diff --git a/src/kstsimulator.py b/src/kstsimulator.py
new file mode 100644
index 0000000..702599a
--- /dev/null
+++ b/src/kstsimulator.py
@@ -0,0 +1,528 @@
+import socket
+import threading
+import time
+import random
+import traceback
+from datetime import datetime, timedelta
+
+# =====================================
+# KST-Server-Simulator / DO5AMF
+# Usage: change configuration below and
+# run. Enter 127.0.0.1 : 23001 as a
+# target in KST4Contest or another
+# KST chat client.
+# =====================================
+
+# ==========================================
+# KONFIGURATION
+# ==========================================
+
+PORT = 23001
+HOST = '127.0.0.1'
+
+MSG_TO_USER_INTERVAL = 300.0 
+LOGIN_LOGOUT_INTERVAL = 60.0 
+KEEP_ALIVE_INTERVAL = 10.0 
+CLIENT_WARMUP_TIME = 5.0 
+
+PROB_INACTIVE = 0.10
+PROB_REACTIVE = 0.20
+
+# QSY Wahrscheinlichkeit (Wie oft wechselt ein User seine Frequenz?)
+# 0.05 = 5% Chance pro Nachricht, dass er die Frequenz ändert. Sonst bleibt er stabil.
+PROB_QSY = 0.05 
+
+BANDS_VHF = { "2m": (144.150, 144.400), "70cm": (432.100, 432.300) }
+BANDS_UHF = { "23cm": (1296.100, 1296.300), "3cm": (10368.100, 10368.250) }
+
+CHANNELS_SETUP = {
+    "2": {
+        "NAME": "144/432 MHz",
+        "NUM_USERS": 777,
+        "BANDS": BANDS_VHF,
+        "RATES": {"PUBLIC": 0.5, "DIRECTED": 3.0},
+        "PERMANENT": [
+            {"call": "DK5EW", "name": "Erwin", "loc": "JN47NX"},
+            {"call": "DL1TEST", "name": "TestOp", "loc": "JO50XX"}
+        ]
+    },
+    "3": {
+        "NAME": "Microwave",
+        "NUM_USERS": 333,
+        "BANDS": BANDS_UHF,
+        "RATES": {"PUBLIC": 0.2, "DIRECTED": 0.5},
+        "PERMANENT": [
+            {"call": "ON4KST", "name": "Alain", "loc": "JO20HI"},
+            {"call": "G4CBW", "name": "MwTest", "loc": "IO83AA"} 
+        ]
+    }
+}
+
+COUNTRY_MAPPING = {
+    "DL": ["JO", "JN"], "DA": ["JO", "JN"], "DF": ["JO", "JN"], "DJ": ["JO", "JN"], "DK": ["JO", "JN"], "DO": ["JO", "JN"],
+    "F": ["JN", "IN", "JO"], "G": ["IO", "JO"], "M": ["IO", "JO"], "2E": ["IO", "JO"],
+    "PA": ["JO"], "ON": ["JO"], "OZ": ["JO"], "SM": ["JO", "JP"], "LA": ["JO", "JP"],
+    "OH": ["KP"], "SP": ["JO", "KO"], "OK": ["JO", "JN"], "OM": ["JN", "KN"],
+    "HA": ["JN", "KN"], "S5": ["JN"], "9A": ["JN"], "HB9": ["JN"], "OE": ["JN"],
+    "I": ["JN", "JM"], "IK": ["JN", "JM"], "IU": ["JN", "JM"], "EA": ["IN", "IM"],
+    "CT": ["IM"], "EI": ["IO"], "GM": ["IO"], "GW": ["IO"], "YO": ["KN"],
+    "YU": ["KN"], "LZ": ["KN"], "SV": ["KM", "KN"], "UR": ["KO", "KN"],
+    "LY": ["KO"], "YL": ["KO"], "ES": ["KO"]
+}
+
+NAMES = ["Hans", "Peter", "Jo", "Alain", "Mike", "Sven", "Ole", "Jean", "Bob", "Tom", "Giovanni", "Mario", "Frank", "Steve", "Dave"]
+
+MSG_TEMPLATES_WITH_FREQ = [
+    "QSY {freq}", "PSE QSY {freq}", "Calling CQ on {freq}", "I am QRV on {freq}",
+    "Listening on {freq}", "Can you try {freq}?", "Signals strong on {freq}",
+    "Scattering on {freq}", "Please go to {freq}", "Running test on {freq}",
+    "Any takers for {freq}?", "Back to {freq}", "QRG {freq}?", "Aircraft scatter {freq}"
+]
+
+MSG_TEMPLATES_TEXT_ONLY = [
+    "TNX for QSO", "73 all", "Anyone for sked?", "Good conditions", 
+    "Nothing heard", "Rain scatter?", "Waiting for moonrise", "CQ Contest", 
+    "QRZ?", "My locator is {loc}", "Band is open"
+]
+
+REPLY_TEMPLATES = [
+    "Hello {user}, 599 here", "Rgr {user}, tnx for report", "Yes {user}, QSY?", 
+    "Sorry {user}, no copy", "Pse wait 5 min {user}", "Ok {user}, 73",
+    "Locator is {loc}", "Go to {freq} please", "Rgr {user}, gl"
+]
+
+# ==========================================
+# CLIENT WRAPPER
+# ==========================================
+
+class ConnectedClient:
+    def __init__(self, sock, addr):
+        self.sock = sock
+        self.addr = addr
+        self.call = f"GUEST_{random.randint(1000,9999)}"
+        self.channels = {"2"} 
+        self.login_time = time.time()
+        self.lock = threading.Lock() 
+        
+    def send_safe(self, data_str):
+        if not data_str: return True
+        with self.lock:
+            try:
+                self.sock.sendall(data_str.encode('latin-1', errors='replace'))
+                return True
+            except:
+                return False
+
+    def close(self):
