diff --git a/apps/helpers/grgsm_channelize.py b/apps/helpers/grgsm_channelize.py
index 4098b7b..04b1633 100755
--- a/apps/helpers/grgsm_channelize.py
+++ b/apps/helpers/grgsm_channelize.py
@@ -37,11 +37,13 @@
 from gnuradio.filter import firdes
 from argparse import ArgumentParser, ArgumentTypeError, RawDescriptionHelpFormatter
 import grgsm.arfcn as arfcn
+from gnuradio.filter import pfb
+import math
 import os
 
 EXTRA_HELP = """
 Example usage:
-gsm_channelize.py -f my_wideband_capture.cfile -c 925.2e6 990 991 992 993 994 995 1019 1020 1021 1022 1023
+grgsm_channelize.py -f my_wideband_capture.cfile -c 925.2e6 990 991 992 993 994 995 1019 1020 1021 1022 1023
 
 The above example will channelize my_wideband_capture.cfile, in this case a cfile captured at
 925.2 MHz centered (ARFCN 975) and 20 Msps. As a result, 12 files will be generated for
@@ -61,31 +63,34 @@
     else:
         raise ArgumentTypeError("invalid GSM band: {0}. Possible choices are: {1}".format(value, choices))
 
-class gsm_channelize(gr.top_block):
-    def __init__(self, channels, decim, ch_width, ch_twidth, fc, band, samp_rate, path):
-        gr.top_block.__init__(self, "gsm_channelize")
+class grgsm_channelize(gr.top_block):
+    def __init__(self, channels, resamp_rate, fc, band, samp_rate, input_file, dest_dir, data_type="complex"):
+        gr.top_block.__init__(self, "grgsm_channelize")
 
         ##################################################
         # Parameters
         ##################################################
         self.channels = channels
-        self.decim = decim
-        self.ch_width = ch_width
-        self.ch_twidth = ch_twidth
+        self.resamp_rate = resamp_rate
         self.fc = fc
         self.band = band
         self.samp_rate = samp_rate
-        self.blocks_fir_filters = {}
+        self.blocks_resamplers = {}
+        self.blocks_rotators = {}
         self.blocks_file_sinks = {}
-
+        
         ##################################################
         # Blocks and connections
         ##################################################
-        self.blocks_file_source = blocks.file_source(gr.sizeof_gr_complex, path, False)
+        self.source = None
+        if data_type == "ishort":
+            self.blocks_file_source = blocks.file_source(gr.sizeof_short, input_file, False)
+            self.source = blocks.interleaved_short_to_complex(False, False)
+            self.connect((self.blocks_file_source, 0), (self.source, 0))
+        elif data_type == "complex":
+            self.source = blocks.file_source(gr.sizeof_gr_complex, input_file, False)
 
-        c0_arfcn = arfcn.downlink2arfcn(fc, band)
-        self.channels.insert(0, c0_arfcn)
-        print("Extracting channels %s, given that the center frequency is at ARFCN %d (%s)" % (str(channels), c0_arfcn, eng_notation.num_to_str(fc)))
+        print("Extracting channels %s, given that the center frequency is at %s" % (str(channels), eng_notation.num_to_str(fc)))
 
         for channel in channels:
             channel_freq = arfcn.arfcn2downlink(channel, band)
@@ -93,58 +98,68 @@
                 print("Warning: invalid ARFCN %d for band %s" % (channel, band))
                 continue
             freq_diff = channel_freq - fc
-            print("ARFCN %d is at C0 %+d KHz" % (channel, int(freq_diff / 1000.0)))
+            print("ARFCN %d is at fc %+d KHz" % (channel, int(freq_diff / 1000.0)))
 
-            self.blocks_fir_filters[channel] = filter.freq_xlating_fir_filter_ccc(decim, (firdes.low_pass(1, samp_rate, ch_width, ch_twidth)), freq_diff, samp_rate)
-            self.connect((self.blocks_file_source, 0), (self.blocks_fir_filters[channel], 0))
+            self.blocks_resamplers[channel] = pfb.arb_resampler_ccf( resamp_rate, taps=None, flt_size=32)
+            self.blocks_rotators[channel] = blocks.rotator_cc(-2*math.pi*(freq_diff)/samp_rate)
+            self.connect( (self.source, 0), (self.blocks_rotators[channel], 0) )
+            self.connect( (self.blocks_rotators[channel], 0), (self.blocks_resamplers[channel], 0) )
 
