[aprssig] IGate issue

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Tue Mar 18 04:50:20 CDT 2014


And interestingly enough, here's a response from Hessu on his aprs.fi 
Google group just this morning dealing with the same question:

> On Wed, 12 Mar 2014, Asbjørn Hauge wrote:
>
>> I've noticed a strange behaviour about heard positions-map lately. If 
>> I look at station info and select "show on map" (heard directly), I 
>> miss a lot of positions
>> where I've been credited for the qAR according to raw data.
>
> qAR indicates the igate (station which passed the packet to the 
> APRS-IS from RF), not the station which heard the packet first / 
> directly. Try the 'gated' map (Position packets sent to APRS-IS => 
> Show on map) instead to see the full service area of the igate:
>
> http://aprs.fi/#!v=gated&call=a%2FLA1HSA-1&timerange=3600&tail=3600
>
>> http://aprs.fi/#!mt=roadmap&z=11&v=heard&ym=201403&call=a%2FLA1HSA-1&timerange=3600&tail=3600 
>>
>> This map does not show LD2BI even though I'm igating it on a regular 
>> basis. This isn't critical for local use, although it's nice to see 
>> coverage.
>
> LD2BI arrives to your igate with a WIDE2-1 path, which gives aprs.fi a 
> strong hint that this packet has been digipeated by some digipeater 
> first, and it's probably not "heard first" by your igate. From over 
> here, behind the APRS-IS, it's really hard to tell whether LD2BI 
> transmitted with a WIDE2-1 path originally, or if the packet went 
> through a digipeater and WIDE2-2 got adjusted to WIDE2-1.
>
>> A more interesting situation was the balloon M0XER-8 
>> (http://aprs.fi/#!mt=roadmap&z=11&call=a%2FM0XER-8&timerange=604800&tail=604800). 
>> I did not get any hits for
>> this on the "heard map" for February, which is sad since I really 
>> wanted to see the path when it was high up in the air.
>
> Same here, WIDE2-1 path.
>
> This is a frequently asked question, please search the discussion 
> group archive for "heard", there's a lot of questions and answers on 
> the topic already.
>
>   - Hessu 


