| Home |
| Search |
| Today's Posts |
|
#2
July 9th 03, 10:08 AM
|
|||
|
|||
In article , Jack Twilley
writes [This message was reposted from eHam.net's APRS forum by the author] I'm writing an APRS client in Ruby, so I've spent a lot of time staring at packets. I think I understand how RELAY works -- whatever station repeats RELAY packets replaces RELAY with their callsign. WIDE works the same way, but what about WIDEN-n? I've collected some packets with my AEA TNC to demonstrate my confusion. Callsign substitution when using RELAY and WIDE is probably not the norm. KE6STHW6CX-3*WIDESWRRSR:'1PQ!68k/]"4%}Sione KE6STHW6CX-3W6CO-5*SWRRSR:'1PQ!68k/]"4%}Sione In this case, WIDE is being replaced with W6CO-5 when that station repeats the packet. That makes perfect sense. K6HG-9*WIDE2-1S7RURP:'2]1l sk/]"3q} K6HG-9WIDE2*S7RURP:'2]1l sk/]"3q} What station is repeating this packet? I can't tell. What's supposed to happen here? There are two implementations of WIDEn-N - 1. (In Kantronics UIFLOOD terminology, this is ID.) The digipeating station decrements the SSID of the WIDEn-N alias, inserts its own callsign/alias, with the 'H' bit set, before the WIDEn-N, and removes any previous alias immediately before the WIDEn-N. The idea being that the callsign/alias of the last digipeater is shown. So, if DIGI1 and DIGI2 are two digis supporting WIDEn-N, and G4IDE sends a frame via WIDE3-3, you get this - G4IDEAPRS,WIDE3-3:Hello world G4IDEAPRS,DIGI1*,WIDE3-2:Hello world G4IDEAPRS,DIGI2*,WIDE3-1:Hello world 2. (In Kantronics UIFLOOD terminology, this is NOID.) The digipeating station decrements the SSID of the WIDEn-N alias, it does not insert its own callsign/alias, or remove any previous alias. So, if DIGI1 and DIGI2 are two digis supporting WIDEn-N, and G4IDE sends a frame via WIDE3-3, you get this - G4IDEAPRS,WIDE3-3:Hello world G4IDEAPRS,WIDE3-2:Hello world G4IDEAPRS,WIDE3-1:Hello world Mixing the two can result in misleading information. -- Roger Barker, G4IDE - For UI-View go to - http://www.UI-View.com For WinPack go to - http://www.peaksys.co.uk |
|
#3
July 9th 03, 10:08 AM
|
|||
|
|||
|
In article , Jack Twilley
writes [This message was reposted from eHam.net's APRS forum by the author] I'm writing an APRS client in Ruby, so I've spent a lot of time staring at packets. I think I understand how RELAY works -- whatever station repeats RELAY packets replaces RELAY with their callsign. WIDE works the same way, but what about WIDEN-n? I've collected some packets with my AEA TNC to demonstrate my confusion. Callsign substitution when using RELAY and WIDE is probably not the norm. KE6STHW6CX-3*WIDESWRRSR:'1PQ!68k/]"4%}Sione KE6STHW6CX-3W6CO-5*SWRRSR:'1PQ!68k/]"4%}Sione In this case, WIDE is being replaced with W6CO-5 when that station repeats the packet. That makes perfect sense. K6HG-9*WIDE2-1S7RURP:'2]1l sk/]"3q} K6HG-9WIDE2*S7RURP:'2]1l sk/]"3q} What station is repeating this packet? I can't tell. What's supposed to happen here? There are two implementations of WIDEn-N - 1. (In Kantronics UIFLOOD terminology, this is ID.) The digipeating station decrements the SSID of the WIDEn-N alias, inserts its own callsign/alias, with the 'H' bit set, before the WIDEn-N, and removes any previous alias immediately before the WIDEn-N. The idea being that the callsign/alias of the last digipeater is shown. So, if DIGI1 and DIGI2 are two digis supporting WIDEn-N, and G4IDE sends a frame via WIDE3-3, you get this - G4IDEAPRS,WIDE3-3:Hello world G4IDEAPRS,DIGI1*,WIDE3-2:Hello world G4IDEAPRS,DIGI2*,WIDE3-1:Hello world 2. (In Kantronics UIFLOOD terminology, this is NOID.) The digipeating station decrements the SSID of the WIDEn-N alias, it does not insert its own callsign/alias, or remove any previous alias. So, if DIGI1 and DIGI2 are two digis supporting WIDEn-N, and G4IDE sends a frame via WIDE3-3, you get this - G4IDEAPRS,WIDE3-3:Hello world G4IDEAPRS,WIDE3-2:Hello world G4IDEAPRS,WIDE3-1:Hello world Mixing the two can result in misleading information. -- Roger Barker, G4IDE - For UI-View go to - http://www.UI-View.com For WinPack go to - http://www.peaksys.co.uk |
|
#4
July 10th 03, 06:25 AM
|
|||
|
|||
|
"Roger Barker" wrote in message
... snip Callsign substitution when using RELAY and WIDE is probably not the norm. Though not yet universal, callsign substitution is _quite_ common in my area, where many are using Kantronics or PacComm TNCs. K6HG-9*WIDE2-1S7RURP:'2]1l sk/]"3q} K6HG-9WIDE2*S7RURP:'2]1l sk/]"3q} What station is repeating this packet? I can't tell. What's supposed to happen here? These two packets were sent by a couple of high-elevation WIDEn-N digipeaters on mountaintops ringing the SF Bay area. There are two implementations of WIDEn-N - snip Mixing the two can result in misleading information. NOID is far better for determining network topology, and is recommended. This recommendation is by, not least of all, the Father of APRS, Bob WB4APR, who worked with Kantronics to enable the WIDEn-N protocol in the first place, and the guy whose idea WIDEn-N was. http://www.dididahdahdidit.com/text/digis.txt (explanation) http://www.dididahdahdidit.com/ (general APRS info) Hope this helps. 73, Cap KE6AFE |