+        try: self.sock.close()
+        except: pass
+
+# ==========================================
+# LOGIK KLASSEN
+# ==========================================
+
+class MessageFactory:
+    @staticmethod
+    def get_stable_frequency(user, band_name, min_f, max_f):
+        """Liefert eine stabile Frequenz für diesen User auf diesem Band"""
+        # Wenn noch keine Frequenz da ist ODER Zufall zuschlägt (QSY)
+        if band_name not in user['freqs'] or random.random() < PROB_QSY:
+            freq_val = round(random.uniform(min_f, max_f), 3)
+            user['freqs'][band_name] = f"{freq_val:.3f}"
+            
+        return user['freqs'][band_name]
+
+    @staticmethod
+    def get_chat_message(bands_config, user):
+        try:
+            # Entscheidung: Text mit Frequenz oder ohne?
+            if random.random() < 0.7:
+                # Wähle zufälliges Band aus den verfügbaren
+                band_name = random.choice(list(bands_config.keys()))
+                min_f, max_f = bands_config[band_name]
+                
+                # Hole STABILE Frequenz für diesen User
+                freq_str = MessageFactory.get_stable_frequency(user, band_name, min_f, max_f)
+                
+                return random.choice(MSG_TEMPLATES_WITH_FREQ).format(freq=freq_str)
+            else:
+                return random.choice(MSG_TEMPLATES_TEXT_ONLY).format(loc=user['loc'])
+        except: return "TNX 73"
+
+    @staticmethod
+    def get_reply_msg(bands, target_call, my_loc):
+        try:
+            tmpl = random.choice(REPLY_TEMPLATES)
+            freq_str = "QSY?"
+            # Bei Replies simulieren wir oft nur "QSY?" ohne konkrete Frequenz,
+            # oder nutzen eine zufällige, da der Kontext fehlt.
+            if "{freq}" in tmpl and bands:
+                band_name = random.choice(list(bands.keys()))
+                min_f, max_f = bands[band_name]
+                freq_str = f"{round(random.uniform(min_f, max_f), 3):.3f}"
+            return tmpl.format(user=target_call, loc=my_loc, freq=freq_str)
+        except: return "TNX 73"
+
+class UserFactory:
+    registry = {} 
+
+    @classmethod
+    def get_or_create_user(cls, channel_id, current_channel_users):
+        # 1. Reuse existing
+        candidates = [u for call, u in cls.registry.items() if call not in current_channel_users]
+        if candidates and random.random() < 0.5:
+            return random.choice(candidates)
+            
+        # 2. Create new
+        return cls._create_new_unique_user(channel_id, current_channel_users)
+
+    @classmethod
+    def _create_new_unique_user(cls, channel_id, current_channel_users):
+        while True:
+            prefix = random.choice(list(COUNTRY_MAPPING.keys()))
+            num = random.randint(0, 9)
+            suffix = "".join(random.choices("ABCDEFGHIJKLMNOPQRSTUVWXYZ", k=random.randint(1,3)))
+            call = f"{prefix}{num}{suffix}"
+            
+            if call in current_channel_users: continue
+            if call in cls.registry: return cls.registry[call]
+                
+            valid_grids = COUNTRY_MAPPING[prefix] 
+            grid_prefix = random.choice(valid_grids)
+            sq_num = f"{random.randint(0,99):02d}"
+            sub = "".join(random.choices("ABCDEFGHIJKLMNOPQRSTUVWXYZ", k=2))
+            loc = f"{grid_prefix}{sq_num}{sub}"
+            
+            name = random.choice(NAMES)
+            rand = random.random()
+            if rand < PROB_INACTIVE: role = "INACTIVE"
+            elif rand < (PROB_INACTIVE + PROB_REACTIVE): role = "REACTIVE"
+            else: role = "ACTIVE"
+            
+            # Neu V31: Frequenz-Gedächtnis
+            user_data = {
+                "call": call, 
+                "name": name, 
+                "loc": loc, 
+                "role": role, 
+                "freqs": {} # Speicher für { '2m': '144.300' }
+            }
+            
+            cls.registry[call] = user_data
+            return user_data
+
+    @classmethod
+    def register_permanent(cls, user_data):
+        # Sicherstellen, dass auch Permanent User Freq-Memory haben
+        if "freqs" not in user_data:
+            user_data["freqs"] = {}
+        cls.registry[user_data['call']] = user_data
+
