Hourly distributions of the angle ϑxB=arccos (X⋅B), where X is the solar ecliptic earth-sun axis and B is the interplanetary magnetic field (IMF), have been compared with hourly Pc 3 and Pc 4 signal activity at Calgary for 198 hours in September, October, and November 1969. Hours whose distributions were concentrated above or below ϑXB=50¿ were correlated with a clear separation of inactive from active micropulsation intervals. The correlation was stronger for the Pc 3 than for the Pc 4 band, and hours with significant fractions, say 10--20% of their ϑXB distributions below 30¿, corresponded particularly well with high amplitudes of micropulsation signals. Signals in the Pc 3 period range on the ground can therefore be used as a crude monitor of certain extremes of IMF orientation.