Fax Demodulator and Decoder (FaxDD, FaxDDT.38)

Fax Demodulator and Decoder
(FaxDD™, FaxDDT38™)

Overview

FaxDD™ application is used for processing captured files and produce the Fax TIF image and other transmission information. The application is available as FaxDD™ (VBA038) and FaxDDT38™ (PKV104). The VBA038 has two versions – one, as a stand-alone command-line fax analysis application and other, integrated as a module within GL's Voice Band Analyzer application. FaxDDT38™ or the PKV104 is a stand-alone command-line fax analysis application for packet captures.

		User Manual
		Product Brochure

FaxDD™ is a fax decoder/demodulator application that processes 2-Wire or 4-Wire captures and analyzes voiceband traffic files for fax traffic. Call-center quality systems, brokerages, government agencies, and other entities have a need to monitor fax transactions between two parties. In some cases, the monitoring is done by recording the PCM stream for later conversion to a viewable format. The output of this application includes fields for fax success/failure, data rate, resolution, compression (Modified-Huffman, Modified-Read, Modified-Modified-Read), page size, error-red lines, total lines, total bytes, total pages, image name, and log file name.

GL’s FaxDDT38™ software converts PCAP files and outputs of packet capture applications such as PacketScan™ or Wireshark, into TIFF-F files containing the fax image. FaxDDT38™ also provides analysis of the T.38 packets, T.30 frames, and general call-flow indicators. So it is a valuable T.38 debug and test tool, aiding significantly in system development.

Main Features

2-wire or 4-wire captures, A-Law, µ-Law, 13-bit linear PCM, and16-bit linear PCM data formats.
Operates stand-alone from a Batch file or Windows Command screen or as part of the GL VoiceBand Analysis application to produce decoded fax image TIFF files and call logs
Output contains page-by-page packet statistics and Fax image summary.
Fax image output in TIFF-F format.
Reports Transmission Result
- NO_FAX: Input is not a fax signal (no V.21 flags detected).
- FAX_NO_PAGES: Input is a fax signal but no pages were recovered.
- COMPLETE_SUCCESS: All pages recovered had less than 10% bad lines.
- PARTIAL_SUCCESS: At least one page had more than 10% bad lines.
- NSS_MODE_ON: Session is using non-standard facilities as opposed to T.30.
Reports Modem Rate, Resolution, Encoding, and Page Size
- 2400, 4800, 7200, 9600, 12000, or 14400 bits per second.
- HIGH (204x196dpi), LOW (204x98dpi), or SUPER_HIGH (204x391dpi).
- Modified Huffman (MH), Modified READ (MR), or Modified-Modified READ (MMR).
- A4, B4, or A3.
Supports analysis of files captured by popular IP capturing tools. T.38 version 1 is supported.
Single- and multi-page ECM and non-ECM fax sessions are supported.
Decoding of transmitter-only captures is supported for non-ECM faxes.

Fax messaging

Typical Fax call - 2 page Fax shows a typical message exchange for a standard fax without error correction.

Screenshot of two page fax call

Run FaxDD™ From Batch File

Files can be processed on a per line basis in a DOS CMD window or more conveniently by using Batch files.

Batch File Operation

Files can be processed on a per line basis in a DOS window or more conveniently by using Batch files. Generally, running FaxDD™ through a batch script avoids the tedious process of bringing up the Command Window manually, and keying in a command for each analysis to be conducted.

Screenshot of Batch File Operation

Command Line Syntax

The FaxDD™ command line syntax is:

FaxDD38 -f capture-file-name [-d output-folder] [-o output-file-name] [-v]

Where

-f capture-file-name = input capture file
-d output-folder = folder to output TIFF-F files.
-o output-file-name = output TIFF-F files name.

For example, if two T.38 calls are present within the capture file and output-file-name is “fax_capt”, the first image will be saved with the name “fax_capt_1.tif” while the second will be named “fax_capt_2.tif”.

Integrated into Voice Band Analyzer (VBA)

The Fax Decode / Demodulator is integrated as an optional module in the GL Voice Band Analyzer. It can be used to analyze both 2-wire and 4-wire voice band captures for all types of traffic including Fax traffic. The Voice Band Analyzer can be set up for Manual, Batch, and Automatic operation.

Screenshot of VBA and Auto Setup

Select Display and Reporting

Users can decide if they want fax images only or to include the log file with additional information on messages used during the fax transaction. Also selectable are the fields displayed in the main application screen

Screenshot of Display and Parameters

Fax Image—TIFF Decode

FaxDD™ generates output in TIFF – F (Tagged Image File Format) files, the common file format for the exchange of image files where Class F TIFF files are specific for the exchange of fax images.

Screenshot of Tiff Image and Log File

Fax Log File

The FaxDD™ also generates a log file along with the TIFF file. Some of the parameters are:

Bad Lines - The number of bad lines received.
Total Lines - The total number of lines.
Pages - The number of pages processed.
Bytes - The number of bytes processed by the high-speed (non-V.21) modem.
Trains - The number of training signals processed.
Sender ID - The sending fax machine identification number.
Receiver ID - The receiving fax machine identification number

FaxDDT38™ — Decode T.38 CAP files

FaxDDT38™ is GL's command-line fax analysis application for packet captures. The Fax-over-IP packet protocol is defined in ITU-T Recommendation T.38, thus the “T38” in the product name. The following features are supported:

Analysis of files captured by popular IP capture tools. T.38 version 1 is supported.
Single- and multi-page ECM and non-ECM fax sessions are supported.
Decoding of transmitter-only captures is supported for non-ECM faxes.
ECM faxes must have both transmitter and receiver packets present in the capture.
Output contains page-by-page packet statistics and Fax image summary.
Fax image output in TIFF-F format.

FaxDDT38™ — Log File

FaxDDT38™ generates a log file with a summary of the fax call parameters as shown the figure below.

Screenshot of T38 Log File

Verbose Output

Verbose output is useful in examining the T.38 protocol. When verbose output is enabled, each packet is decoded and its type is printed. T.30 events are also decoded and shown. A small section of verbose output is shown in the figure below. You should use caution when requesting verbose output, as log files are much larger than those generated without verbose output.

Screenshot of Verbose Output

Buyer's Guide:

	Related Software
Item No.	Item Description
VBA038	FaxDD™
PKV104	FaxDDT38™
VQT022 VQT022a	VQuad™ Fax Emulation (2 simultaneous ports) VQuad™ Fax Emulation (8 simultaneous ports)
DM060 DM480	Fax License (60 global faxes) Fax License (up to 480 global faxes)
VBA032	Near Real-time Voice-band Analyzer
PKV100	PacketScan™ (Online and Offline)
VQT035	2-Wire Voice/Data Capture
FXT001	GL Insight Single Fax Analysis - TDM
	Related Hardware
UTE001	Portable USB based Dual T1 or E1 Laptop Analyzer with Basic Analyzer Software
VQT241	Dual Universal Telephony Adapter (UTA)

Specifications are subject to change without notice.

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