The prediction technique developed by the National Bureau of Standards has been used extensively by high-frequency communicators. An adaption of this technique is used to demonstrate the type of results obtained when applied to the Buffalo, N.Y. to Boston, Mass. (B/B) link for January and July 1965. A new prediction technique is presented which will allow the HF communicator to predict system performance between the maximum useable frequency (MUF) and the lowest useable frequency (LUF) and which is flexible enough to allow system parameter changes to be made and the effect on the overall system determined. The new technique is demonstrated by applying it to the B/B link for January and July 1965 and displaying the results in the form of relative gain contours, which show the effect on communication capability of reducing the LUF by increasing system gain and the increase in process gain that may be achieved for the purpose of raising the data rate or decreasing transmission error rate. Some of the many applications of the results of this new technique are presented. The results are used: (1) to facilitate the selection of necessary operating frequencies to provide communication throughout a 24-hour period, (2) to estimate the severity and length of occurrence of multipath, (3) to investigate possible frequency adaption, and (4) to investigate possible power adaption.