Utah Traffic Net Recordings

Efforts to automate the W7YV shack operations are continuing. The latest addition to the shack is the automatic recording of several traffics nets that are routinely visited here at W7YV.

These recordings my be of general interest but, more importantly, may be of use to those taking traffic on these nets as a means to verify what they thought they copied.

Using a computer running Ubuntu Linux, a "cron job" has been setup to start an "arecord" session at the times of various traffic nets.

This is an experiment and might go away. If it does, well, fine then. Until that happens, check out this link: http://63.226.66.243:8080/nets . At present, files are kept for one week.

This link is shown at the top of the HF Nets section on the right side of this blog.

Implementation

The setup here at W7YV includes a PC running Linux Ubuntu 11.10. The PC is interfaced to an ICOM IC-756PRO.

At present, the process is mostly manual in that the operator has to be present to setup equipment. The expectation is that much of this will be automated in the coming months. If the operator is present to monitor or call the net, the recordings will probably happen. If not, probably not.

The Linux program "arecord" is used to capture the audio and the Linux program "lame" is used to convert the captured WAV format to MP3.

A bash script is launched by a "cron job" at the beginning of the nets and runs for a fixed time interval. These time intervals are still being worked out. Listings of the various scripts follow:

recordAudioFile.sh

#!/usr/bin/env bash

# SCRIPT: recordAudioFile.sh
# PURPOSE: Records an audio file using arecord
# command format:
# recordAudioFile.sh duration_seconds filename_prefix"
#
# REVISIONS:
# 12/17/2012 JRH Initial creation

arecord -f cd -d $1 -t wav | lame --preset 56 -mm - $2.mp3

Problems:

1. The mixer settings are not stable. The audio settings are destroyed by other processes running prior to the cron job. A means to preset these mixer settings is needed.
2. Recording duration need adjustment. It seems prudent to "over record" and trim the files later. The duration of any given net cannot be predicted.

crontab -l

In Linux, a "cron job" is a scheduled job that runs based on instructions in "crontab." Here is a "snapshot" of the crontab used at W7YV: 

# m h  dom mon dow   command

#########################################################

# Twelfth Region Net SSB

# Announce

#########################################################

55 06 * * * ~/bin/cron_messages.sh "TWN 3923.5 KHz 0700 LT"

00 07 * * * ~/bin/recordAudioFile.sh 300 Nets/TWN0

#########################################################

# Wyoming Jackalope Net

# Announce and begin recording

#########################################################

15 12 * * * ~/bin/recordAudioFile.sh 900 Nets/WJN

#########################################################

# Wyoming Cowboy Net

# Announce and record

#########################################################

45 17 * * * ~/bin/recordAudioFile.sh 1200 Nets/WCN

#########################################################

# Utah Code Net

# Announce and record

#########################################################

30 19 * * * ~/bin/recordAudioFile.sh 900 Nets/UCN

#########################################################

# Mountain States Net

# Announce and record

#########################################################

00 20 * * * ~/bin/recordAudioFile.sh 1200 Nets/MSN

#########################################################

# Twelfth Region Net

# Announce and record

#########################################################

30 20 * * * ~/recordAudioFile.sh 1200 Nets/TWN1

#########################################################

# Twelfth Region Net

# Announce and record

#########################################################

00 22 * * * ~/bin/recordAudioFile.sh 1500 Nets/TWN2

Enjoy!