S/N of total intensity pulses versus integration time from the multifrequency simultaneous observations of PSR B0823+26. Upper to lower panels: Effelsberg 100-m at 2635 MHz using 80-s subintegrations; Lovell at 1532 MHz using 140-s subintegrations; WSRT at 345 MHz using 140-s subintegrations; LOFAR at 149 MHz using 110-s integrations. Discontinuation of lines indicates flagged subintegrations due to RFI. The periods of B-mode emission are indicated by the shaded grey backgrounds and labelled ‘B’.