gen_packets - Generate audio file for AX.25 frames.

NAME SYNOPSIS DESCRIPTION OPTIONS EXAMPLES SEE ALSO

NAME

gen_packets − Generate audio file for AX.25 frames.

SYNOPSIS

gen_packets −o wav-file-out [ options ] [ text-file | − ]

wav-file-out is the result. The −o option is required.

text-file may contain AX.25 packets in the standard monitoring format. Use "-" to read from stdin. If not specified, a default builtin message will be used.

DESCRIPTION

gen_packets is a test application which converts text to AX.25 audio for testing packet decoders.

It is very flexible allowing a wide range of audio sample rates, data speeds, and AFSK tones. It will even generate the scrambled signals commonly used for 9600 baud operation.

OPTIONS

	-a n		Signal amplitude in range of 0-200%. Default 50. Note that 100% is corresponds to signal peaks of +/- 16383 so we have plenty of headroom to avoid saturation.
	-b n		Bits / second for data. Default is 1200.
	-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.
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.
	-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.
	-m n		Mark frequency. Default is 1200.
	-s n		Space frequency. Default is 2200.
	-r n		Audio sample Rate. Default is 44100.
	-n n		Generate specified number of frames with increasing noise. (For built-in message only.)

-o file

Send output to .wav file.

	-8		8 bit audio rather than 16.
	-2		2 channels of audio rather than 1.

-vmax[,incr]

Variable speed with specified maximum error and optional increment.

EXAMPLES

gen_packets −o x.wav

With all defaults, a built-in test message is generated with standard Bell 202 tones used for packet radio on ordinary VHF FM transceivers.

gen_packets −o x.wav −g −b 9600
gen_packets −o x.wav −B 9600

Both of these are equivalent. "-B 9600" automatically selects scrambled baseband rather than AFSK.

gen_packets −o x.wav −m 1600 −s 1800 −b 300
gen_packets −o x.wav −B 300

Both of these generate 200 Hz shift, 300 baud, suitable for HF SSB transceiver.

echo −n ’WB2OSZ>WORLD:Hello, world!’ | gen_packets −a 25 −o x.wav −
atest x.wav

Read message from stdin and put quarter volume sound into the file x.wav. Decode the sound file.