|
#5
July 10th 03, 06:25 AM
|
|||
|
|||
|
"Roger Barker" wrote in message
... snip Callsign substitution when using RELAY and WIDE is probably not the norm. Though not yet universal, callsign substitution is _quite_ common in my area, where many are using Kantronics or PacComm TNCs. K6HG-9*WIDE2-1S7RURP:'2]1l sk/]"3q} K6HG-9WIDE2*S7RURP:'2]1l sk/]"3q} What station is repeating this packet? I can't tell. What's supposed to happen here? These two packets were sent by a couple of high-elevation WIDEn-N digipeaters on mountaintops ringing the SF Bay area. There are two implementations of WIDEn-N - snip Mixing the two can result in misleading information. NOID is far better for determining network topology, and is recommended. This recommendation is by, not least of all, the Father of APRS, Bob WB4APR, who worked with Kantronics to enable the WIDEn-N protocol in the first place, and the guy whose idea WIDEn-N was. http://www.dididahdahdidit.com/text/digis.txt (explanation) http://www.dididahdahdidit.com/ (general APRS info) Hope this helps. 73, Cap KE6AFE |
|
#6
July 10th 03, 07:17 AM
|
|||
|
|||
|
=2D----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 "Cap" =3D=3D Cap Pennell writes: Roger Callsign substitution when using RELAY and WIDE is probably not Roger the norm. Cap Though not yet universal, callsign substitution is _quite_ common Cap in my area, where many are using Kantronics or PacComm TNCs. [...] Can you explain this behavior? I'm pretty sure the mobile station doesn't have a WIDE alias. KB5WIA*WIDE2-1APRS:$GPGLL,3759.519,N,12218.458,W,232104,A*3A KB5WIA*WIDE2APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A Roger There are two implementations of WIDEn-N - [...] Roger Mixing the two can result in misleading information. Cap NOID is far better for determining network topology, and is Cap recommended. This recommendation is by, not least of all, the Cap Father of APRS, Bob WB4APR, who worked with Kantronics to enable Cap the WIDEn-N protocol in the first place, and the guy whose idea Cap WIDEn-N was. Bob asserts that it's more important to know where the station entered the network in order to estimate the station's position. I'm not sure I agree. However, I can get what I want by using TRACEn-N instead of WIDEn-N, so all is good. I have another question for you, Cap, which is slightly related to a message you sent to a mailing list but which also probably interests people outside that list. I would like to change my fixed home station's routing from RELAY,WIDE (which is bad but works) to specific stations. What is the best way to identify a good path? I'm hoping for something more sophisticated than "listen for stations that identify themselves as WIDE and that you can hear directly", but if that's the right answer, that's good to know. Jack. =2D --=20 Jack Twilley jmt at twilley dot org http colon slash slash www dot twilley dot org slash tilde jmt slash =2D----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE/DQT5GPFSfAB/ezgRAurZAKDNBsCtEBbu3/8mXwJ4XyAzeCiMkgCfW9ui LPI46wCJEgqmG36xQUMAdvM=3D =3DRmFw =2D----END PGP SIGNATURE----- |
|
#7
July 10th 03, 07:17 AM
|
|||
|
|||
|
=2D----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 "Cap" =3D=3D Cap Pennell writes: Roger Callsign substitution when using RELAY and WIDE is probably not Roger the norm. Cap Though not yet universal, callsign substitution is _quite_ common Cap in my area, where many are using Kantronics or PacComm TNCs. [...] Can you explain this behavior? I'm pretty sure the mobile station doesn't have a WIDE alias. KB5WIA*WIDE2-1APRS:$GPGLL,3759.519,N,12218.458,W,232104,A*3A KB5WIA*WIDE2APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A Roger There are two implementations of WIDEn-N - [...] Roger Mixing the two can result in misleading information. Cap NOID is far better for determining network topology, and is Cap recommended. This recommendation is by, not least of all, the Cap Father of APRS, Bob WB4APR, who worked with Kantronics to enable Cap the WIDEn-N protocol in the first place, and the guy whose idea Cap WIDEn-N was. Bob asserts that it's more important to know where the station entered the network in order to estimate the station's position. I'm not sure I agree. However, I can get what I want by using TRACEn-N instead of WIDEn-N, so all is good. I have another