+# ==========================================
+# CHANNEL INSTANCE
+# ==========================================
+
+class ChannelInstance:
+    def __init__(self, cid, config, server):
+        self.id = cid
+        self.config = config
+        self.server = server
+        
+        self.users_pool = []
+        self.online_users = {} 
+        self.history_chat = []
+        
+        self.last_pub = time.time()
+        self.last_dir = time.time()
+        self.last_me = time.time()
+        self.last_login = time.time()
+        
+        self.rate_pub = 1.0 / config["RATES"]["PUBLIC"]
+        self.rate_dir = 1.0 / config["RATES"]["DIRECTED"]
+        
+        self._init_data()
+        
+    def _init_data(self):
+        print(f"[*] Init Channel {self.id} ({self.config['NAME']})...")
+        
+        for u in self.config["PERMANENT"]:
+            u_full = u.copy()
+            u_full["role"] = "ACTIVE"
+            UserFactory.register_permanent(u_full)
+            self.online_users[u['call']] = u_full
+
+        for _ in range(self.config["NUM_USERS"]):
+            new_u = UserFactory.get_or_create_user(self.id, self.online_users.keys())
+            self.users_pool.append(new_u)
+            
+        fill = int(self.config["NUM_USERS"] * 0.9)
+        for i in range(fill):
+            u = self.users_pool[i]
+            if u['call'] not in self.online_users:
+                self.online_users[u['call']] = u
+        
+        print(f"[*] Channel {self.id} ready: {len(self.online_users)} Users.")
+        self._prefill_history()
+        
+    def _prefill_history(self):
+        actives = [u for u in self.online_users.values() if u['role'] == "ACTIVE"]
+        if not actives: return
+        start = datetime.now() - timedelta(minutes=15)
+        for i in range(30):
+            msg_time = start + timedelta(seconds=i*30)
+            ts = str(int(msg_time.timestamp()))
+            sender = random.choice(actives)
+            if i % 2 == 0:
+                text = MessageFactory.get_chat_message(self.config["BANDS"], sender)
+                frame = f"CH|{self.id}|{ts}|{sender['call']}|{sender['name']}|0|{text}|0|\r\n"
+            else:
+                target = random.choice(list(self.online_users.values()))
+                text = MessageFactory.get_reply_msg(self.config["BANDS"], target['call'], sender['loc'])
+                frame = f"CH|{self.id}|{ts}|{sender['call']}|{sender['name']}|0|{text}|{target['call']}|\r\n"
+            self.history_chat.append(frame)
+
+    def tick(self, now):
+        actives = [u for u in self.online_users.values() if u['role'] == "ACTIVE"]
+        if not actives: return
+        
+        # PUBLIC
+        if now - self.last_pub > self.rate_pub:
+            self.last_pub = now
+            u = random.choice(actives)
+            # V31: Nutzt jetzt get_chat_message, das das Freq-Memory abfragt
+            text = MessageFactory.get_chat_message(self.config["BANDS"], u)
+            ts = str(int(now))
+            frame = f"CH|{self.id}|{ts}|{u['call']}|{u['name']}|0|{text}|0|\r\n"
+            self._add_hist(frame)
+            self.server.broadcast_to_channel(self.id, frame)
+            
+        # DIRECTED
+        if now - self.last_dir > self.rate_dir:
+            self.last_dir = now
+            if len(actives) > 5:
+                u1 = random.choice(actives)
+                u2 = random.choice(list(self.online_users.values()))
+                if u1 != u2:
+                    if random.random() < 0.5:
+                        # Auch hier Frequenzstabilität beachten
+                        text = MessageFactory.get_chat_message(self.config["BANDS"], u1)
+                    else:
+                        text = MessageFactory.get_reply_msg(self.config["BANDS"], u2['call'], u1['loc'])
+                    ts = str(int(now))
+                    frame = f"CH|{self.id}|{ts}|{u1['call']}|{u1['name']}|0|{text}|{u2['call']}|\r\n"
+                    self.server.broadcast_to_channel(self.id, frame)
+                    if u2['role'] != "INACTIVE":
+                        threading.Thread(target=self._schedule_reply, args=(u2['call'], u1['call']), daemon=True).start()
+
+        # MSG TO YOU
+        if now - self.last_me > MSG_TO_USER_INTERVAL:
