The interactive Performance workspace, the printable Path Survey report, and the Microsoft Word (.rtf) export all share a single unified link-budget engine aligned with Pathloss 5 and ITU-R recommendations.
For imperial paths in statute miles, Spanline uses the standard Pathloss 5 mile constant (96.6):
FSL (dB) = 96.6 + 20·log10(fGHz) + 20·log10(dmiles)
Path distance is evaluated from the unrounded WGS84 Vincenty geodesic distance prior to taking the logarithm (or with the metric constant 92.45 for distances in kilometres).
Received signal level (RSL) equals transmit power plus transmit and receive antenna gains, minus radome, antenna orientation, free-space loss, ITU-R P.676 atmospheric gaseous absorption, optional ITU-R P.526-15 obstruction diffraction loss (Delta-Bullington, Deygout, Bullington, or Single Knife-Edge), and the transmission line, connector, branching, filter, and miscellaneous losses at each terminal. Thermal fade margin equals the received signal level minus the active receiver threshold.
Oxygen and water-vapor specific attenuation follow ITU-R P.676 across the full microwave and millimeter-wave spectrum. On the Byhalia (College & Bethel) 11 GHz reference hop, total atmospheric absorption is 0.088 dB.
For radios with adaptive modulation profiles (up to 10 ACM modes), each mode's operating threshold incorporates the configured ATPC step where applicable, while keeping the 10−6 BER reference threshold in its dedicated column. Imported Pathloss 5 .pl5 files preserve their stored thresholds directly without double-applying an offset.
Multipath fading and annual availability support both North American Vigants–Barnett (including Pathloss 5's intervisible 50-point sea-level terrain roughness algorithm with central-80% fallback and ITU-R P.1510-0 bilinear annual temperature interpolation) and ITU-R P.530-17. Rain outage supports both the Crane empirical model (with 200+ North American city rain-rate curves) and ITU-R P.837 / P.838. Annual availability is reported to five decimal places.
On the Byhalia (College & Bethel) reference .pl5 path, Spanline produces a free-space loss of 127.83 dB, net path loss of 58.32 dB, receive signal level of −31.32 dBm, and thermal fade margin of 17.28 dB—matching Pathloss 5 to the hundredth of a decibel.