Telecommunications

In telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

s, a back-to-back connection is a direct connection

Electrical connection

An electrical connection between discrete points allows the flow of electrons . A pair of connections is needed for a circuit.Between points with a low voltage difference, direct current can be controlled by a switch...

 between either:

1. the output of a transmitting device and the input of an associated receiving device. When used for equipment measurements or testing purposes, such a back-to-back connection eliminates the effects of the transmission
   Transmission (telecommunications)
   Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
   
    channel
   Channel (communications)
   In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...
   
    or medium
   Transmission medium
   A transmission medium is a material substance that can propagate energy waves...
   
   .
2. the output of a receiving device and the input to a transmitting device.

Source: from Federal Standard 1037C

Federal Standard 1037C

Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended....

 and from MIL-STD-188

MIL-STD-188

MIL-STD-188 is a series of U.S. military standards relating to telecommunications.-Purpose:Faced with “past technical deficiencies in telecommunications systems and equipment and software…that were traced to basic inadequacies in the application of telecommunication standards and to the lack of a...

Electronics

A back to back connection is 2 identical or similar components connected in series with the opposite polarity. This is used to convert polarised components to non-polar use. Common examples include:

• electrolytic capacitor
  Electrolytic capacitor
  An electrolytic capacitor is a type of capacitor that uses an electrolyte, an ionic conducting liquid, as one of its plates, to achieve a larger capacitance per unit volume than other types. They are often referred to in electronics usage simply as "electrolytics"...
  
  s
• zener diode
  Zener diode
  A Zener diode is a special kind of diode which allows current to flow in the forward direction in the same manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "Zener knee voltage" or "Zener...
  
  s

Power transmission

A back to back connection in energy transmission is found where an HVDC system is used where both stations are on the same switchyard. Such device is used for coupling asynchronously operated power grids or for connecting power grids of different frequency and/or phase count where no DC transmission is necessary.