Complete Communications Engineering

Fax Modem Data Modulations & ProtocolsVOCAL’s Fax modem solutions provide a range of fax modulations and protocols for a variety of facsimile applications and fax communications over Internet, radio, mobile, PSTN and other IP networks. Our Super/Group 3 fax softmodem designs include high speed V.34 and V.17 fax as well as T.30 protocol and T.38 fax solutions. Contact us to discuss your fax modem application requirements.

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VOCAL’s fax modem software libraries include support for Super/Group 3 Fax as well as a complete range of ETSI / ITU / IEEE compliant algorithms. Our source code is optimized for performance on ANSI C and leading DSP architectures from TI, ADI, Intel, ARM and other vendors. VOCAL’s fax software may be licensed as a library or part of a complete design with custom solutions available.


Fax Soft Modem

All of VOCAL’s facsimile modulations and data streams can be controlled with our T.30 protocol functions or with VOCAL’s facsimile service class 1 command sets (EIA-578 and T.31). The T.30 functions could in turn be controlled with VOCAL’s facsimile service class 2 command sets such as T.32 (known as fax class 2.1), EIA-592 (known as fax class 2.0) and industry standard (known as fax class 2). Typical systems can be configured to use T.30 Error Correction Mode (ECM), T.4 copy quality checking/corrections and perform image form conversion for T.4/T.6 and JBIG.

The line interface may be an analog front end (codec and DAA) or a digital interface such as T1/E1, xDSL, ATM, and ISDN. The application interface of this software can support a fax class 2/2.0/2.1 command set or may be used directly by an application.

The fax modem software uses signal detectors to determine the progress of a call by audio means, obtaining user pressed DTMF digits and mode transitioning. The signal detectors and generators include: