A communication device (e.g., a cable modem (CM)) includes a digital to analog converter (DAC) and a power amplifier (PA) that generate a signal to be transmitting via a communication interface to another communication device (e.g., cable modem termination system (CMTS)). The CM includes diagnostic analyzer that samples the signal based on a fullband sample capture corresponding to a full bandwidth and/or a subset (e.g., narrowband) sample capture to generate a fullband and/or subset signal capture (e.g., of an upstream (US) communication channel between the CM and the CMTS). The diagnostic analyzer can be configured to generate sample captures of the signal based on any desired parameter(s), condition(s), and/or trigger(s). The CM then transmits the signal to the CMTS and the fullband and/or subset signal capture to the CMTS and/or a proactive network maintenance (PNM) communication device to determine at least one characteristic associated with performance of the US communication channel.