Lapisan fisik

**Lapisan fisik** ( ) nyaéta hiji hambalan kahiji tina tujuh hambalan model OSI dina jaringan komputer, ogé mangrupa hambalan kahiji tina lima hambalan dina model rujukan TCP/IP. Lapisan ieu ngawangun layanan nu dipaké dina lapisan tumbu data (*data link layer*). 

The physical layer is the most basic network layer, providing only the méans of transmitting raw bits rather than packets over a physical data link connecting network nodes. No packet héaders nor trailers are consequently added to the data by the physical layer. The bit stream may be grouped into code words or symbols, and converted to a physical signal, which is transmitted over a physical transmission medium. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes of the electrical connectors, which frequencies to broadcast on, what modulation scheme to use and similar low-level paraméters are specified here. An analogy of this layer in a physical mail network would be the roads along which the vans carrying the mail drive.

## Physical signaling sublayer 
In a local area network (LAN) or a metropolitan area network (MAN) using open systems interconnection (OSI) architecture, the *physical signaling sublayer* is the portion of the physical layer that:
* interfaces with the medium access control sublayer (MAC) which is a part of the Data Link Layer
* performs character encoding, transmission, reception and decoding
* performs mandatory isolation functions.

Source: from Federal Standard 1037C

## List of Physical layer services 
The major functions and services performed by the physical layer are: 
* Bit-by-bit node-to-node delivery
* Providing a standardized interface to physical transmission media, including 
** Mechanical specification of electrical connectors and cables, for example maximum cable length
** Electrical specification of transmission line signal level and impedance 
** Radio interface, including electromagnetic spectrum frequency allocation and specification of signal strength, analog bandwidth, etc.
** Specifications for IR over optical fiber or a wireless IR communication link
* Modulation
* Line coding
* Bit synchronization in synchronous serial communication
* Start-stop signalling and flow control in asynchronous serial communication 
* Circuit mode multiplexing, as opposed to statistical multiplexing performed at the higher level
** Establishment and termination of circuit switched connections
* Carrier sense and collision detection utilized by some level 2 multiple access protocols
* Equalization filtering, training sequences, pulse shaping and other signal processing of physical signals
* Forward error correction, for example bitwise convolutional coding
* Bit-interleaving and other channel coding

The physical layer is also concerned with
* Point-to-point, multipoint or point-to-multipoint line configuration
* Physical network topology, for example bus, ring, mesh or star network
* Serial or parallel communication
* Simplex, half duplex or full duplex transmission mode
* Autonegotiation

## Conto lapisan fisik 
* Modem jaringan telepon V.92
* Lapisan fisik IRDA
* Lapisan fisik USB
* Firewire
* EIA RS-232, EIA-422, EIA-423, RS-449, RS-485
* ITU Recommendations: see ITU-T
* DSL
* ISDN
* T1 and other T-carrier links, and E1 and other E-carrier links
* 10BASE-T, 10BASE2, 10BASE5, 100BASE-TX, 100BASE-FX, 100BASE-T, 1000BASE-T, 1000BASE-SX and other varieties of the Ethernet physical layer
* Varieties of 802.11
* SONET/SDH
* Antarbeunget GSM
* Lapisan fisik Bluetooth
* Lapisan fisik Wi-Fi IEEE 802.11x
* Etherloop
* Hybrid Fibre Coaxial

## Conto kalengkepan hadwér (titik jaringan) 
* Adapter jaringan
* Repeater
* Hub jaringan
* Modem

*Note: Physical layer*
Associated with transmission of unstructured bit stréams over a physical link.
Responsible for the mechanical, electrical and procedural characteristics that
establish, maintain and déactivate the physical link.

## Tempo ogé 
* Ethernet physical layer
* Line code

## Rujukan 
* http://www.erg.abdn.ac.uk/users/gorry/course/phy-pages/phy.html
* http://www.tcpipguide.com/free/t_PhysicalLayerLayer1.htm