question for you, Cap, which is slightly related to a message you sent to a mailing list but which also probably interests people outside that list. I would like to change my fixed home station's routing from RELAY,WIDE (which is bad but works) to specific stations. What is the best way to identify a good path? I'm hoping for something more sophisticated than "listen for stations that identify themselves as WIDE and that you can hear directly", but if that's the right answer, that's good to know. Jack. =2D --=20 Jack Twilley jmt at twilley dot org http colon slash slash www dot twilley dot org slash tilde jmt slash =2D----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE/DQT5GPFSfAB/ezgRAurZAKDNBsCtEBbu3/8mXwJ4XyAzeCiMkgCfW9ui LPI46wCJEgqmG36xQUMAdvM=3D =3DRmFw =2D----END PGP SIGNATURE----- |
|
#8
July 10th 03, 05:48 PM
|
|||
|
|||
|
In article , Jack Twilley
writes "Roger" == Roger Barker writes: Jack Can you explain this behavior? I'm pretty sure the mobile Jack station doesn't have a WIDE alias. Jack KB5WIA*WIDE2-1APRS:$GPGLL,3759.519,N,12218.458,W,232104,A*3A Jack KB5WIA*WIDE2APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A Roger KB5WIA has sent a frame, presumably - Roger KB5WIAAPRS,WIDE2-2:Etc... Roger and it has been digipeated by two WIDEn-N digis. That would make sense except for the asterisks. Roger The only slightly unusual thing about it is that most Roger implementations of WIDEn-N, including Kantronics, will set the Roger 'H' bit when the SSID is decremented to zero. With an Roger AEA/Timewave TNC, which is what you appear to be using, the Roger frame from the final WIDEn-N would be monitored as - Roger KB5WIA*WIDE2*APRS:$GPGLL,3759.519,N,12218.458,W, 232104,A*3A Roger (the difference is the '*' after the WIDE2) None of the ~180k packets I have have two asterisks. Sorry, typo. For a frame header decoded by an AEA/Timewave TNC, it should of course have been - KB5WIAWIDE2*APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A The main point being, that, as I said, most WIDEn-N digis set the 'H' bit when the SSID is decremented to zero. -- Roger Barker, G4IDE - For UI-View go to - http://www.UI-View.com For WinPack go to - http://www.peaksys.co.uk |
|
#9
July 10th 03, 05:48 PM
|
|||
|
|||
|
In article , Jack Twilley
writes "Roger" == Roger Barker writes: Jack Can you explain this behavior? I'm pretty sure the mobile Jack station doesn't have a WIDE alias. Jack KB5WIA*WIDE2-1APRS:$GPGLL,3759.519,N,12218.458,W,232104,A*3A Jack KB5WIA*WIDE2APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A Roger KB5WIA has sent a frame, presumably - Roger KB5WIAAPRS,WIDE2-2:Etc... Roger and it has been digipeated by two WIDEn-N digis. That would make sense except for the asterisks. Roger The only slightly unusual thing about it is that most Roger implementations of WIDEn-N, including Kantronics, will set the Roger 'H' bit when the SSID is decremented to zero. With an Roger AEA/Timewave TNC, which is what you appear to be using, the Roger frame from the final WIDEn-N would be monitored as - Roger KB5WIA*WIDE2*APRS:$GPGLL,3759.519,N,12218.458,W, 232104,A*3A Roger (the difference is the '*' after the WIDE2) None of the ~180k packets I have have two asterisks. Sorry, typo. For a frame header decoded by an AEA/Timewave TNC, it should of course have been - KB5WIAWIDE2*APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A The main point being, that, as I said, most WIDEn-N digis set the 'H' bit when the SSID is decremented to zero. -- Roger Barker, G4IDE - For UI-View go to - http://www.UI-View.com For WinPack go to - http://www.peaksys.co.uk |
|
#10
July 10th 03, 06:36 PM
|
|||
|
|||
|
=2D----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 "Roger" =3D=3D Roger Barker writes: [... confusion and typos ...] Jack None of the ~180k packets I have have two asterisks. Roger Sorry, typo. For a frame header decoded by an AEA/Timewave TNC, Roger it should of course have been - Roger KB5WIAWIDE2*APRS:$GPGLL,3759.519,N,12218.458,W,2 32104,A*3A Right, but that's not what I saw, which is why I asked. If I had seen that, I would have understood it to be what you explained. Roger The main point being, that, as I said, most WIDEn-N digis set Roger the 'H' bit when the SSID is decremented to zero. I need to reread the AX25 spec until I understand all of the bits. Jack. =2D --=20 Jack Twilley jmt at twilley dot org http colon slash slash www dot twilley dot org slash tilde jmt slash =2D----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE/DaQ8GPFSfAB/ezgRAogVAJwOWxO6ZJuUCVQ9Hw0dCq2ITq50bQCgpyCa dpIqzuapAbXBaXh9DhIrEJU=3D =3DbAjZ =2D----END PGP SIGNATURE----- |
| Reply |
|
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| antenna deal of a lifetime | Antenna | |||
Linear Mode
