Re: Filter Out Objects

Lynn Deffenbaugh

Did I test it?  Yes, that's why I mentioned that you could test it yourself if you used APRSIS32 which includes a filter test capability, but only in a positive sense.

READ the definition of the s filter from the quoted page:

s/pri/alt/over Symbol filter pri = symbols in primary table (| => /)
alt = symbols in alternate table (| => /)
over = overlay character (case sensitive)
For example:
s/->     This will pass all House and Car symbols (primary table)
s//#     This will pass all Digi with or without overlay
s//#/T   This will pass all Digi with overlay of capital "T"

Note that PRIMARY table symbols go after the first FORWARD slash and alternate table (ones that can use overlays) go after the SECOND slash and the overlays go after the THIRD slash and are CaSe SeNsItIvE.

So, if we look at one of the stations you want to get rid of, say N7LOB-10 at and then click on the Raw Packets link, we see that they all come from WINLINK and look like:

2020-03-07 07:23:00 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7IIW-10*071222z4151.  NW11152.  Wa144.950MHz 1200 R5m Winlink Gateway

2020-03-07 07:23:02 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7IIW-11*071223z4206.  NW11152.  Wa144.950MHz 1200 R5m Winlink Gateway
2020-03-07 07:23:03 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7NHC-10*071223z3848.  NW11922.  Wa145.090MHz 1200 R8m Winlink Gateway
2020-03-07 07:23:05 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7TNG-10*071223z4213.  NW12147.  Wa145.050MHz 1200 R5m Winlink Gateway
2020-03-07 07:23:07 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7UHR-10*071223z3841.  NW08952.  Wa145.070MHz 1200 R5m Winlink Gateway
2020-03-07 07:23:08 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7X-10  *071223z4818.  NW12237.  Wa145.630MHz 1200 R5m Winlink Gateway
2020-03-07 07:23:10 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD7ZDO-10*071223z4521.  NW12237.  Wa145.570MHz 1200 R5m Winlink Gateway
2020-03-07 07:23:12 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD8THX-10*071223z4246.  NW08607.  Wa145.070MHz 1200 R5m Winlink Gateway
2020-03-07 07:23:14 EST: WINLINK>APWL2K,TCPIP*,qAS,WLNK:;KD8VAJ-10*071223z3908.  NW08432.  Wa145.010MHz 1200 R5m Winlink Gateway

But APRSIS32 makes this easier by showing:

1200 R5m Winlink Gateway

Freq: 145.630MHz
Sym: WinLink (Wa)
App: WinAPRS, etc (L2K)
Ambiguity: 1 nm
FromME: 2659mi NW (311º)
GridSquare: CN86cx
4658.50N 12347.50W
Time: 00-07 11:59:00z
2020-03-07 11:59:16 (18m54s)

Note that the symbol is Wa.  This means alternate table (since the first character isn't /) symbol a with an overlay of W.

Finding one of the DSTAR objects is a bit trickier since they have an embedded space, but if you search for KB7ZEN* in's Raw Packets display, you get:

2020-03-06 21:42:10 EST: KB7ZEN-S>APDG01,TCPIP*,qAC,KB7ZEN-GS:;KB7ZEN B *070242z4656.40ND12236.00Wa/A=000010RNG0001 440 Voice 438.50000MHz +0.0000MHz
2020-03-06 21:42:20 EST: KB7ZEN-B>APDG02,TCPIP*,qAC,KB7ZEN-BS:!4656.40ND12236.00W&/A=000010RNG0001 440 Voice 438.50000MHz +0.0000MHz
2020-03-06 22:03:30 EST: KB7ZEN-S>APDG01,TCPIP*,qAC,KB7ZEN-GS:;KB7ZEN B *070303z4656.40ND12236.00Wa/A=000010RNG0001 440 Voice 438.50000MHz +0.0000MHz
2020-03-06 22:03:40 EST: KB7ZEN-B>APDG02,TCPIP*,qAC,KB7ZEN-BS:!4656.40ND12236.00W&/A=000010RNG0001 440 Voice 438.50000MHz +0.0000MHz
2020-03-06 22:24:50 EST: KB7ZEN-S>APDG01,TCPIP*,qAC,KB7ZEN-GS:;KB7ZEN B *070324z4656.40ND12236.00Wa/A=000010RNG0001 440 Voice 438.50000MHz +0.0000MHz
2020-03-06 22:24:50 EST: KB7ZEN-B>APDG02,TCPIP*,qAC,KB7ZEN-BS:!4656.40ND12236.00W&/A=000010RNG0001 440 Voice 438.50000MHz +0.0000MHz

