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freq offset handling #81

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first attempt just with pings. Station A sends a ping to Station B. Station B is detecting RX offset, adds it to the ping acknowledge frame and sends it back to Station A. Station A will then adjust the frequency
This commit is contained in:
DJ2LS 2021-10-13 19:39:46 +02:00
parent 82f307cf1f
commit 655d333af2
2 changed files with 49 additions and 8 deletions
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14
tnc/data_handler.py
View file

@ -504,8 +504,13 @@ def arq_transmit(data_out, mode, n_frames_per_burst):
elif BURST_ACK_RECEIVED and static.ARQ_STATE == 'DATA':
# -----------IF ACK RECEIVED, INCREMENT ITERATOR FOR MAIN LOOP TO PROCEED WITH NEXT FRAMES/BURST
TX_N_SENT_FRAMES = TX_N_SENT_FRAMES + TX_N_FRAMES_PER_BURST
# SET TX ATTEMPTS BACK TO 0
TX_N_RETRIES_PER_BURST = 0
calculate_transfer_rate_tx(TX_N_SENT_FRAMES, TX_PAYLOAD_PER_ARQ_FRAME, TX_START_OF_TRANSMISSION, TX_BUFFER_SIZE)
logging.info("ARQ | RX | ACK [" + str(static.ARQ_BITS_PER_SECOND) + " bit/s | " + str(static.ARQ_BYTES_PER_MINUTE) + " B/min]")
# lets wait a little bit before we are processing the next frame
helpers.wait(0.3)
@ -771,7 +776,7 @@ def transmit_ping(callsign):
time.sleep(0.01)
def received_ping(data_in):
def received_ping(data_in, frequency_offset):
static.DXCALLSIGN_CRC8 = bytes(data_in[2:3]).rstrip(b'\x00')
static.DXCALLSIGN = bytes(data_in[3:9]).rstrip(b'\x00')
@ -785,7 +790,12 @@ def received_ping(data_in):
ping_frame[1:2] = static.DXCALLSIGN_CRC8
ping_frame[2:3] = static.MYCALLSIGN_CRC8
ping_frame[3:9] = static.MYGRID
ping_frame[9:11] = frequency_offset.to_bytes(2, byteorder='big', signed=True)
#print(len(frequency_offset.to_bytes(2, byteorder='big', signed=True)))
#print(ping_frame)
#print(ping_frame[9:11])
#print(int.from_bytes(bytes(ping_frame[9:11]), "big", signed=True))
# wait while sending....
while not modem.transmit_signalling(ping_frame, 1):
time.sleep(0.01)

43
tnc/modem.py
View file

@ -271,6 +271,7 @@ class RF():
converted_audio = audioop.ratecv(self.streambuffer, 2, 1, self.MODEM_SAMPLE_RATE, self.AUDIO_SAMPLE_RATE_TX, None)
self.streambuffer = bytes(converted_audio[0])
# append frame again with as much as in count defined
for i in range(1, count):
self.streambuffer += bytes(converted_audio[0])
@ -398,6 +399,12 @@ class RF():
datac0_bytes_per_frame = int(self.c_lib.freedv_get_bits_per_modem_frame(datac0_freedv)/8)
datac0_n_max_modem_samples = self.c_lib.freedv_get_n_max_modem_samples(datac0_freedv)
self.c_lib.freedv_set_clip(datac0_freedv, 1);
self.c_lib.freedv_set_tx_bpf(datac0_freedv, 1);
#freedv_set_tx_amp(datac0_freedv, amp);
# bytes_per_frame
datac0_bytes_out = (ctypes.c_ubyte * datac0_bytes_per_frame)
datac0_bytes_out = datac0_bytes_out() # get pointer from bytes_out
@ -448,7 +455,7 @@ class RF():
'''
fft_buffer = bytes()
while True:
#time.sleep(0.0005)
'''
# refresh vars, so the correct parameters of the used mode are set
if mode == static.ARQ_DATA_CHANNEL_MODE:
@ -463,6 +470,7 @@ class RF():
data_in = data_in[0] # .rstrip(b'\x00')
#self.fft_data = data_in
# we need to set nin * 2 beause of byte size in array handling
datac0_nin = self.c_lib.freedv_nin(datac0_freedv) * 2
datac1_nin = self.c_lib.freedv_nin(datac1_freedv) * 2
@ -488,12 +496,14 @@ class RF():
self.c_lib.freedv_rawdatarx.argtype = [ctypes.POINTER(ctypes.c_ubyte), datac0_bytes_out, datac0_audio]
nbytes = self.c_lib.freedv_rawdatarx(datac0_freedv, datac0_bytes_out, datac0_audio) # demodulate audio
sync = self.c_lib.freedv_get_rx_status(datac0_freedv)
self.get_scatter(datac0_freedv)
if sync != 0 and nbytes != 0:
# calculate snr and scatter
self.get_scatter(datac0_freedv)
self.calculate_snr(datac0_freedv)
datac0_task = threading.Thread(target=self.process_data, args=[datac0_bytes_out, datac0_freedv, datac0_bytes_per_frame])
#datac0_task.start()
self.process_data(datac0_bytes_out, datac0_freedv, datac0_bytes_per_frame)
@ -592,11 +602,22 @@ class RF():
# PING FRAME
elif frametype == 210:
logging.debug("PING RECEIVED....")
data_handler.received_ping(bytes_out[:-2])
frequency_offset = self.get_frequency_offset(freedv)
print("Freq-Offset: " + str(frequency_offset))
data_handler.received_ping(bytes_out[:-2], frequency_offset)
# PING ACK
elif frametype == 211:
logging.debug("PING ACK RECEIVED....")
# early detection of frequency offset
frequency_offset = int.from_bytes(bytes(bytes_out[9:11]), "big", signed=True) * (-1)
print("Freq-Offset: " + str(frequency_offset))
current_frequency = self.my_rig.get_freq()
corrected_frequency = current_frequency + frequency_offset
self.my_rig.set_vfo(Hamlib.RIG_VFO_A)
self.my_rig.set_freq(Hamlib.RIG_VFO_A, corrected_frequency)
data_handler.received_ping_ack(bytes_out[:-2])
# ARQ FILE TRANSFER RECEIVED!
@ -630,6 +651,14 @@ class RF():
pass
# print(bytes_out[:-2])
def get_frequency_offset(self, freedv):
modemStats = MODEMSTATS()
self.c_lib.freedv_get_modem_extended_stats.restype = None
self.c_lib.freedv_get_modem_extended_stats(freedv, ctypes.byref(modemStats))
offset = round(modemStats.foff) * (-1)
return offset
def get_scatter(self, freedv):
modemStats = MODEMSTATS()
self.c_lib.freedv_get_modem_extended_stats.restype = None
@ -715,12 +744,14 @@ class RF():
dfft = np.around(dfft, 1)
dfftlist = dfft.tolist()
# send fft only if receiving
if static.CHANNEL_STATE == 'RECEIVING_SIGNALLING' or static.CHANNEL_STATE == 'RECEIVING_DATA':
#static.FFT = dfftlist[20:100]
#static.FFT = dfftlist[10:200]
static.FFT = dfftlist
except:
print("setting fft = 0")
# else 0