Presented by:
Mohammed Nazeeruddin

---

[attachment=13036]
FACSIMILE TRANSMISSION
Introduction
Facsimile machines came into use in the early 20thcentury .
An international system of transmitting a written, printed, or pictorial document over the telephone system .
A form of telegraphy for the transmission of fixed, document with or without half-tones, with a view to their reproduction in a permanent form.
It scan’s it photo electrically and reproducing the image after transmission.
Wired transmission
Wireless transmission
Telephone transmission
Combination of telephone and photocopier.
The scanner records variation between light and dark areas of the document.
A photoelectric cell converts the dots into electronic impulses.
Receiving fax machine decodes the electrical impulses.
In facsimile systems using amplitude modulation, that form of transmission in which the maximum transmitted power corresponds to the maximum density of the subject.
In facsimile systems using frequencymodulationthat form of transmission in which the lowest transmitted frequency corresponds to the maximum density of the subject.
In an amplitude-modulatedfacsimile system, transmission in which the maximum transmitted power corresponds to the minimum density, i.e., the white area, of the object.
In a frequency-modulated facsimile system, transmission in which the lowest transmitted frequency corresponds to the minimum density i.e., the white area, of the object.
White facsimile transmission
Group 1 Facsimile
Group 2 Facsimile
Group 3 Facsimile
Group 3c Facsimile
Group 4 Facsimile
Data transferring speed 36.6kbps.
Average speed is around 14.4 kbps.
Laser
Inkjet
Thermal
Uses Internet.
Send or receive fax using email.
Needs fax number and account number.
Get faxes in email usually in pdf format.
Receives and send faxes from any location, where internet can be accessed.
Web faxing can also be much more secure than traditional faxing since faxes can be encrypted .
The entire faxing process is mobile; we can send and receive faxes any where any time
Faxing over internet protocol
There are national and international internet protocol faxing services that allow company and individual to send faxes over their internet protocol faxing networks for a fee.
Using fax over internet protocol, the digital data from the fax machine can be separated into packets for transmission.
The digital data requires less bandwidth than the analog data, so Foip is more efficient than analog faxing the transmission takes less time as a result.
Provides an immediate hard copy .
Documents cannot be altered.
Facsimile signals can be successfully transmitted and received over any normal voice circuit.
Requires only a fax machine and a phone line.
Fax transmission is secure in that it goes only to the phone number address .
Transmission of weather maps and military maps is especially important to military services.
Transmission of visual images by facsimile is a relatively slow process.
The speed of transmission is limited by the bandwidth capabilities of the interconnecting facilities.
A normal telephone circuit passes a voice band from approximately 300 to 3,500 Hz, or, in other words, a 3,200-Hz bandwidth.
This bandwidth limits facsimile transmission.
Insufficient bandwidth results in lack of contrast between light and dark shading.
Facsimile images are subject to distortion by circuit noise.
Speed control of transmitting and receiving facsimile reproducers is a critical item.
The principal cause of "ghosts" or shadows in a received facsimile picture is phase delay of signal Elements.