Which APRSIS32 kindly describes as:

440 Voice 438.50000MHz +0.0000MHz

Sym: DARES (Da)
App: D-Star Gateway (01)
Range: 1mi
FromME: 2604mi NW (311º)
GridSquare: CN86qw +9ft
4656.40N 12236.00W
Time: 00-07 12:09:00z
2020-03-07 12:09:50 (19m24s)

Which is the same alternate table a symbol with an overlay of D.

So plugging alternate table with overlays D and W into the formula for the s filter, we get:


When I put that filter into an APRSIS32 Filter Test window, I get LOTS of packets including:

WinMain:2020-03-07T12:30:40.967 IS[Firenet](Hit(s//a/D (0x440161))) [0]KB9MNM-S>APDG01,TCPIP*,qAC,KB9MNM-GS:;KB9MNM B *071230z4142.26ND08820.07Ea/A=000010RNG0001 440 Voice 445.60000MHz +0.0000MHz WinMain:2020-03-07T12:30:41.026 IS[APRS-IS](Hit(s//a/D (0x440161))) [1]KB9MNM-S>APDG01,TCPIP*,qAC,KB9MNM-GS:;KB9MNM B *071230z4142.26ND08820.07Ea/A=000010RNG0001 440 Voice 445.60000MHz +0.0000MHz WinMain:2020-03-07T12:30:41.429 IS[APRS-IS](Hit(s//a/D (0x440161))) [0]CN8IC-S>APDG01,TCPIP*,qAC,CN8IC-GS:;CN8IC B *071230z3534.20ND00522.20WaRNG0001 440 Voice 438.45000MHz -8.0000MHz WinMain:2020-03-07T12:30:41.479 IS[Firenet](Hit(s//a/D (0x440161))) [1]CN8IC-S>APDG01,TCPIP*,qAC,CN8IC-GS:;CN8IC B *071230z3534.20ND00522.20WaRNG0001 440 Voice 438.45000MHz -8.0000MHz WinMain:2020-03-07T12:30:41.769 IS[Firenet](Hit(s//a/W (0x570161))) [0]WINLINK>APWL2K,TCPIP*,qAS,WLNK:;OE9XRK-10*071230z4716. NW00937. Ea438.000MHz 9600 R5m Winlink Gateway WinMain:2020-03-07T12:30:41.771 IS[Firenet](Hit(s//a/D (0x440161))) [0]DB0DJ-S>APJIO4,TCPIP*,qAC,DB0DJ-GS:;DB0DJ A *021149z4852.70ND00830.45EaRNG0040 1.2 Voice 1298.575MHz -28MHz WinMain:2020-03-07T12:30:41.794 IS[APRS-IS](Hit(s//a/W (0x570161))) [1]WINLINK>APWL2K,TCPIP*,qAS,WLNK:;OE9XRK-10*071230z4716. NW00937. Ea438.000MHz 9600 R5m Winlink Gateway WinMain:2020-03-07T12:30:41.795 IS[APRS-IS](Hit(s//a/D (0x440161))) [1]DB0DJ-S>APJIO4,TCPIP*,qAC,DB0DJ-GS:;DB0DJ A *021149z4852.70ND00830.45EaRNG0040 1.2 Voice 1298.575MHz -28MHz

Which kindly tells me that packets were hitting on both the D and W overlay characters which is confirmed if you use the aprs101.pdf to visually parse the packet data and find the symbol and overlay characters that match.

