TH-D72A/E - N3UJJ

6 OPERATIONAL EXAMPLES OF APRSBy changing the value of TURN SLOPE, you can adjust how Corner Pegging responds as the mobilestation executes curves. When the value of TURN SLOPE is increased, a large heading angle changeis necessary to cause a position beacon transmission, especially at low speeds. When the value ofTURN SLOPE is reduced, the effect of speed on Corner Pegging is reduced, as the constant TURNANGLE becomes the controlling term in the equation. A value for TURN SLOPE of 110 (in units of 10degrees per mph) has been experimentally determined to be a good value for vehicles on typical roads.Corner Pegging Formula:TURN THRESHOLD = TURN ANGLE + 10 x TURN SLOPE / SPEEDThe above formula is based on the reality of how a mobile station executes turns: when traveling atslow speed, it can turn acute angles, but when traveling at high speeds, it turns only shallow angles.In other words, TURN THRESHOLD varies inversely with speed: at a low speed, the thresholdbecomes large, while at a high speed the threshold becomes small.To prevent the Corner Pegging beacon from transmitting too often and causing QRM, there is a timervalue called TURN TIME. The Corner Pegging position beacon is not transmitted until TURN TIMEseconds have elapsed since the previous beacon transmission, regardless of which method (CornerPegging or Variable Rate Beaconing) caused the previous beacon.Table 6-4 Conditions for Corner Pegging OperationOver HIGH SPEEDSpeedUnder HIGH SPEEDOver LOW SPEED(Only when HIGH SPEED ≥ LOW SPEED)Under LOW SPEEDCorner PeggingYesYesNoSpeedMenu ItemTable 6-5 Configuration ExampleTable 6-6 Corner Pegging Operation Example: (with TURN ANGLE = 28, TURN SLOPE = 26)TURN SLOPENote: When TURN THRESHOLD exceeds 120°, the value will be corrected to 120°.Configured ValueLOW SPEED 5TURN ANGLE 28°TURN SLOPETURN TIMETURN SLOPE/ Speed(Cut off after the decimal point) (1)26 (x10°/speed)30 secondsTURN ANGLE (2)TURN THRESHOLD (3)= (1) + (2)80 26 (x10) 3° 28° 31°70 26 (x10) 3° 28° 31°60 26 (x10) 4° 28° 32°50 26 (x10) 5° 28° 33°40 26 (x10) 6° 28° 34°30 26 (x10) 8° 28° 36°20 26 (x10) 13° 28° 41°10 26 (x10) 26° 28° 54°5 26 (x10) 52° 28° 80°2 26 (x10) 130° 28° 158° 120°TH-D72A/E CONTENTS 45From The N3UJJ.COM Document Library