diff --git a/amodem/qam.py b/amodem/qam.py
index 0b451a2..8842029 100644
--- a/amodem/qam.py
+++ b/amodem/qam.py
@@ -7,7 +7,7 @@ class QAM(object):
     buf_size = 16
 
     def __init__(self, symbols):
-        self._enc = {}
+        self.encode_map = {}
         symbols = np.array(list(symbols))
         bits_per_symbol = np.log2(len(symbols))
         bits_per_symbol = np.round(bits_per_symbol)
@@ -17,43 +17,26 @@ class QAM(object):
 
         for i, v in enumerate(symbols):
             bits = [int(i & (1 << j) != 0) for j in range(bits_per_symbol)]
-            self._enc[tuple(bits)] = v
+            self.encode_map[tuple(bits)] = v
 
-        self._dec = {v: k for k, v in self._enc.items()}
         self.symbols = symbols
         self.bits_per_symbol = bits_per_symbol
 
-        reals = np.array(list(sorted(set(symbols.real))))
-        imags = np.array(list(sorted(set(symbols.imag))))
-
-        _mean = lambda u: float(sum(u))/len(u) if len(u) else 1.0
-        self.real_factor = 1.0 / _mean(np.diff(reals))
-        self.imag_factor = 1.0 / _mean(np.diff(imags))
-        self.bias = reals[0] + 1j * imags[0]
-
-        self.symbols_map = {}
-        for S in symbols:
-            s = S - self.bias
-            real_index = round(s.real * self.real_factor)
-            imag_index = round(s.imag * self.imag_factor)
-            self.symbols_map[real_index + 1j * imag_index] = (S, self._dec[S])
-        self.real_max = max(k.real for k in self.symbols_map)
-        self.imag_max = max(k.imag for k in self.symbols_map)
+        bits_map = {symbol: bits for bits, symbol in self.encode_map.items()}
+        self.decode_list = [(s, bits_map[s]) for s in self.symbols]
 
     def encode(self, bits):
         for bits_tuple in common.iterate(bits, self.bits_per_symbol, tuple):
-            yield self._enc[bits_tuple]
+            yield self.encode_map[bits_tuple]
 
     def decode(self, symbols, error_handler=None):
-        symbols_map = self.symbols_map
+        symbols_vec = self.symbols
+        _dec = self.decode_list
         for syms in common.iterate(symbols, self.buf_size, truncate=False):
-            s = syms - self.bias
-            real_index = np.clip(s.real * self.real_factor, 0, self.real_max)
-            imag_index = np.clip(s.imag * self.imag_factor, 0, self.imag_max)
-
-            keys = np.round(real_index + 1j * imag_index)
-            for key, received in zip(keys, syms):
-                decoded_symbol, bits = symbols_map[key]
+            for received in syms:
+                error = np.abs(symbols_vec - received)
+                index = np.argmin(error)
+                decoded, bits = _dec[index]
                 if error_handler:
-                    error_handler(received=received, decoded=decoded_symbol)
+                    error_handler(received=received, decoded=decoded)
                 yield bits