A system, comprising: a magnetic field sense element configured to detect an external magnetic field; a magnetic field source proximate the magnetic field sense element and configured to provide a reference magnetic field that is detectable by the magnetic field sense element, wherein the magnetic field sense element is configured to produce a composite signal having a reference signal portion and a measurement signal portion, the reference signal portion being indicative of the reference magnetic field and the measurement signal portion being indicative of the external magnetic field; a power supply coupled with the magnetic field source and configured to provide a supply current through the magnetic field source for continuously generating the reference magnetic field while the system is in an operational mode. a processing circuit coupled with the magnetic field sense element, the processing circuit being configured to process the composite signal to produce a measurement output signal indicative of the external magnetic field; a qualification circuit coupled with the processing circuit at multiple test points (152, 184), the qualification circuit being configured to detect the reference signal portion at the multiple test points (152, 184) and determine an operability of at least a portion of the system from the reference signal portion detectable at each of the multiple test points (152, 184);. wherein: the processing circuit comprises an analog-to-digital converter, ADC, system configured to convert the composite signal to a digitized composite signal; and the multiple test points (152, 184) include a first test point, the first test point including a first interconnect between the ADC system and the qualification circuit, wherein the qualification circuit is configured to detect a digitized qualification reference signal portion of the reference signal portion in the digitized composite signal and produce a first error flag when the digitized qualification reference signal portion is outside of a first expected signal range. a magnetic field sense element configured to detect an external magnetic field; a magnetic field source proximate the magnetic field sense element and configured to provide a reference magnetic field that is detectable by the magnetic field sense element, wherein the magnetic field sense element is configured to produce a composite signal having a reference signal portion and a measurement signal portion, the reference signal portion being indicative of the reference magnetic field and the measurement signal portion being indicative of the external magnetic field; a power supply coupled with the magnetic field source and configured to provide a supply current through the magnetic field source for continuously generating the reference magnetic field while the system is in an operational mode. a processing circuit coupled with the magnetic field sense element, the processing circuit being configured to process the composite signal to produce a measurement output signal indicative of the external magnetic field; a qualification circuit coupled with the processing circuit at multiple test points (152, 184), the qualification circuit being configured to detect the reference signal portion at the multiple test points (152, 184) and determine an operability of at least a portion of the system from the reference signal portion detectable at each of the multiple test points (152, 184);. wherein: the processing circuit comprises an analog-to-digital converter, ADC, system configured to convert the composite signal to a digitized composite signal; and the multiple test points (152, 184) include a first test point, the first test point including a first interconnect between the ADC system and the qualification circuit, wherein the qualification circuit is configured to detect a digitized qualification reference signal portion of the reference signal portion in the digitized composite signal and produce a first error flag when the digitized qualification reference signal portion is outside of a first expected signal range. the processing circuit comprises an analog-to-digital converter, ADC, system configured to convert the composite signal to a digitized composite signal; and the multiple test points (152, 184) include a first test point, the first test point including a first interconnect between the ADC system and the qualification circuit, wherein the qualification circuit is configured to detect a digitized qualification reference signal portion of the reference signal portion in the digitized composite signal and produce a first error flag when the digitized qualification reference signal portion is outside of a first expected signal range.