[aprssig] aprx bug continues!

Heikki Hannikainen hessu at hes.iki.fi
Sun Mar 9 17:47:29 CDT 2014


On Sun, 9 Mar 2014, Steve Dimse wrote:

> Today there are a bunch more of big spikes in APRS-IS volume, after a 
> bit of detective work each spike is being caused by a single station.
>
> mysql> select count(*) from raw where `call` = "YB6HJE-3" and time_rx > 20140309000000;
> +----------+
> | count(*) |
> +----------+
> |   174914 |
> +----------+

The spikes are quite massive, over 70000 packets per hour:

http://aprs.fi/info/graphs/a/YB6HJE-3

> Matti tells me this is from a feature in his program that sends out data 
> that was missed while his program was sleeping, though today's spikes 
> make me question that - they seem too close together to have generated 
> that much data.

The problem was in the timer code handling - if the clock stops and then 
jumps forward a bit due to a sleep, there will be a small spike.

If the clocks goes back to year 1996 (or whatever year your computer's 
BIOS was made) due to a dead clock backup battery, and a little power 
failure, aprx starts, and then NTP brings it forward to today, there will 
apparently be a large spike.

I suppose this could also hit gateways running on systems without a 
battery-backed real-time clock, like a Raspberry Pi or an OpenWRT-based 
router.

> I've tried multiple times to contact YB6HJE through the QRZ email. If 
> anyone has a means to contact him please try. And don't use aprsx on any 
> computer that has a sleep mode!

The name of the program is actually 'aprx'.

It'd probably be best to ugprade to the most recent version, aprx 2.08 
(svn558/559), which already contains the fixes for the bug.

I just sent twitter & facebook messages to YB6HJE. At least the FB account 
seems active, he's updated it just yesterday.

   - Hessu



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