Hardware Architecture
Chapter 1 Overview
TA 102/202 Technical Support Guide
1-7
Additionally, both line interfaces support all telephony services, such as Caller ID, Call
forwarding, Call Waiting, etc. For a European application, the POTS interface can func-
tion with equipment compliant to the European Telecommunications Standards Insti-
tute (ETSI) specification.
Speech Codec
How do you send analog voice signals to and from a telephone over a PacketCable
network? Actually you can’t, the analog voice signals must be converted to digital
signals and then sent over a PacketCable network. The device in an MTA responsible for
signal conversion is called a Codec. Figure 1-5 illustrates the function of a Codec.
Figure 1-5
A Codec at Work
In the TA 102/202 eMTA the Speech Codec (see Figure 1-3) is a Digital Signal Processor
(DSP). It carries out the analog to digital and digital to analog signal conversion. What’s
inside a DSP? A DSP contains these key components:
•
Program Memory: Stores the program the DSP uses to process data.
•
Data Memory: Stores the information to be processed.
•
Compute Engine: Performs the math processing, accessing the program from the
Memory and the data from the Data Memory.
•
Input/Output: Serves a range of functions to connect to the outside world.
PacketCable Network
"Hello"
"Hello"
MTA
MTA
Analog
Voice
Analog
Voice
Codec converts
analog to digital
Codec converts
digital to analog
