Willkommen! Let me explain to you what a Geschwindigkeitsprüfabschnitt is and how the Geschwindigkeitsüberwachung is executed with Lf-Boards and PZB. I assume you know all trackside signals aswell as how to use PZB. GPA/GU is used with Lf6's, morpeth boards. If the Lf6 is showing 8 or 9, sometimes even with 7, the signal will have an active 1000Hz GPA. What does this mean? This means, if you're exceeding the speed by more the 15%, you'll need to acknowledge and will get a 1000Hz restriction. Notice that this is not a classic 1000Hz magnet - it's not always active. If the Lf6 is showing 10 to 14, you'll encounter a 2000Hz GU. What does this mean you ask? A 500Hz-distance before the Lf7, that is speed limit board, or about 700 meters after the Lf6, you'll encounter a 2000Hz, yes you read that correctly 2000Hz, magnet. If exceeding the speed by more than 15%, you'll instantly get a 2000Hz Zwangsbremsung. This needn't be acknowledged, but it hertz you. (Sorry Matt for abusing your joke) VERY IMPORTANT is, that these ONLY apply to Lf boards as described. These DO NOT apply for Zs boards. Also notice, the MFD (LCD display) will report as reason for Zwangsbremsung a SPAD if you have failed a 2000Hz GU: 2000Hz-Beeinflussung! The GPA will be reported with Geschwindigkeitsüberschreitung! or WT nicht zeitgerecht betätigt! if you are speeding or if you forgot to acknowledge respectively. As of now, in RSN all Zs boards below 100kph need to be acknowledged. This is correct. However, in RSN you also have to acknowledge all Lf6's below 100kph. This is not always correct. Also, the 2000Hz is missing. I think I have made clear how this should be implemented. This is not a major mistake, however, I kindly ask DTG to keep the flaw in mind and to fix it, when the time comes. Hope I gave you an interesting insight in the intricacies of PZB Cheers, Prof PS: Complete RSN Bug report coming soon. This guide is a part of my Guides-Megaproject. More will come. PPS: Here are speeds and the 15% gap. The Distance X is the distance between 2000Hz and speed board.