Added example that can be run without GUI or example trace

.gitignore

@@ -8,3 +8,4 @@ dev/
 apps/test-suites
 *.sigmf-data
 *.sigmf-meta
+apps/test-trace.*

apps/lora_receive_file_nogui.py

@@ -0,0 +1,103 @@
+#!/usr/bin/env python2
+# Gets a USRP capture trace from my research page and decodes it using gr-lora.
+# Author: Pieter Robyns
+
+from gnuradio import blocks
+from gnuradio import eng_notation
+from gnuradio import gr
+from gnuradio.eng_option import eng_option
+from gnuradio.filter import firdes
+from optparse import OptionParser
+from lora.loraconfig import LoRaConfig
+from time import sleep
+import lora
+import argparse
+import os
+import requests
+import json
+
+class lora_receive_file_nogui(gr.top_block):
+    def __init__(self, sample_file, sample_rate, capture_freq, lc):
+        gr.top_block.__init__(self, "Lora Receive File, No GUI")
+        ##################################################
+        # Variables
+        ##################################################
+        self.internal_sample_rate = 1e6
+
+        ##################################################
+        # Blocks
+        ##################################################
+        self.message_socket_sink = lora.message_socket_sink('127.0.0.1', 40868, False, False)
+        self.lora_receiver = lora.lora_receiver(sample_rate, capture_freq, ([lc.freq]), lc.sf, self.internal_sample_rate, lc.implicit, lc.cr_num, lc.crc)
+        self.blocks_throttle = blocks.throttle(gr.sizeof_gr_complex, sample_rate, True)
+        self.blocks_file_source = blocks.file_source(gr.sizeof_gr_complex, sample_file, False)
+
+        ##################################################
+        # Connections
+        ##################################################
+        self.msg_connect((self.lora_receiver, 'frames'), (self.message_socket_sink, 'in'))
+        self.connect((self.blocks_file_source, 0), (self.blocks_throttle, 0))
+        self.connect((self.blocks_throttle, 0), (self.lora_receiver, 0))
+
+def download_file(source, destination):
+    print("[+] Downloading %s -> %s" % (source, destination)),
+    try:
+        response = requests.get(source, stream=True)
+
+        with open(destination, 'wb') as f:
+            for chunk in response.iter_content(1000*1000):
+                f.write(chunk)
+                print("."),
+            print(".")
+    except Exception as e:
+        print("[-] " + str(e))
+        exit(1)
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description="Gets a USRP capture trace from my research page and decodes it using gr-lora.")
+    parser.add_argument('--file', type=str, default="example-trace", help='File name of the example trace.')
+    parser.add_argument('--skip-download', default=False, action='store_true', help='Skip downloading the example trace.')
+    args = parser.parse_args()
+
+    data_file_path = os.path.join('./', args.file + '.sigmf-data')
+    meta_file_path = os.path.join('./', args.file + '.sigmf-meta')
+
+    if not args.skip_download and \
+       not (os.path.exists(data_file_path) and os.path.exists(meta_file_path)) and \
+       raw_input("[?] Download test LoRa signal to decode? [y/N] ").lower() == "y":
+        download_file("https://research.edm.uhasselt.be/probyns/lora/usrp-868.1-sf7-cr4-bw125-crc-0.sigmf-data", data_file_path)
+        download_file("https://research.edm.uhasselt.be/probyns/lora/usrp-868.1-sf7-cr4-bw125-crc-0.sigmf-meta", meta_file_path)
+        sleep(3)
+    else:
+        print("[+] Skipping download.")
+
+    if os.path.exists(data_file_path) and os.path.exists(meta_file_path):
+        metadata = json.load(open(meta_file_path, "r"))
+        meta_global = metadata["global"]
+        meta_capture = metadata["captures"][0]
+
+        # Parse metadata. Not using SigMF library because of extra dependency
+        sample_rate = meta_global["core:sample_rate"]
+        capture_freq = meta_capture["core:frequency"]
+        transmit_freq = meta_capture["lora:frequency"]
+        sf = meta_capture["lora:sf"]
+        cr = meta_capture["lora:cr"]
+        bw = meta_capture["lora:bw"]
+        prlen = meta_capture["lora:prlen"]
+        crc = meta_capture["lora:crc"]
+        implicit = meta_capture["lora:implicit"]
+        lora_config = LoRaConfig(transmit_freq, sf, cr, bw, prlen, crc, implicit)
+        print("[+] Configuration: %s" % lora_config.string_repr())
+
+        # Decode the data!
+        payload = meta_capture["test:expected"]
+        times = meta_capture["test:times"]
+        print("[+] Decoding. You should see a header, followed by '%s'%s %d times." % (payload, " and a CRC" if crc else "", times))
+        tb = lora_receive_file_nogui(data_file_path, sample_rate, capture_freq, lora_config)
+        tb.start()
+        tb.wait()
+        print("[+] Done")
+        exit(0)
+    else:
+        print("[-] Example trace or metadata missing! Exiting.")
+        exit(1)

python/loraconfig.py

@@ -3,14 +3,14 @@ class LoRaConfig():
         self.freq = freq
         self.sf = sf
         self.cr = cr
+        self.cr_num = int(self.cr.rpartition('/')[2])-4
         self.bw = bw
         self.prlen = prlen
         self.crc = crc
         self.implicit = implicit
 
     def file_repr(self):
-        cr_num = int(self.cr.rpartition('/')[2])-4
-        format_string = "{:n}-sf{:n}-cr{:n}-bw{:n}".format(self.freq/1000000.0, self.sf, cr_num, self.bw/1000.0)
+        format_string = "{:n}-sf{:n}-cr{:n}-bw{:n}".format(self.freq/1000000.0, self.sf, self.cr_num, self.bw/1000.0)
         if self.crc:
             format_string += "-crc"
         if self.implicit: