Controllerless Modems
What are Controllerless Modems and Software Modems?
In general, Modem systems can be divided into three parts:
Controller: This part communicates with CPU via BUS interface, executes modem AT command sets, handles data access between application and Data Pump and executes the tasks of error correction and data compression algorithms.
Data Pump : This part handles float point operation like FFT, DTMF and other tones generation and detection, modulation and demodulation and sprectral analysis. This part is the engine of modem, the kernal of modem operation. It modulates data from controller and transmits the analog signals to DAA. It demodulates the received signals from DAA and send the data to controller.
DAA (Data Access Arrangement) : This part is analog circuits to provide the characteristics required to connect to the telephone network. The matching characteristics include line impedance, current sink and hybrid circuitry. DAA also enables features such as CallerID and pulse dialing.
A modem's type is determined by it's structure (how it implements these parts).
Hardware Modem: Contains Controller, Data Pump and DAA.
Controllerless Modem: As CPUs have become more and more powerful, internal modem structure can be saved by moving some parts to the CPU. By placing modem command execution on the CPU, manufacturers do not need to place the controller on the modem.
Software Modem: The tasks of controller and data pump are moved to the CPU, modem uses only ASIC to handle PC interface.
We do not recommend the use of Software Modems!
Make certain you are using the appropriate firmware revision with
the Controllerless Modem.
