diff --git a/tnc/modem.py b/tnc/modem.py
index a443dfe6..e696680a 100644
--- a/tnc/modem.py
+++ b/tnc/modem.py
@@ -334,8 +334,6 @@ class RF:
         while True:
             threading.Event().wait(0.01)
 
-
-            # -----write
             if len(self.modoutqueue) > 0 and not self.mod_out_locked:
                 data_out = self.modoutqueue.popleft()
                 self.tci_module.push_audio(data_out)
diff --git a/tnc/tci.py b/tnc/tci.py
index 849e696c..424c8f3f 100644
--- a/tnc/tci.py
+++ b/tnc/tci.py
@@ -4,6 +4,7 @@
 import structlog
 import threading
 import websocket
+import numpy as np
 from queues import AUDIO_TRANSMIT_QUEUE, AUDIO_RECEIVED_QUEUE
 
 """
@@ -35,6 +36,11 @@ class TCI:
         # flag if we're receiving a tx_chrono
         self.tx_chrono = False
 
+        # audio related parameters, will be updated by tx chrono
+        self.sample_rate = None
+        self.format = None
+        self.codec = None
+        self.audio_length = None
 
 
     def connect(self):
@@ -66,10 +72,30 @@ class TCI:
 
         # tx chrono frame
         if len(message) in {64}:
+            receiver = message[:4]
+            sample_rate = int.from_bytes(message[4:8], "little")
+            format = int.from_bytes(message[8:12], "little")
+            codec = int.from_bytes(message[12:16], "little")
+            crc = int.from_bytes(message[16:20], "little")
+            audio_length = int.from_bytes(message[20:24], "little")
             type = int.from_bytes(message[24:28], "little")
+            channel = int.from_bytes(message[28:32], "little")
+            reserved1 = int.from_bytes(message[32:36], "little")
+            reserved2 = int.from_bytes(message[36:40], "little")
+            reserved3 = int.from_bytes(message[40:44], "little")
+            reserved4 = int.from_bytes(message[44:48], "little")
+            reserved5 = int.from_bytes(message[48:52], "little")
+            reserved6 = int.from_bytes(message[52:56], "little")
+            reserved7 = int.from_bytes(message[56:60], "little")
+            reserved8 = int.from_bytes(message[60:64], "little")
             if type == 3:
                 self.tx_chrono = True
 
+                self.sample_rate = sample_rate
+                self.format = format
+                self.codec = codec
+                self.audio_length = audio_length
+
         # audio frame
         if len(message) in {576, 2464, 4160}:
             # audio received
@@ -114,8 +140,8 @@ class TCI:
         )
 
     def push_audio(self, data_out):
+        print(data_out)
 
-        audio = bytearray(4096 + 64)
         """
         # audio[:4] = receiver.to_bytes(4,byteorder='little', signed=False)
         audio[4:8] = sample_rate.to_bytes(4, byteorder='little', signed=False)
@@ -134,7 +160,30 @@ class TCI:
         audio[56:60] = reserved7.to_bytes(4, byteorder='little', signed=False)
         audio[60:64] = reserved8.to_bytes(4, byteorder='little', signed=False)
         """
-        self.ws.send(audio, websocket.ABNF.OPCODE_BINARY)
+
+        print(self.audio_length)
+        print(self.tx_chrono)
+        print(self.format)
+        print(self.codec)
+
+        if self.tx_chrono:
+            # dummy for now ...
+            audio = bytearray(4096 + 64)
+
+            # generate sine wave
+            rate = 8000  # samples per second
+            T = 3  # sample duration (seconds)
+            # n = int(rate*T)        # number of samples
+            n = 1200
+            t = np.arange(n) / rate  # grid of time values
+
+            f = 440.0  # sound frequency (Hz)
+            x = np.sin(2 * np.pi * f * t)
+
+            # print(len(x))
+            audio[64:] = bytes(x)
+            audio[24:28] = int(2).to_bytes(4, byteorder='little', signed=True)
+            self.ws.send(audio, websocket.ABNF.OPCODE_BINARY)
 
     def set_ptt(self, state):
         if state: