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Un petit APRS Igate avec uniquement un Raspberry pi4, une clé RTL-SDR et direwolf!
Vous trouver ce qui faut pour installer une clé SDR puis GQRX afin de voir la fréquence de réception du 144.800MHz, qui chez moi se trouve décalé (144.794MHz).
Pour installer la clé SDR je me suis servi de :
https://github.com/wb2osz/direwolf/blob/master/doc/Raspberry-Pi-SDR-IGate.pdf
Pour GQRX les publication du REF (mais aussi pour installer la clé SDR):
https://publications.r-e-f.org/
Installation de direwolf 1.6 :
https://github.com/wb2osz/direwolf/blob/master/doc/Raspberry-Pi-APRS.pdf
Et je me suis arrêter au point 2.6, et il suffit d'aller modifier le fichier direwolf.conf dans /PI.
et de lancer la commande en ajustant sa fréquence de réception:
rtl_fm -f 144.80M - | direwolf -c direwolf.conf -r 24000 -D 1 -
Je trouve que ça marche mieux en passant en Narrow FM:
rtl_fm -f 144.80M -M nfm - | direwolf -c direwolf.conf -r 24000 -D 1 -
Je n'ai pas fait la commande pour avoir la dernière version non stable du point 2.3 (git checkout dev)
Pour affiner, j'ai trouvé les options pour les commandes RTL-FM:
rtl_fm [-f freq] [-options] [filename]
-OPTIONS
-f frequency_to_tune_to [Hz]
use multiple -f for scanning, (requires squelch)
ranges supported, -f 118M:137M:25k
-M modulation (default: fm)]"
fm, wbfm, raw, am, usb, lsb
wbfm
-M fm -s 170k -o 4 -A fast -r 32k -l 0 -E deemp
raw mode outputs 2x16 bit IQ pairs
-s sample_rate (default: 24k)
-d device_index (default: 0)
-g tuner_gain (default: automatic)
-l squelch_level (default: 0/off)
-o oversampling (default: 1, 4 recommended)
for fm squelch is inverted
-p ppm_error (default: 0)
[-E enable_option (default: none)]
use multiple -E to enable multiple options
edge: enable lower edge tuning
dc: enable dc blocking filter
deemp: enable de-emphasis filter
direct: enable direct sampling
offset: enable offset tuning
Filename ('-' means stdout)
omitting the filename also uses stdout
Experimental options
-r resample_rate (default: none / same as -s)]
-t squelch_delay (default: 10)]
values will mute/scan, -values will exit
[-F fir_size (default: off)]
enables low-leakage downsample filter
size can be 0 or 9. 0 has bad roll off
-A std/fast/lut choose atan math (default: std)
filename
(a '-' dumps samples to stdout)
(omitting the filename also uses stdout)
Et aussi les commandes ou Options pour Direwolf:
Options
-c file : Read configuration file from specified location rather than the default locations.
-l logdir : Generate daily log files in specified directory. Use "." for current directory.
-L logfile : Generate single log file with fixed name.
-r n : Audio sample rate per second for first channel. Default 44100.
-n n : Number of audio channels for first device. 1 or 2. Default 1.
-b n : Audio sample size for first channel. 8 or 16. Default 16.
-B n :Data rate in bits/sec for first channel. Standard values are 300, 1200, 2400, 4800, 9600.
300 bps defaults to AFSK tones of 1600 & 1800.
1200 bps uses AFSK tones of 1200 & 2200.
2400 bps uses QPSK based on V.26 standard.
4800 bps uses 8PSK based on V.27 standard.
9600 bps and up uses K9NG/G3RUH standard.
AIS for ship Automatic Identification System.
EAS for Emergency Alert System (EAS) Specific Area Message Encoding (SAME).
-g : Force G3RUH modem regardless of data rate.
-j : 2400 bps QPSK compatible with Dire Wolf <= 1.5.
-J : 2400 bps QPSK compatible with MFJ-2400.
-D n : Divide audio sample by n for first channel.
-X n : 1 to enable FX.25 transmit. 16, 32, 64 for specific number of check bytes.
-I n : Enable IL2P transmit. n=1 is recommended. 0 uses weaker FEC.
-i n : Enable IL2P transmit, inverted polarity. n=1 is recommended. 0 uses weaker FEC.
-d x : Debug options. Specify one or more of the following in place of x.
a = AGWPE network protocol client.
k = KISS serial port client.
n = Network KISS client.
u = Display non-ASCII text in hexadecimal.
p = Packet dump in hexadecimal.
g = GPS interface.
W = Waypoints for position or object reports.
t = Tracker beacon.
o = Output controls such as PTT and DCD.
i = IGate
h = Hamlib verbose level. Repeat for more.
m = Monitor heard station list.
f = Packet filtering.
x = FX.25 increase verbose level.
d = APRStt (DTMF to APRS object conversion).
-q x : Quiet (suppress output). Specify one or more of the following in place of x.
h = Heard line with the audio level.
d = Decoding of APRS packets.
x = Silence FX.25 information.
-t n : Text colors. 0=disabled. 1=default. 2,3,4,... alternatives. Use 9 to test compatibility with your terminal.
-p : Enable pseudo terminal for KISS protocol.
-x : Send Xmit level calibration tones.
a = Alternating mark/space tones.
m = steady Mark tone (e.g. 1200 Hz)
s = steady Space tone (e.g. 2200 Hz)
p = selence (set Ptt only).
Optionally add a number to specify radio channel.
-u : Print UTF-8 test string and exit.
-S : Print Symbol tables and exit.
-a n : Report audio device statistics each n seconds.
-T fmt : Time stamp format for sent and received frames.
-e ber : Receive Bit Error Rate (BER), e.g. 1e-5
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