Abstract: Methods and circuits for synthesizing two or more signals phase-locked to a common reference frequency signal are disclosed. In one embodiment, a method comprises generating first and second output signals phase-locked to a reference clock signal, using first and second phase-locked loop circuits. In response to a detected frequency error in the first output signal, the first output signal is corrected by adjusting a frequency-division ratio in the first phase-locked loop circuit. The second output signal is corrected, separately from the correction to the first output signal, by adjusting a frequency-division ratio in the second phase-locked loop circuit, using an adjustment parameter calculated from the detected frequency error. In another exemplary method, first and second output signals are generated as described above, using first and second phase-locked loop circuits.

Abstract: Methods and circuits for synthesizing two or more signals phase-locked to a common reference frequency signal are disclosed. In one embodiment, a method comprises generating first and second output signals phase-locked to a reference clock signal, using first and second phase-locked loop circuits. In response to a detected frequency error in the first output signal, the first output signal is corrected by adjusting a frequency-division ratio in the first phase-locked loop circuit. The second output signal is corrected, separately from the correction to the first output signal, by adjusting a frequency-division ratio in the second phase-locked loop circuit, using an adjustment parameter calculated from the detected frequency error. In another exemplary method, first and second output signals are generated as described above, using first and second phase-locked loop circuits.

Abstract: Lockup in escaped mode for asynchronous paired modems on a communications link utilizing DTE echo back verification protocol is prevented by adding logic to each modem to detect and suppress transmission by the modem to its paired modem of at least one of any escape sequence characters received by a modem from its attached DTE. This prevents the unintentional placement of the paired modem, which would otherwise be transmitting echoed back characters from its DTE, from entering into the escape mode of operation due to what it would recognize as "escape sequence" characters received as "echo back" verification from its DTE.

Abstract: The invention permits multiple secondary stations to be connected in a multipoint communication network to a single primary station utilizing point-to-point interfaces such as the standard RS-232 or V.35 which do not ordinarily support multipoint connections. A primary station is connected to one secondary station or modem through a point-to-point interface utilizing either a straight through or cross over cable depending upon whether a modem is included. Data goes through the secondary station or modem to a second interface which is connected to a different secondary station or modem. This type of connection is referred to as a daisy chain. Data is not buffered in the secondary stations but is transmitted directly through each station. Each station monitors the daisy chain signals for clocking, status and identification of data for itself. Since there is no buffering, only a single set of clocking can be used in the chain.