-            self.blocks_file_sinks[channel] = blocks.file_sink(gr.sizeof_gr_complex, "./gsm_channelizer/out_" + str(channel) + ".cfile", False)
+            self.blocks_file_sinks[channel] = blocks.file_sink(gr.sizeof_gr_complex, dest_dir+"/out_" + str(channel) + ".cfile", False)
             self.blocks_file_sinks[channel].set_unbuffered(False)
-            self.connect((self.blocks_fir_filters[channel], 0), (self.blocks_file_sinks[channel], 0))
+            self.connect((self.blocks_resamplers[channel], 0), (self.blocks_file_sinks[channel], 0))
 
 
 if __name__ == '__main__':
-    parser = ArgumentParser(formatter_class=RawDescriptionHelpFormatter, description='Split wideband a GSM capture into seperate files per ARFCN.', epilog=EXTRA_HELP)
+    parser = ArgumentParser(formatter_class=RawDescriptionHelpFormatter, description='Split wideband a GSM capture into seperate files per ARFCN.', add_help=True, epilog=EXTRA_HELP)
     parser.add_argument(dest="channel", type=int, nargs='+',
         help="List of ARFCNs")
-    parser.add_argument("-w", "--width", dest="width", type=eng_float, default=eng_notation.num_to_str(200000),
-        help="Channel lowpass width [default=%(default)s]")
-    parser.add_argument("-t", "--transition-width", dest="twidth", type=eng_float, default=eng_notation.num_to_str(50000),
-        help="Channel lowpass transition width [default=%(default)s]")
     parser.add_argument("-s", "--samp-rate", dest="samp_rate", type=eng_float, default=eng_notation.num_to_str(2e7),
         help="Sample rate of the wideband capture file [default=%(default)s]")
+    parser.add_argument("-f", "--fc", dest="fc", type=eng_float, default=eng_notation.num_to_str(935e6), required=True,
+        help="Carrier frequency in Hz [default=%(default)s]")
+    parser.add_argument("-b", "--band", dest="band", type=gsm_band, default='E-GSM',
+        help="GSM band [default=%(default)s]") #TODO: add automatic discovery based on fc
     parser.add_argument("-o", "--out-samp-rate", dest="out_samp_rate", type=eng_float, default=eng_notation.num_to_str(1e6),
         help="Sample rate of the output capture files [default=%(default)s]")
-    parser.add_argument("-b", "--band", dest="band", type=gsm_band, default='E-GSM',
-        help="GSM band [default=%(default)s]")
-    parser.add_argument("-f", "--cfile", dest="path", type=str, required=True,
+    parser.add_argument("-i", "--input_file", dest="input_file", type=str, required=True,
         help="Path to wideband GSM capture file")
-    parser.add_argument("-c", "--C0", dest="fc", type=eng_float, default=eng_notation.num_to_str(925.2e6), required=True,
-        help="C0 (BCCH) channel frequency in Hz [default=%(default)s]")
+    parser.add_argument("-t", "--data_type", dest="data_type", type=str, choices=["complex","ishort"], default="complex",
+        help="Type of the input file [default=%(default)s]")
+    parser.add_argument("-d", "--dest_dir", dest="dest_dir", type=str, 
+        help="Destination directory - if not given defaults to input file name without extension")
+        
     args = parser.parse_args()
+    
+    if not os.path.exists(args.input_file):
+        raise IOError(args.input_file + " does not exist")
 
-    if not os.path.exists("./gsm_channelizer"):
-        os.makedirs("./gsm_channelizer")
+    input_filename, _ = os.path.splitext(os.path.basename(args.input_file))
 
-    if not os.path.exists(args.path):
-        raise IOError(args.path + " does not exist")
+    if args.dest_dir is None:
+        args.dest_dir = input_filename
+    
+    if not os.path.exists("./"+args.dest_dir):
+        os.makedirs("./"+args.dest_dir)
+
 
     if args.samp_rate % args.out_samp_rate != 0:
         raise Exception("Input sample rate should be multiple of output sample rate in order to get integer decimation.")
 
-    decim = int(args.samp_rate / args.out_samp_rate)
+    resamp_rate = args.out_samp_rate / args.samp_rate
     print("Input sample rate: " + eng_notation.num_to_str(args.samp_rate))
     print("Output sample rate: " + eng_notation.num_to_str(args.out_samp_rate))
-    print("==> using decimation of " + str(decim))
+    print("==> using resample rate of " + str(resamp_rate))
 
-    tb = gsm_channelize(channels=args.channel,
-         decim=decim,
-         ch_width=args.width,
-         ch_twidth=args.twidth,
+    tb = grgsm_channelize(channels=args.channel,
+         resamp_rate=resamp_rate,
          fc=args.fc,
          band=args.band,
          samp_rate=args.samp_rate,
-         path=args.path)
+         input_file=args.input_file,
+         dest_dir=args.dest_dir,         
+         data_type=args.data_type
+         )
     tb.start()
     tb.wait()
     print("Done!")