aprx-stat(8)                                                      aprx-stat(8)



NAME
       aprx-stat - statistics utility for aprx(8)

SYNOPSIS
       aprx-stat [-t] [-f /tmp/aprx-erlang.dat] {-S|-x|-X}

DESCRIPTION
       aprx-stat is a statistics utility for aprx(8) program.


OPTIONS
       The aprx-stat has following runtime options:

       -t     Use  UNIX  time_t for timestamps, instead of human readable text
              format.

       -f /tmp/aprx-erlang.dat
              Turn on verbose debugging, outputs data to STDOUT.

       -S     SNMP data mode, current counter and gauge values.

       -x     Lattest of extended historical gauge  values.   This  gives  for
              each input interface

              • SNMP data

              • last 90 of 1 minute values,

              • 10 of 10 minute values,

              • 3 of 60 minute values.

       -X     Full  extended historical gauge values.  This gives all the con-
              tents of historical value data ring-buffers.

              • SNMP data

              • 1 minute resolution: 24 hours

              • 10 minute resolution: 7 days

              • 60 minute resolution: 3 months


SNMP DATA OUTPUT
       For each interface feeding AX.25 packets and/or  KISS  frames  to  this
       program, there are following kind of

       SNMP  /dev/ttyUSB1   798282 11088   0  0     3
       SNMP  ax0   798282 11088   0  0     7
       SNMP  ax1   798282 11088   0  0     94

       where columns are:

       • "SNMP" - keyword

       • Interface (AX.25 IF name, or serial port device name)

       • Received byte counter

       • Received KISS frame (packet) counter

       • Transmitted byte counter (will stay zero)

       • Transmitted KISS frame counter  (will stay zero)

       • Age in seconds of last update of this statistics.


EXTENDED DATA OUTPUT
       Extended data output gives formatted historical periodic accumulates of
       interface traffic counters, and Erlang value estimates based on that.



       SNMP  /dev/ttyUSB1   816675 11332   0  0     15

       1min data
       2007-12-24 14:10  /dev/ttyUSB1  1m    374    6      0    0   0.047  0.000
       2007-12-24 14:09  /dev/ttyUSB1  1m    377    5      0    0   0.047  0.000
       2007-12-24 14:08  /dev/ttyUSB1  1m    347    5      0    0   0.043  0.000
       2007-12-24 14:07  /dev/ttyUSB1  1m    140    2      0    0   0.018  0.000
       •••

       10min data
       2007-12-24 14:10  /dev/ttyUSB1 10m   3829   55      0    0   0.048  0.000
       2007-12-24 14:00  /dev/ttyUSB1 10m   2182   28      0    0   0.027  0.000
       2007-12-24 13:50  /dev/ttyUSB1 10m   3205   44      0    0   0.040  0.000
       2007-12-24 13:40  /dev/ttyUSB1 10m   3811   50      0    0   0.048  0.000
       •••

       60min data
       2007-12-24 14:00  /dev/ttyUSB1 60m  22510  295      0    0   0.047  0.000
       2007-12-24 13:00  /dev/ttyUSB1 60m  24886  347      0    0   0.052  0.000
       •••

       The output repeats for all interfaces.

       The SNMP dataset is given in the beginning, and described above.   Then
       each extended output line has following fields:

       • Timestamp  is  two fields, date and time (in minute resolution) is in
         UTC.

       • Alternate timestamp format is UNIX time_t  as  an  integer,  counting
         seconds from epoch, and as single field.

       • Interface name is same as in SNMP case.

       • Data  qualifier  tells what integration period the data is valid for:
         1m, 10m, 60m.

       • Counter of received bytes on interface (including KISS flags etc.)

       • Counter of received frames.

       • Counter of transmitted bytes on interface

       • Counter of transmitted frames.

       • Reception Erlang value estimate.

       • Transmission Erlang value estimate.


TODO
BUGS
SEE ALSO
       aprx(8)


CONFIGURATION FILE
       There is no configuration file.


NOTES: ERLANG
       The Erlang is telecom measurement of channel  occupancy,  and  in  this
       application  sense  it does tell how much traffic there is on the radio
       channel.

       Most radio transmitters are not aware of all transmitters  on  channel,
       and  thus  there  can happen a collision causing loss of both messages.
       The higher the channel activity, the more  likely  that  collision  is.
       For further details, refer to statistical mathematics books, or perhaps
       on Wikipedia.

       In order to measure channel activity, the aprx program suite has  these
       built-in statistics counter and summary estimators.

       The  Erlag value that the estimators present are likely somewhat under-
       estimating the true channel  occupancy  simply  because  it  calculates
       estimate  of channel bit transmit rate, and thus a per-minute character
       capacity.  It does not know true frequency of  bit-stuffing  events  of
       the  HDLC  framing, nor each transmitter pre- and port frame PTT times.
       The transmitters need to stabilize their transmit oscillators  in  many
       cases,  which may take up to around 500 ms!  The counters are not aware
       of this preamble-, nor postamble-times.

       The HDLC bit stuffing ratio is guessed to be 8.2 bits for each  8  bits
       of payload.



NOTES: SUID ROOT
       This program needs probably to be run as suid-root !  It is fairly safe
       to do so, as this checks that the -f parameter file is of correct time,
       and will not try to create create it if it does not exist.


AUTHOR
       This little piece was written by Matti Aarnio, OH2MQK during a dark and
       rainy fall and winter of 2007-2008 after a number of discussions  grum-
       bling  about  current breed of available software for APRS iGate use in
       Linux (or of any UNIX) platforms.

       Principal contributors and test users include: Pentti Gronlund,  OH3BK,
       Reijo Hakala, OH1GWK.



                           2007 December 25 - v0.12               aprx-stat(8)