+            self.last_me = now
+            target_client = self.server.get_random_subscriber(self.id)
+            if target_client and actives:
+                if not target_client.call.startswith("GUEST"):
+                    sender = random.choice(actives)
+                    text = MessageFactory.get_chat_message(self.config["BANDS"], sender)
+                    print(f"[SIM Ch{self.id}] MSG TO YOU ({target_client.call})")
+                    self.process_msg(sender['call'], sender['name'], text, target_client.call)
+
+        # LOGIN/LOGOUT
+        if now - self.last_login > LOGIN_LOGOUT_INTERVAL:
+            self.last_login = now
+            if random.choice(['IN', 'OUT']) == 'OUT' and len(self.online_users) > 20:
+                cands = [c for c in self.online_users if c not in [p['call'] for p in self.config["PERMANENT"]]]
+                if cands:
+                    l = random.choice(cands)
+                    del self.online_users[l]
+                    self.server.broadcast_to_channel(self.id, f"UR6|{self.id}|{l}|\r\n")
+            else:
+                candidates = [u for u in self.users_pool if u['call'] not in self.online_users]
+                if candidates:
+                    n = random.choice(candidates)
+                    self.online_users[n['call']] = n
+                    self.server.broadcast_to_channel(self.id, f"UA5|{self.id}|{n['call']}|{n['name']}|{n['loc']}|2|\r\n")
+
+    def process_msg(self, sender, name, text, target):
+        ts = str(int(time.time()))
+        frame = f"CH|{self.id}|{ts}|{sender}|{name}|0|{text}|{target}|\r\n"
+        if target == "0": self._add_hist(frame)
+        self.server.broadcast_to_channel(self.id, frame)
+        if target in self.online_users:
+            threading.Thread(target=self._schedule_reply, args=(target, sender), daemon=True).start()
+            
+    def _schedule_reply(self, sim_sender, real_target):
+        if sim_sender not in self.online_users: return
+        u = self.online_users[sim_sender]
+        if u['role'] == "INACTIVE": return
+        
+        time.sleep(random.uniform(2.0, 5.0))
+        if sim_sender in self.online_users:
+            text = MessageFactory.get_reply_msg(self.config["BANDS"], real_target, u['loc'])
+            ts = str(int(time.time()))
+            
+            if self.server.is_real_user(real_target):
+                print(f"[REPLY Ch{self.id}] {sim_sender} -> {real_target}")
+            
+            frame = f"CH|{self.id}|{ts}|{sim_sender}|{u['name']}|0|{text}|{real_target}|\r\n"
+            self.server.broadcast_to_channel(self.id, frame)
+
+    def _add_hist(self, frame):
+        self.history_chat.append(frame)
+        if len(self.history_chat) > 50: self.history_chat.pop(0)
+
+    def get_full_init_blob(self):
+        blob = ""
+        for u in self.online_users.values():
+            blob += f"UA0|{self.id}|{u['call']}|{u['name']}|{u['loc']}|0|\r\n"
+        for h in self.history_chat: blob += h
+        blob += f"UE|{self.id}|{len(self.online_users)}|\r\n"
+        return blob.encode('latin-1', errors='replace')
+
+# ==========================================
+# SERVER
+# ==========================================
+
+class KSTServerV31:
+    def __init__(self):
+        self.lock = threading.Lock()
+        self.running = True
+        self.clients = {} 
+        self.channels = {}
+        
+        for cid, cfg in CHANNELS_SETUP.items():
+            self.channels[cid] = ChannelInstance(cid, cfg, self)
+            
+    def start(self):
+        threading.Thread(target=self._sim_loop, daemon=True).start()
+        
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        try:
+            s.bind((HOST, PORT))
+            s.listen(5)
+            s.settimeout(1.0)
+            print(f"[*] ON4KST V31 (Stable Frequencies) running on {HOST}:{PORT}")
+            
+            while self.running:
+                try:
+                    sock, addr = s.accept()
+                    print(f"[*] CONNECT: {addr}")
+                    threading.Thread(target=self._handle_client, args=(sock,), daemon=True).start()
+                except socket.timeout: continue
+                except OSError: break
+        except KeyboardInterrupt:
+            print("\n[!] Stop.")
