diff --git a/codebook.py b/codebook.py
deleted file mode 100644
index a274881..0000000
--- a/codebook.py
+++ /dev/null
@@ -1,18 +0,0 @@
-# codebook.py
-import numpy as np
-
-def generate_Br(r):
-    if r == 0:
-        return np.array([[1]])
-    M = generate_Br(r - 1)
-    top = np.hstack((M, M))
-    bottom = np.hstack((M, -M))
-    return np.vstack((top, bottom))
-
-def construct_codebook(r, Eb):
-    Br = generate_Br(r)
-    n = 2 * Br.shape[1]  # Since codeword is [Br | Br]
-    m = Br.shape[0]      # Number of messages
-    alpha = Eb * 2 / ((1 + 10) * n)  # G=10
-    codebook = np.sqrt(alpha) * np.hstack((Br, Br))
-    return codebook, n, m, alpha
\ No newline at end of file
diff --git a/evaluate_zero_error_ratio.py b/evaluate_zero_error_ratio.py
deleted file mode 100644
index 986c74f..0000000
--- a/evaluate_zero_error_ratio.py
+++ /dev/null
@@ -1,54 +0,0 @@
-# evaluate_zero_error_ratio.py
-
-import argparse
-import numpy as np
-from encoder import text_to_signal
-from decoder import signal_to_text
-from channel import channel
-
-def zero_error_ratio(message: str, r: int, Eb: float, n_runs: int) -> float:
-    """
-    Runs the encode–channel–decode pipeline n_runs times on the same message,
-    and returns the fraction of runs with 0 character errors.
-    """
-    zero_count = 0
-    for _ in range(n_runs):
-        # encode
-        x, codebook = text_to_signal(message, r=r, Eb=Eb)
-        # pass through channel
-        y = channel(x)
-        # decode
-        decoded = signal_to_text(y, codebook, r=r)
-        # count errors
-        errors = sum(1 for a, b in zip(message, decoded) if a != b)
-        if errors == 0:
-            zero_count += 1
-    return zero_count / n_runs
-
-if __name__ == "__main__":
-    parser = argparse.ArgumentParser(
-        description="Estimate the zero-error run ratio over n trials."
-    )
-    parser.add_argument(
-        "--message", type=str, required=True,
-        help="The 40-char message to test."
-    )
-    parser.add_argument(
-        "--r", type=int, default=6,
-        help="Codebook parameter r (default: 6)."
-    )
-    parser.add_argument(
-        "--Eb", type=float, default=3.0,
-        help="Energy per bit Eb (default: 3)."
-    )
-    parser.add_argument(
-        "--n", type=int, default=1000,
-        help="Number of runs (default: 1000)."
-    )
-    args = parser.parse_args()
-
-    if len(args.message) != 40:
-        raise ValueError("Message must be exactly 40 characters long.")
-
-    ratio = zero_error_ratio(args.message, args.r, args.Eb, args.n)
-    print(f"Zero-error runs: {ratio:.3%} ({ratio:.4f} of {args.n})")
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..34f2bb3
--- /dev/null
+++ b/main.py
@@ -0,0 +1,58 @@
+# main.py
+#!/usr/bin/env python3
+import argparse
+import socket
+import numpy as np
+import channel_helper as ch
+from encoder import make_codebook, encode_message
+from decoder import decode_blocks, count_errors
+from channel import channel as external_channel
+
+
+def send_and_recv(x: np.ndarray, host: str, port: int) -> np.ndarray:
+    """Send samples x to server and receive output via TCP"""
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+        sock.connect((host, port))
+        header = b'0' + b'dUV'
+        ch.send_msg(sock, header, x)
+        _, Y = ch.recv_msg(sock)
+    return Y
+
+
+def main():
+    p = argparse.ArgumentParser(description="PDC Tx/Rx local or server")
+    p.add_argument("--message", required=True, help="40-character message to send")
+    p.add_argument("--srv_hostname", help="Server hostname")
+    p.add_argument("--srv_port", type=int, help="Server port")
+    p.add_argument("--local", action='store_true', help="Use local channel simulation")
+    args = p.parse_args()
+
+    msg = args.message
+    if len(msg) != 40:
+        raise ValueError("Message must be exactly 40 characters.")
+    num_blocks = len(msg)
+    C = make_codebook(r=5, num_blocks=num_blocks, margin=0.95)
+    x = encode_message(msg, C)
+    print(f"→ Total samples = {x.size}, total energy = {np.sum(x*x):.1f}")
+
+    if args.local:
+        print("-- Local simulation mode --")
+        Y = external_channel(x)
+    else:
+        if not args.srv_hostname or not args.srv_port:
+            raise ValueError("Must specify --srv_hostname and --srv_port unless --local")
+        Y = send_and_recv(x, args.srv_hostname, args.srv_port)
+
+    msg_hat = decode_blocks(Y, C)
+    print(f"↓ Decoded message: {msg_hat}")
+
+    errors = count_errors(msg, msg_hat)
+    print(f"Errors: {len(errors)} / {len(msg)} characters differ")
+    if errors:
+        for i, o, e in errors:
+            print(f"  Pos {i}: sent '{o}' but got '{e}'")
+    else:
+        print("✔️  No decoding errors!")
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
diff --git a/performance_local.py b/performance_local.py
new file mode 100644
index 0000000..8bac46f
--- /dev/null
+++ b/performance_local.py
@@ -0,0 +1,37 @@
+# performance_local.py
+#!/usr/bin/env python3
+import argparse
+import numpy as np
+import random
+from encoder import make_codebook, encode_message, ALPHABET
+from decoder import decode_blocks, count_errors
+from channel import channel
+
+
+def random_message(length):
+    return ''.join(random.choice(ALPHABET) for _ in range(length))
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Monte Carlo evaluation over local channel")
+    parser.add_argument("--num", type=int, required=True, help="Number of trials")
+    parser.add_argument("--r", type=int, default=5, help="Hadamard order (default 5)")
+    args = parser.parse_args()
+
+    num_trials = args.num
+    successes = 0
+
+    for _ in range(num_trials):
+        msg = random_message(40)
+        C = make_codebook(r=args.r, num_blocks=len(msg))
+        x = encode_message(msg, C)
+        Y = channel(x)
+        msg_hat = decode_blocks(Y, C)
+        if msg_hat == msg:
+            successes += 1
+
+    ratio = successes / num_trials
+    print(f"Correctly decoded messages: {successes}/{num_trials} ({ratio:.2%})")
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
diff --git a/utils.py b/utils.py
deleted file mode 100644
index dadf44b..0000000
--- a/utils.py
+++ /dev/null
@@ -1,11 +0,0 @@
-alphabet = list("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 .")
-alphabet_size = len(alphabet)
-char_to_index = {c: i for i, c in enumerate(alphabet)}
-index_to_char = {i: c for i, c in enumerate(alphabet)}
-
-import numpy as np
-
-def normalize_energy(signal, energy_limit=2000):
-    norm = np.sqrt(np.sum(signal ** 2))
-    scale = np.sqrt(energy_limit) / norm
-    return signal * scale
\ No newline at end of file