Click the PTP menu item under "Study Type" on the main screen. Set the starting point and the end point azimuths using the "Study type" sliders.
PTP studies use the exact algorithm used by the FCC it is proposed in NPRM DOCKET 98-93, sometimes called the "Negotiated Interference Proposal".
This new method considers terrain along the entire azimuth profile between a station and the interference source as opposed to the standard FCC method of using only the terrain between 2 and ten miles from the transmitter. (Whole mountains at 10.5 miles are missed under this method.) The PTP method is the brainchild of Harry Wong at the Commission. It uses Fresnel clearance as the basis for its primary calculations. The Commission proposes to allow the use of the PTP method in place of the FCC standard method for showing interference. Our early studies of this method indicate it is works nicely for rough terrain, but for smooth terrain the interference contour is seen to go far beyond the FCC standard method. In terms of service signal contour, use of this method under smooth terrain conditions will produce service contours that travel well beyond the FCC standard method. This means that many stations can use the method to more aggressively change the city of license for move-ins or to show the studio is within the city contour for studio moves.
The Commission has provided us with the FORTRAN code they use in the method and we have implemented within CONTOUR. Our experience with this code is that the contour distances are not duplicated exactly because of small differences in terrain databases their access routines and interpolation. We have learned that the Commission continues to use a pre-mid-eighties non-corrected terrain elevation database that has both metric and English values stored in it. The database used by V-Soft Communications is the principal USGS, 30 arc second database, TGP0050. This database has been corrected for terrain "holes" and badly enumerated lakes. The FCC has not as yet converted their 30-second terrain elevation database to the corrected database.
We recommend the use of the V-Soft Communications' 03 sec terrain elevation database for the highest accuracy in the implementation of the PTP method.
It should be noted that under the FCC's proposal the use of the PTP method is not allowed if it produces an interference signal contour distance that exceeds the FCC standard method using the same antenna height and power.
Since PTP calculations do not require an average elevation or HAAT these columns do not appear in the PTP study printouts. Further, the multiple column/signal value printouts are not available using the PTP method. However, multiple signal contour studies can be performed with the resulting distance to contour tables being viewed in sequence.