3Jtech uModem Technical Document page 3

FUNCTION DESCRIPTIONS
ZyDAS USB modem uses a hardware-based
DSP core to handle both the modem signal
processing and modem protocol processing in a
single chip. and an embedded USB logic to
process host USB traffic in a single chip. This
chip supports to run
implementation and voice compression algorithm
processing for Telephone Answering Machine
(TAM) application. The major functions of ZyDAS
USB modem are described below.
USB functions
● CDC 1.1 compliant for different platforms:
CDC, communication device class for USB
devices, is an interface between USB hosts and
USB devices. The purpose of CDC is to support
all kinds of communication services on the USB.
ZyDAS USB USB modem meets the CDC version
1.1 specifications and can talk to hosts supporting
CDC driver. No special USB drivers are needed
in such kind of hosts. Currently, the Win 98 SE,
Win 98 ME, Win 2000 and MacOS.9.0 are all
CDC ready. ZyDAS also provides the USB CDC
drivers for the first edition of Win98 system.
● Power management - suspend and resume:
USB hosts can supply power to USB devices
directly connected to the bus. USB hosts may
also have the power management capability to
suspend or resume the USB bus-powered
devices in any power-sensitive
applications such as NB or PDA. ZyDAS 56K
USB modem solution
management chip - ZD1056, which can allow the
USB host to order the modem to enter into
suspend mode to save power consumption.
ZyDAS 56K USB modem will resume from
suspend state when ordered by the host. In
addition to this, the modem can also resume and
trigger a remote-wake-up signal to the host when
there is an incoming call.
Data/Fax mode
Data and fax mode auto discrimination:
●
Data or fax incoming calls can be automatically
recognized as a data or fax connection without
the user intervention.
Multi-auto mode V.90 modem:
●
In ITU-T V.90 data mode, ZyDAS USB modem
can receive data at speeds up to 56K bps while
connecting to a digitally connected central
modem. Due to the PSTN network's digitization,
only the client modem to central office local loop
is not digital. This V.90 data pump is very suitable
for remote access applications such as Internet
access, remote on-line service and corporate
data base access.
2003/6 From 3JTech
a data/fax modem
portable
includes a power
Revision 1.0
Research & Development
ZyDAS 56K USB modem conforms to ITU-T V.34
standard, operates in two-wire full duplex
asynchronous mode at line speeds up to
33.6Kbps. Based on ZyDAS's own DSP algorithm,
this modem can maintain high quality connections
at high speeds especially under adverse line
conditions. It will automatically fall back to lower
speeds when communicating
modems or when line condition degrades.
ITU-T T.30 fax protocol describes the G3 fax
handshake signals and procedures. ZyDAS USB
modem takes full control of this protocol, initiates
and terminates fax
communication session and transports the image
data, provides the highest fax speed of up to 14.4
Kbps using the fax transmission standard V.17.
This modem supports TIA Class 1, Class 2 and
Class 2.0 command sets.
Voice mode
Voice mode of ZyDAS USB modem stands for the
ability to digitize incoming voice messages such
that the computer can store and forward them. It
also playbacks the recorded digitized voice on
line for a message announcement. This modem
uses 9.6 KHz/ 8KHz sampling rates and chooses
a high voice quality 4-bit ADPCM algorithm to
reduce the speech data rate. IS-101 voice
command set and
supported.
World wide homologation
ZyDAS USB modem uses the programmable
silicon DAA Si3034/ Si3035 as the analog front
end. The Si3034 DAA which is the international
version meets most of the world wide PTT
specifications and Si3035, the FCC version,
meets the FCC PTT specification. ZyDAS
provides a tool to change the parameters used for
call progress monitoring, dialing, and ring
detection. Modem designer can use this tool to
change the PTT parameters to precede the new
PTT type approvals. The parameters for CTR21
and FCC Part 68 compliance are provided.
Reference design
A reference USB bus modem design with
data/fax/TAM function is ready for evaluation.
This design can pass the pretest of EMC, safety
and PTT certifications. The schematic, BOM,
board layout of this design are all available.
Designer can use this as a reference to shorten
the design cycle and finish the prototype rapidly.
with slower
calls, manages the
DTMF detection are
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