Abstract: A system and method for allowing multiple digital subscriber line modems to access a telephone line. The embodiments employ additional signaling protocols to enable equipped modems to distinguish between initiating and responding signals from initiating customer premise modems and telephone company central office devices. The additional signaling can take many forms that can be detected and used to distinguished signals. Preferably, the signal is a stealth signal as to not interfere with existing communication devices. A variety of application and embodiments are disclosed to enable a solution allowing multiple modems to access a telephone line.

Abstract: Analog to digital converter of the type in which an analog input signal is integrated and charge is applied to the integrating capacitor in predetermined measured quantities to offset or balance the effect of the input signal. A counter is incremented and decremented in accordance with the balancing charge to provide a count corresponding to the input signal. Means is included for eliminating errors due to offset voltages and imperfections in the virtual ground of the integrator, and the operating level of the integrator during a conversion is set independently of the sources which supply the balancing charge.