Add Lucky-7 image receiver

The implementation is based on
https://github.com/Xerbo/Lucky7-Decoder

This closes csete#192

Author: daniestevez

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support for SPOC
 - PDU add metadata block
 - Support for AISTECHSAT-2 custom protocol
+- Lucky-7 image receiver
 
 ### Changed
 - Replaced boost::bind() by C++ lambdas

docs/source/command_line.rst

@@ -573,8 +573,8 @@ displayed in real time as they are being received, using `feh`_.
 
 Currently the satellites that have decoders supporting file reception are ATL-1
 and SMOG-P (they transmit RF spectrum data), and the satellites that have
-decoders supporting image reception are 1KUNS-PF, BY70-1, D-SAT, LilacSat-1 and
-Światowid.
+decoders supporting image reception are 1KUNS-PF, BY70-1, D-SAT, LilacSat-1,
+Lucky-7 and Światowid.
 
 For satellites supporting file reception, the ``--file_output_path`` parameter
 can be used to set the directory that is used to store received files. The

python/filereceiver/CMakeLists.txt

@@ -37,6 +37,7 @@ GR_PYTHON_INSTALL(
     k2sat.py
     filereceiver.py
     imagereceiver.py
+    lucky7.py
     sat_1kuns_pf.py
     smogp.py
     swiatowid.py

python/filereceiver/__init__.py

@@ -18,6 +18,7 @@
 from .by70_1 import by70_1
 from .dsat import dsat
 from .k2sat import k2sat
+from .lucky7 import lucky7
 from .sat_1kuns_pf import sat_1kuns_pf
 from .smogp import smogp
 from .swiatowid import swiatowid

python/filereceiver/lucky7.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# Copyright 2020 Daniel Estevez <daniel@destevez.net>
+#
+# This file is part of gr-satellites
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+# Based on the decoder by Xerbo
+# https://github.com/Xerbo/Lucky7-Decoder
+
+import struct
+
+from .imagereceiver import ImageReceiver
+
+class ImageReceiverLucky7(ImageReceiver):
+    def chunk_sequence(self, chunk):
+        return struct.unpack('>H', chunk[3:5])[0]
+
+    def chunk_size(self):
+        return 28
+    
+    def chunk_data(self, chunk):
+        return chunk[7:]
+
+    def file_size(self, chunk):
+        return self.chunk_size() * struct.unpack('>H', chunk[5:7])[0]
+
+    def parse_chunk(self, chunk):
+        address = struct.unpack('>H', chunk[1:3])[0]
+        if address < 0xC000 \
+          or address >= 0xC000 + self.file_size(chunk)/self.chunk_size():
+            return None
+        return chunk    
+
+lucky7 = ImageReceiverLucky7

python/satyaml/Lucky-7.yml

@@ -3,6 +3,8 @@ norad: 44406
 data:
   &tlm Telemetry:
     unknown
+  &image Image:
+    image: lucky7
 transmitters:
   4k8 FSK downlink:
     frequency: 437.525e+6
@@ -11,3 +13,4 @@ transmitters:
     framing: Lucky-7
     data:
     - *tlm
+    - *image