+        finally:
+            self.running = False
+            try: s.close()
+            except: pass
+            
+    def _handle_client(self, sock):
+        client_obj = ConnectedClient(sock, None)
+        with self.lock:
+            self.clients[sock] = client_obj
+            
+        buffer = ""
+        try:
+            while self.running:
+                try: data = sock.recv(2048)
+                except: break
+                if not data: break
+                
+                buffer += data.decode('latin-1', errors='replace')
+                while '\n' in buffer:
+                    line, buffer = buffer.split('\n', 1)
+                    line = line.strip()
+                    if not line: continue
+                    
+                    parts = line.split('|')
+                    cmd = parts[0]
+                    
+                    if cmd == 'LOGIN' or cmd == 'LOGINC':
+                        if len(parts) > 1:
+                            client_obj.call = parts[1].strip().upper()
+                            print(f"[LOGIN] {client_obj.call} (Ch 2)")
+                        
+                        client_obj.send_safe(f"LOGSTAT|100|2|PySimV31|KEY|Conf|3|\r\n")
+                        if cmd == 'LOGIN': 
+                            self._send_channel_init(client_obj, "2")
+                            
+                    elif cmd == 'SDONE':
+                        self._send_channel_init(client_obj, "2")
+                        
+                    elif cmd.startswith('ACHAT'):
+                        if len(parts) >= 2:
+                            new_chan = parts[1]
+                            if new_chan in self.channels:
+                                client_obj.channels.add(new_chan)
+                                print(f"[ACHAT] {client_obj.call} -> Ch {new_chan}")
+                                self._send_channel_init(client_obj, new_chan)
+                                
+                    elif cmd == 'MSG':
+                        if len(parts) >= 4:
+                            cid = parts[1]
+                            target = parts[2]
+                            text = parts[3]
+                            if text.lower().startswith("/cq"):
+                                spl = text.split(' ', 2)
+                                if len(spl) >= 3:
+                                    target = spl[1]; text = spl[2]
+                            if cid in self.channels:
+                                self.channels[cid].process_msg(client_obj.call, "Me", text, target)
+                                
+                    elif cmd == 'CK': pass
+        except Exception as e:
+            print(f"[!] Err: {e}")
+        finally:
+            with self.lock:
+                if sock in self.clients: del self.clients[sock]
+            client_obj.close()
+            
+    def _send_channel_init(self, client_obj, cid):
+        if cid in self.channels:
+            full_blob = self.channels[cid].get_full_init_blob()
+            client_obj.send_safe(full_blob.decode('latin-1'))
+
+    def broadcast_to_channel(self, cid, frame):
+        now = time.time()
+        with self.lock:
+            targets = list(self.clients.values())
+            
+        for c in targets:
+            if cid in c.channels:
+                if now - c.login_time > CLIENT_WARMUP_TIME:
+                    c.send_safe(frame)
+                
+    def get_random_subscriber(self, cid):
+        with self.lock:
+            subs = [c for c in self.clients.values() if cid in c.channels and not c.call.startswith("GUEST")]
+        return random.choice(subs) if subs else None
+        
+    def is_real_user(self, call):
+        with self.lock:
+            for c in self.clients.values():
+                if c.call.upper() == call.upper() and not c.call.startswith("GUEST"):
+                    return True
+        return False
+
+    def _sim_loop(self):
+        print("[*] Sim Loop running...")
+        last_ka = time.time()
+        while self.running:
+            now = time.time()
+            time.sleep(0.02)
+            
+            for c in self.channels.values():
+                c.tick(now)
+            
+            if now - last_ka > KEEP_ALIVE_INTERVAL:
+                last_ka = now
+                self.broadcast_global("CK|\r\n") 
+               
+    def broadcast_global(self, frame):
+        with self.lock:
+            targets = list(self.clients.values())
+        for c in targets:
+            c.send_safe(frame)
+
+if __name__ == '__main__':
+    KSTServerV31().start()
\ No newline at end of file