On 3/18/2014 5:37 AM, Lynn W. Deffenbaugh (Mr) wrote:
> From 
> http://wiki.ham.fi/Aprs.fi_Info_pages#Stations_heard_by_X.2C_and_stations_which_heard_Y
>
>>
>>         Stations heard by X, and stations which heard Y
>>
>> aprs.fi collects monthly summaries of digipeater and igate 
>> statistics. The info page shows both a table of digipeaters and 
>> igates which heard the given station, and (if the station is a 
>> digipeater or igate) which other stations where heard by that 
>> station. The most recently updated entries are shown using a larger 
>> font.
>>
>> These statistics are usually somewhat correct, but there are several 
>> caveats, and as you've probably heard -- there are lies, damn lies, 
>> and statistics.
>>
>>   * The APRS-IS network that feeds the APRS packets from the igates
>>     to aprs.fi does duplicate suppression. Only the first gated copy
>>     of a packet traverses the entire network. All other duplicate
>>     copies seen within 30 seconds after the first packet are dropped
>>     by APRS-IS. A packet which is heard by multiple igates normally
>>     gets credited only for a single igate.
>>   * A lot of digipeaters do not add their own callsign in the
>>     packet's path when retransmitting a packet. aprs.fi cannot
>>     possibly know about those.
>>   * A lot of digipeaters do callsign substitution instead of
>>     insertion, replacing original path components. A packet with a
>>     path of OH7RDÖ,WIDE2-1 could have been a WIDE1-1,WIDE2-1 packet
>>     in the first place, and gone through OH7RDÖ and another unknown
>>     digipeater.
>>   * The aprs.fi "first heard" algorithm tries to go on the safe side:
>>     if it's not sure, it doesn't count as directly heard. But even
>>     then, some incorrect overly long paths are shown.
>>   * Stations transmitting invalid or fake coordinates will skew these
>>     statistics. If the transmitting station claims to be 1000 km away
>>     (due to a bad GPS fix), my best guess can only be that the
>>     station actually is that far away.
>>   * Items and objects are not shown here, since they are usually far
>>     away from the transmitter which transmitted the packets.
>>
>
> Packets have to meet a lot of criteria to be called "Heard by" at 
> aprs.fi.  Most likely cause is that all of your stations are using the 
> recommended path of "WIDE1-1,WIDE2-1" which aprs.fi doesn't consider 
> to be a direct reception.  Change your mobile to WIDE1-1 or 
> WIDE1-1,WIDE2-2 and see if it then shows up in the list.
>
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
>
> On 3/18/2014 3:36 AM, Boardman, Bruce wrote:
>>
>> Andrew,
>>
>> I tried terminating the vehicle transmitter so only I could hear it 
>> locally. The vehicle tracks OK but still no stations heard by?
>>
>> Regards,
>>
>> Bruce Boardman
>> Telstra - Network & Access Technologies
>>
>> cid:image004.jpg at 01CC7EAD.B69AEBF0
>>
>> Ph (02) 8576 7011 <tt:0285767011?Dial>
>> Mob 0427 755 678
>> Telstra Depot
>> Lot2/ 44-58 Duhig St,
>>
>> Harristown QLD 4350
>>
>> *From:*aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] *On 
>> Behalf Of *Andrew Rich
>> *Sent:* Tuesday, 18 March 2014 5:29 PM
>> *To:* TAPR APRS Mailing List
>> *Subject:* Re: [aprssig] IGate issue
>>
>> Could it be that Another Igate is faster than your reports. ?
>>
>> You should run wire shark program on your PC to see packets going to 
>> the internet
>>
>> Andrew
>>
>> Sent from my iPhone
>>
>>
>> On 18 Mar 2014, at 1:16 pm, "Boardman, Bruce" 
>> <Bruce.Boardman at team.telstra.com 
>> <mailto:Bruce.Boardman at team.telstra.com>> wrote:
>>
>>     Andrew,
>>
>>     When you say passcode, I did need a new registration number, and
>>     from that I got a new Validation number which I have entered into
>>     IU View under "APRS server setup". It is connected to the tier 2
>>     server OK. Have a look at my Igate and you will see its working
>>     but no liost like it used to have. Thanks.
>>
>>     Regards,
>>
>>     Bruce Boardman
>>     Telstra - Network & Access Technologies
>>
>>     <image001.png>
>>
>>     Ph (02) 8576 7011 <tt:0285767011?Dial>
>>     Mob 0427 755 678
>>     Telstra Depot
>>     Lot2/ 44-58 Duhig St,
>>
>>     Harristown QLD 4350
>>
>>
>>     *From:*aprssig-bounces at tapr.org <mailto:aprssig-bounces at tapr.org>
>>     [mailto:aprssig-bounces at tapr.org] *On Behalf Of *Andrew P.
>>     *Sent:* Tuesday, 18 March 2014 11:51 AM
>>     *To:* TAPR APRS Mailing List
>>     *Subject:* Re: [aprssig] IGate issue
>>
>>     Did you change your passcode? You changed your callsign, so you
>>     will need a new APRS-IS passcode corresponding to the new callsign.
>>
>>     Contact the author of the software you are using for a new
>>     passcode if you don't have one already.
>>
>>     Andrew Pavlin, KA2DDO
>>     author of YAAC
>>     http://www.ka2ddo.org/ka2ddo/YAAC.html
>>
>>     ------------------------------------------------------------------------
>>
>>     From: Bruce.Boardman at team.telstra.com
>>     <mailto:Bruce.Boardman at team.telstra.com>
>>     To: aprssig at tapr.org <mailto:aprssig at tapr.org>
>>     Date: Tue, 18 Mar 2014 12:45:46 +1100
>>     Subject: [aprssig] IGate issue
>>
>>     Hi,
>>
>>     I recently changed address (to a different state in Australia)
>>     and this necessitated a callsign change. My Igate is now VK4MQ-5
>>     (used to be VK2ZZM-5).
>>
>>     http://aprs.fi/info/a/VK4MQ-5
>>
>>     Since the change I am passing packets RF to internet OK, but I
>>     don't have a "stations heard by" list any more. Also my graphs
>>     show nothing. I tried firing up my mobile tracker on 10MHz so
>>     that only my Igate could hear it, and the packets pass OK but
>>     still no list. Other mobile stations are passing info to me which
>>     I can see from their raw packets.
>>
>>     Looks like an APRS server problem to me, as I have confirmed all
>>     my UI View settings?? Any advice please?
>>
>>     Regards,
>>
>>     Bruce Boardman
>>
>>
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>>
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>>
>>
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>
>
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