Some systems require an application where a “sniffing” feature (a standby card also serves as a line condition monitor) is preferred from a redundant system. As shown in the figure below, an application proposal is made to achieve just that by using analog switches and attenuation resistors. Analog switches are configured as such that the primary card is operational in normal mode while standby card, while serving as a redundant card upon the failure of primary card, is monitoring the line condition through a 432Ω resistor simulating a high-impedance bridging circuit commonly used in a digital cross-connect settings. The 432Ω resistor is used to avoid interfering signals in primary card. SuperJet has built in a Monitor Gain circuit which is able to amplify the attenuated signal by 22dB/26dB/32dB configurable by software. Refer to application note AN-858 for more details. For other questions not addressed by the Knowledge Base, please submit a technical support request.