- T.30 Fax Protocol
- T.30-E Color Fax Protocol
- T.30 Error Correction Mode
- Image Format Conversion
- T.6, MMR Image Format Conversion
- JBIG Image Format Conversion
- T.4 Copy Quality Checking/Correction
VOCAL’s fax protocol software is optimized for DSPs and conventional processors from TI, ADI, Intel, ARM and other leading vendors. Our fax protocol software may be licensed standalone, as part of a library or with a VoIP stack for integration with a developer’s application. Custom designs are also available to meet your unique fax requirements. Contact us to discuss your Group 3 fax/facsimile application requirements.
Group 3 Fax/Facsimile
Group 3 fax devices conform to the ITU-T T.4 and T.30 Recommendations which manage the procedures used for image conversion and fax transmission. This includes the T.4, T.6, and T.30 protocol stacks. Included as well is the T.30E module, which is necessary for the transmission and reception of colour fax. Group 3 fax “high speed” modulations include V.17 (14.4 kbps, 12.0 kbps, 9.6 kbps, and 7.2 kbps), V.29 (9.6 kbps and 7.2 kbps), and V.27ter (4.8 kbps and 2.4 kbps). V.33 is no longer specified as an option under T.30.
T.30 specifies an additional 14 modulation rates between 2400 bps and 33600 bps (in increments of 2400 bps) that can be used from the V.34 modulation. This is referred to as V.34 Fax. As with V.34 data modulation procedures, V.8 startup is required. V.34 Fax includes procedures for full and half duplex data channel operation; half duplex is mandatory for V.34 Fax support.
In non-V.34 Fax, V.21 is used to transport T.30 control information frames. V.34 half-duplex procedures define a 1200 bps and 2400 bps control channel. In V.34fax, this control channel is used to transport T.30 control information frames. The use of error correction mode for V.34 Fax is mandatory.
The binary coded signalling system is based on a High Level Data Link Control (HDLC) format developed for data transmission procedures. This provides for frame labelling, error checking, and confirmation of correctly received information. Error correction mode is optional for some fax image formats (T.4) and mandatory for other compressions (T.6).
Other features of Group 3 Fax include image compression algorithms such as T.4 1-D and 2-D coding, T.6 compression, JPEG gray scale and color modes. Image format conversion, although not specified by T.30, is an optional feature of facsimile service class 2 command sets. Binary file transfer (BFT), is a mechanism to transport aT.454 format file under error correction.
- Fully compliant with ITU Recommendations
- Supports control of facsimile high speed modulations up to V.34fax 33,600 bps.
- T.30 session control and negotiation
- Supports fax polling operation
- Supports procedure interrupts
- Optional Error Correction Mode (ECM) available
- Optional Binary File Transfer (BFT) available
- T.4 1-dimensional Fax Image Decoding/Reencoding
- T.4 2-dimensional/ T.6 Fax Image Decoding/Reencoding available
- In-band data format conversion support available
- Multi-tasking environment compatible
- Multichannel implementation
- DAA interface using linear codec at 7.2 kHz, 8.0 kHz or 16.0 kHz sample rate
- Direct interface to 8.0 kHz PCM data stream (A-law or μ-law)
- North American and International Dialing/Telephony dialing functions available
- Facsimile protocol layer (T.30 with ECM/BFT) available
- Facsimile service class 1 command sets (T.31 and EIA-578) available
- Facsimile service class 2 command sets (T.32, EIA-592 and industry standard fax class 2) available.
- System can be combined with V.34fax facsimile modulations and startup procedures (V.8 and V.8bis).
- Configurable for standalone operation (no command set layer required).
- T.38 Fax Relay/Fax over IP configurations available
- Error Correction Mode memory can be maintained off-system.