From: wolfgang@netcom.com (Wolfgang Henke)
Subject: Re: DSP code for modem functions?
Organization: Netcom
X-Newsreader: Tin 1.1 PL5
Date: Tue, 15 Dec 1992 17:44:48 GMT

"Michael Smith" (p00004@psilink.com) wrote:
: modulation technique were in "soft" (i.e. downloadable) code, as 
: insurance against firmware bugs and for purposes of upgrading as new 
: techniques are defined.

Soft.. Here is an info file on softmodem technology from Digicom. 

		SOFT MODEM BY DIGICOM SYSTEMS, INC.

MDK-200 Modem Design Kit
Software Installable V.32bis/V.42bis/Group 3 FAX Algorithms

The Digicom Systems MDK-200 is a V.32bis/V.42bis and Group 3 FAX modem 
design kit based on a new generation of software installable and
upgradeable high-speed communications technology. The SoftModem or
"modem on a disk" runs on an Analog Devices 2100 series digital signal
processor (DSP) and includes the DSP algorithms for CCITT data and FAX
modulation standards. The data compression and AT command controller
functions are also supported as integrated DSP algorithms making this
single processor solution the industry's lowest-cost V.32bis and FAX
modem design.

The SoftModem algorithms are stored in the host computer's memory and
require the assistance of a totally RAM-based DSP hardware subsystem.
The CCITT compatible data and FAX algorithms are downloaded via the PC
bus into the external RAM on the DSP platform for traditional
communications. The Digicom Systems SoftModem is compatible with the
CCITT V.32bis, V.32, V.22bis, V.22, V.23 and Bell 212A data modulation
standards to support data rates of 14400, 12000, 9600, 7200, 4800, 2400
and 1200 bps. CCITT V.42bis and MNP(tm) 5 data compression deliver
effective throughput up to 57,600 bps while CCITT V.42 and MNP classes
2, 3 and 4 ensure error-free data transmission.

The Group 3 FAX V.17, V.29, V.27ter and V.21 standards are also
supported providing FAX transmission at speeds of 14400, 12000, 9600,
7200, 4800 and 2400 bps. Industry standard AT commands and EIA/TIA-578
Class 1 FAX commands ensure compatibility with all of the popular data
and FAX communications software packages.

Storing the SoftModem's DSP algorithms in the host computer's memory
eliminates the need for ROM or EPROM memory on the DSP hardware platform
thus reducing the technical support and feature upgrade process to a
simple file transfer.

Features				Benefits
----------------------------------------------------------------------

Software upgradeable DSP algorithms     Timely technical support and
via simple file transfer                availability of new features
					enhancements

Requires a single low-cost DSP with     Reduces cost, power and hardware
integrated controller functions         requirements

CCITT V.32bis/V.32/V.22bis/V.22/V.23    Ensures compatibility with old
and Bell 212A data modulations          and new data communication 
					standards

V.17/V.29/V.27ter/V.21 FAX modulations  Worldwide FAX compatibility

V.42bis and MNP 5 data compression      Provides error-free data
and V.42 error control (LAPM and MNP)   transfer and increases throughput
					by up to 4:1

Extended AT data commands and EIA-578   Compatible with applications
Class 1 FAX command interface		software

ADPCM voice upgrade capability          Future availability of voice 
					technology

Supports Signal Computing Architecture  Extendable to multimedia
					applications


Functional Description
------------------------------------------------------------------------

I--------I         I------------I      I-------I      I-------I
I        I         I            I      I       I      I       I
I SRAM   I---------I ADSP210X   I------I 28msp1I -----I  DAA  I    
I        I    I    I   (DSP)    I      I (AFE) I      I       I
I--------I    I    I------------I      I-------I      I-------I
	      I          I                                I
	      I          I                                I
	      I      I--------I                           I
	      I      I        I                           I
	      I------IINTFC200I				LINE
		     I        I
		     I--------I
			 I
			 I
		      PC BUS

Integrated DSP Controller
The MDK-200 SoftModem design kit requires only a single ADSP-2100 series
DSP from Analog Devices to support all of the data, FAX and voice
transmission algorithms as well as the V.42bis compression and AT
command control functions. The 2100 series of 16-bit fixed-point DSPs
are optimized for high-speed numeric processing and offer a direct
upgrade path to code compatible higher-performance signal processors
from Analog Devices.

High-Performance Analog Front-End
The AD28msp01 is a PSTN signal port analog front-end for
high-performance modems. The chip uses advanced sigma-delta technology
for echo-cancelling applications to achieve robust bit error rates under
worst line conditions.

RAM-Based Memory 
The MDK-200 specifies that 32K x 24 bits of static RAM be used as shared
program and data memory. This memory stores the DSP algorithms
downloaded from the host computer for execution by the DSP and is
additionally used for bulk delay and V.42bis data memory.

Interface Circuit
The INTFC200 bus interface chip supports the ISA parallel bus interface,
DMA emulation for algorithm booting, 16550 UART emulation, high-speed
serial port interface to the DSP and I/O control functions.

Signal Computing Architecture
The SoftModem technology and MDK-200 design kit are compatible with the
Signal Computing open systems architecture from Analog Devices allowing
integration of other multimedia algorithms such as speech recognition
and audio and video compression.




This kit is expected to be available in October/November 1992 for modem
manufacturers or developers.


-- 
   _________________________________________________________________________
   Wolfgang Henke     Data lanes not car pool lanes      wolfgang@netcom.com 

Newsgroups: comp.dsp