diff --git a/network_backend.py b/network_backend.py
index ae69112..c0ff904 100644
--- a/network_backend.py
+++ b/network_backend.py
@@ -16,7 +16,7 @@ from nmea.GGA import Gga
 from nmea.RMC import Rmc
 from threading import Thread
 from queue import Queue
-
+from ubx.ubx import frame_create
 
 class NetworkBackend(ABackend):
 	def __init__(self, servers: list[dict]):
@@ -145,9 +145,10 @@ if __name__ == "__main__":
 			Gga(grm, 'GN'),
 		]
 		ubx_rx_list = [
-			UbxReceiver('UBX-NAV-SIG', 0x01, 0x43),
+#			UbxReceiver('UBX-NAV-SIG', 0x01, 0x43),
 			UbxReceiver('UBX-ACK-ACK', 0x05, 0x01),
 			UbxReceiver('UBX-ACK-NACK', 0x05, 0x00),
+			UbxReceiver('default'),
 		]
 
 		# Topology
@@ -190,7 +191,9 @@ if __name__ == "__main__":
 	while True:
 		try:
 			for grm in [" neo-f9p", "zed-x20p"]:
-				transceiver[grm].send(b'Hallo')
+				# Poll UBX-NAV-CLOCK (0x01 0x22)
+				frame = frame_create(0x01, 0x22, b'')
+				transceiver[grm].send(frame)
 		except ValueError:
 			break
 
diff --git a/receiver/ubx_receiver.py b/receiver/ubx_receiver.py
index aea8171..4170ddb 100644
--- a/receiver/ubx_receiver.py
+++ b/receiver/ubx_receiver.py
@@ -3,7 +3,7 @@ from msg_sink import MsgSink
 from ubx.ubx import frame_parse, frame_parse_hdr
 
 class UbxReceiver(MsgSink):
-	def __init__(self, name: str, mclass: int, mid: int):
+	def __init__(self, name: str, mclass: int|None = None, mid: int|None = None):
 		MsgSink.__init__(self)
 		self.name = name
 		self.mclass = mclass
@@ -16,5 +16,8 @@ class UbxReceiver(MsgSink):
 	def is_msg(self, msg: MsgContainer):
 		hdr = frame_parse_hdr(msg.data)
 		if hdr is not None:
-			return self.mclass == hdr.mclass and self.mid == hdr.mid
+			if self.mclass is not None and self.mid is not None:
+				return self.mclass == hdr.mclass and self.mid == hdr.mid
+			else:
+				return True
 		return False