The data fax modem is a very functional machine that has the benefits of security and reliability. It utilizes the antiquated technology of telephone lines while still making use of modern digital enhancements. The system is very simple and results in almost instantaneous transmission of information.
Instructions
Transmission and Reception
1. The sending data fax modem dials a phone number and sends a white noise audio signal via the telephone line or internet to the receiving data fax modem and waits for confirmation of reception.
2. The two modems go through the “handshake” process in which they let each other know the type of data fax they are, whether analog or digital, and confirm that the telephone line is clear and can make a proper transmission. The most common types of fax are Group 3 and Super Group 3 digital data fax modems.
3. The two modems decide what type of data compression to use and what speed to send the information. Compression techniques are dependent on each classification of the data fax modem. Modified Huffman is based on compressing the white space of the data in the signal while Modified Read compares the first line to the second, changing the signal due to the changes in lines. Super Group 3 usually sends at a minimum of 14.4 kbit/s but can go as fast as 33.6 kbit/s.
4. The scanned image or attached data if sending Fax Over IP gets digitally compressed and sent as a series of analog signals to be digitally uncompressed by the receiving data fax modem. The different types of scanning depend on the individual machine and can either be done horizontally or vertically, ranging from basic 100 line scans to the “Veryfine” scan of 400 lines.
5. The receiving unit begins getting data or informs the sending unit that it is having interference. The sending unit then steps down to a lower speed of transmission. If the signal is still having difficulty the sending unit disconnects and the transaction is canceled. This usually occurs if there is noise in the telephone line from a break or storms.
6. The receiving data fax modem obtains information for each page, getting a specialized audio signal when there is a page break and ultimately receives a final analog signal from the sending machine notifying it that there is no more information to be sent.
7. The receiving unit confirms that it has received the information and the sending unit disconnects.
8. The receiving data fax modem orders a printer to print the data or stores it as a file on a computer, usually as a .TIFF or .PDF. There is no record of the transaction other than on the two machines, adhering to various HIPAA and Sarbanes-Oxley Laws about confidentiality. Each machine is capable of confirming transmission and reception and a record of the entire process is stored in the data fax units' memory for troubleshooting needs.
