spanning Tree
PWM --- Pulse Width Modulation
QAM --- Quadrature Amplitude Modulation
QPSK --- Quadrature Phase Shift Keying
RAI --- Random Access Indicator
RF --- Radio Frequency
RSS --- Receive Side Scaling
RX --- Receive
SBCA --- Satellite Broadcasting and Communications Association
SCPC --- Signal Channel Per Carrier
SCS --- SimulCrypt Synchronizer
SFN --- Single Freuency Network 
SHF --- Super High Frequency
SI --- Service Information
SMPTE --- Society of Motion Picture & Television Engineers
SNG --- Satellite News Gathering
SNMP --- Simple Network Management Protocol  
SNR --- Signal to Noise Ratio
SPG --- Sync Pulse Generator
SPTS --- Single Program Transport Streams
SSM --- Source Specefic Multicast 
SSPA --- Solid State Power Amplifier
SST --- Single Sideband Transmission
STB --- Set Top Box
STT --- System Time Table 
TC --- Time Code
TDM ---Tendburg Device Manager / Time Division Multiplexing
TDT --- Time and Date Table
TOT --- Time Offset Table
TWT --– Ttraveling Wave Tube 
TX --- Transmission
UHF --- Ultra High Frequency
UID --- Unique Identifier
UPS --- Uninterrupted Power Supply
UWB --- Ultra Wide Band
VAS---  Value Added Service
VCM  --- Video Coding Module
VE --- Virtual Ethernet 
VHF --- Very High Frequency
VION --- Virtual Input/Output Nodes 
VITC --- Vertical Interval Time Code
VPC --- Video Procesor Chassis
VPID --- Video Payload Identifier 
VSAT --- Very Small Aperture Terminal
VSWR --- Voltage Standing Wave Ratio
VTP --- VLAN Trabnking Protocol 
VTY --- Virtual Terminal Interface

Direct To Home (DTH) Service Provider In Africa, Pacific, North and Latin America

Entertainment is everywhere if we embrace things we see as entertaining. People around the world do enjoy their precious time and moment doing the thing they love. Some people entertain themselves going to club, dancing, partying, roaming, traveling, watching television shows, gossiping, reading books and what not. But major portion of entertainment for most of the people is watching television holding a remote controller to move from one channel to another. But entertaining with TV doesn’t come as it is unless you are connected to some kind of special satellite or cable service. And in America, this is easier to get cable service or direct-to-home service with number of choices to entertain. Direct-to-home, briefly DTH is basically a digital satellite television viewing services directly through satellite transmission. To dig little bit more, DTH service providers are ready to entertain you with variety of channels since, up above the earth, there are so many satellites stationed at six key positions in orbit. Now, you will be introduced with two different popular DTH service providers in America.

Th endless opportunities of TV entertainment are ready to serve you all over the America if you are connected to Direct TV. Direct TV is quite popular and American direct broadcast satellite service provider. This DTH service provider is a subsidiary of AT&T based in El Segundo, California. Launched on June 17, 1994, the satellite service of Direct TV aims to reach out with digital satellite television and audio services to households in the United States, Latin America and the Caribbean. Dish Network and cable television providers stand to be the primary competitors of Direct TV. Direct TV allows to watch DIRECT TV, movies, TV Shows, For Kids section, Networks, Playlist and more. Direct TV, being a DTH service provider in America, provides services include the equivalent of several local television stations, subscription television services, broadcast television networks, satellite radio services and private video services as well. Any subscribers hold utter liberty to get access to hundreds of channels through Direct TV. And this is the number 1 customer satisfaction of tv entertaining facility compared to ano other major cable networks or satellite providers. You can get the ultimate entertainment today with Direct TV having no start-up cost or equipment expenditure.

DishNetwork         

Dish Network is another direct-broadcast service provider in America established in 1996. It is a hugely popular broadcast satellite industry providing satellite television, audio programming, and interactive television services to both commercial and residential customers in entire US. And there had been a great record book for Dish network as providing services to 13.7 million televisions and 580,000 broadband subscribers. Established headquarter in Meridian, Colorado, Dish Network is rocking with 16,000 employees. The primary goal of Dish Network is to reach out to every households with fully entertained satellite television. The customers have their freedom to pick their choice of channels. This network holds number of innovations and the award-winning innovations including Hopper with Sling Whole-Home HD DVR and a Tailgater.     

Number of choices
However, these two giant DTH service providers are not only on the list of entertainment providers, as we have number of choices as well. To introduce,

North America                           
USA                                                                           
1. DirecTV                                                                    
2. Sky Angel                                                             
3. Dish Network
                                                                                      
Canada                                                                       
1.Bell TV                                                                   
2. Shaw Direct


Latin America 
Argentina 
1. DirecTV

Bolivia
1. Tuves HD

Brazil
1. Sky Brasil

Chile
1. DirecTV

Ecuador 
1. DirecTV

Uruguay
1. DirecTV

Venezuela
1. DirecTV

Mexico
1. Sky Mexico


Africa
 South Africa
1. DS TV 
2. Open View HD

Middle East 
1. BeIN
2. OSN


Pacific
Australia 
1. Austar
2. Foxtel
3. UBI World TV

New Zealand
1. Sky
2. Free View

Overall, DTH service providers in America are extensive to entertain all the households. We have number of choices to select which DTH service provider to pick, while we can choose Direct TV or Dish Network out of so many. Every single DTH Service providers more or less are offering similar kind of facilities but  service may alter according to the zone and country.      



What is Link Budget and Free space path loss ?

What is Link Budget?
A link budget is accounting of all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide, fiber, etc.) to the receiver in a telecommunication system. It accounts for the attenuation of the transmitted signal due to propagation, as well as the antenna gains, feed line and miscellaneous losses. Randomly varying channel gains such as fading are taken into account by adding some margin depending on the anticipated severity of its effects. The amount of margin required can be reduced by the use of mitigating techniques such as antenna diversity or frequency hopping.

A simple (General) link budget equation looks like this:
Received Power (dB) = Transmitted Power (dB) + Gains (dB) − Losses (dB)

The link budget is an important value that enables engineers to design systems based on the required sensitivity of a receiver at a particular distance.

The free space path loss is the loss in signal strength of a signal as it travels through free space. This value is usually calculated by discounting any obstacles or reflections that might occur. IEEE defines it as "The loss between two isotropic radiators in free space, expressed as a power ratio."
It is a value that is dependent on the distance, frequency and the gains in the system. The link budget calculation requires you to know the Free Space Path Loss.

Free Space Path Loss
The free space path loss is the loss in signal strength of a signal as it travels through free space. This value is usually calculated by discounting any obstacles or reflections that might occur in its path. IEEE defines it as "The loss between two isotropic radiators in free space, expressed as a power ratio." Enter the Frequency, Distance and System gains to calculate the Free Space Path Loss. It is expressed in dB.