<p>Aims. We analyse the Signal-to-Noise Ratio (SNR) requirements of the European Space Agency (ESA)-funded Solar Coronagraph for OPErations (SCOPE) instrument with respect to the manual and automatic detection of Coronal Mass Ejections (CMEs) in its field of view of 2.5 to 30 solar radii.<br />Methods. For our analysis, SNR values are estimated from observations made by the C3 coronagraph on the Solar and Heliospheric Observatory (SOHO) spacecraft for a number of di erent CMEs. Additionally, we generate a series of artificial coronagraph images, each consisting of a modelled coronal background and a CME, the latter simulated using the Graduated Cylindrical Shell (GCS) model together with the SCRaytrace code available in the Interactive Data Language (IDL) SolarSoft library. Images are created with CME SNR levels between 0.5 and 10 at the outer<br />field of view (FOV) edge, generated by adding Poisson noise, and velocities between 700 km s-1 and 2800 kms-1. The images are analysed for the detectability of the CME above the noise with the automatic CME detection tool CACTus.<br />Results. We find in the analysed C3 images that CMEs near the outer edge of the field of view are typically 2%of the total brightness and have an SNR between 1 and 4 at their leading edge. The automated detection of CMEs in our simulated images by CACTus succeeded well down to SNR = 1 and for CME velocities up to 1400 kms-1. At lower SNR and higher velocity of 2100 kms-1 the detection started to break down. For SCOPE, the results from the two approaches confirm that the initial design goal of SNR = 4 would, if achieved, deliver improved performance over established data used in operations today.</p>