Further, if I telnet to my local friendly APRS-IS server and set up that filter (see for instructions), I get the following packets:

VK2RBV-S>APDG01,TCPIP*,qAC,VK2RBV-GS:;VK2RBV B *071233z3351.84SD15112.68EaRNG0050 440 Voice 438.77500MHz +5.0000MHz VA2REX-S>APJIO4,TCPIP*,qAC,VA2REX-GS:;VA2REX AD*221404z4500.92ND07350.48WaRNG0020 1.2 Data 1248.50Mhz 128K VA2REX-S>APJIO4,TCPIP*,qAC,VA2REX-GS:;VA2REX B *022035z4500.92ND07350.48WaRNG0040 440 Voice 448.325Mhz - 5Mhz DO9MC-S>APDG01,TCPIP*,qAC,DO9MC-GS:;DO9MC B *071233z5145.32ND00800.88Ea/A=000010RNG0001 440 Voice 439.93750MHz -9.4000MHz WX4EMA-S>APJIO4,TCPIP*,qAC,WX4EMA-GS:;WX4EMA C *061725z3250.15ND08337.97WaRNG0015 2m Voice 145.340 +0.600 MHz WINLINK>APWL2K,TCPIP*,qAS,WLNK:;VE7LAN-10*071233z4921. NW12257. Wa145.070MHz 1200 R5m Winlink Gateway F5ZLG-S>APJIO4,TCPIP*,qAC,F5ZLG-GS:;F5ZLG B *061711z4334.90ND00129.98EaRNG0030 430 Voice 439.925 -9.4 MHz KN6BDP-S>APDG01,TCPIP*,qAC,KN6BDP-GS:;KN6BDP B *071233z5000.00ND00300.00WaRNG0001 440 Voice 438.80000MHz +0.0000MHz

Which you can see (if you've studied aprs101.pdf and can visually parse packets) includes both the D and W overlays of the alternate table a symbol.

So, yes, I've tested the recommended filter in the positive sense.  Testing a negative filter is much harder in that you have to go through a large (I use planet-wide) stream of data and determine that the target packets are NOT present.

So, my challenge to you is did YOU apply and test the negative form of the filter properly?  What makes you believe it "did not work"?  Is it possible that it DID work and SARTRACK is simply displaying stations that it heard before the negative filter was applied?  Did SARTRACK truly apply the negative filter to the upstream APRS-IS server connection?

And if you need help confirming those questions, please inquire on the SARTRACK support list as they are not APRS-general questions.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

PS.  An alternat esymbol to get rid of all packets from WinLink would be -b/WINLINK or -u/APWL2K.  For the DStar gateways, you could use -u/APDG* or -u/APDG01/APDG02.  The trick to filtering APRS-IS is to deterine what common feature is shared by the target stations' packets and NOT shared by desired station packets.

On 3/7/2020 3:15 AM, Jerry N7YGE wrote:

Did not work.  Did you try it and it worked for you?  See below as to the right orientation of the /a for a red diamond.  Yes I am using SARTRACK but all programs have the filter box and is universal.  So should work for all aprs programs.  Please send code tested and works for you.




Blocks all packets using a red diamond (\a) overlaid with DW



Since the diamond is red should it use the \a and not /a?





Thank you.



Jerry N7YGE


From: [] On Behalf Of Lynn Deffenbaugh
Sent: Friday, March 6, 2020 5:49 PM
Subject: Re: [APRSISCE] Filter Out Objects


Nice map, but I don't think that's APRSIS32...  If it was, you could test the positive filter with Control-G for a filter test.  But here's what I think you need:


Yes, there's 2 slashes after the s and one slash after the a.  It says to suppress all "a" symbols from the alternate table (the red diamond) with an overlay of W or D.

You can read more about APRS-IS filters at:

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 3/6/2020 6:14 PM, Jerry N7YGE wrote:

I want all of the red diamond with W and D’s to go away.  Picky any of them.


Thank you for the help.




From: [] On Behalf Of Lynn Deffenbaugh
Sent: Friday, March 6, 2020 12:49 PM
Subject: Re: [APRSISCE] Filter Out Objects


-o is an object filter which is based on the object name.

I suspect you're looking for a -s filter which is a symbol filter.

Please give me a few of the stations you'd like to not see so that I can verify exactly which symbol they're using to build you a suitable -s/ symbol filter.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 3/6/2020 12:22 PM, Jerry N7YGE wrote:


Can someone please show me how to write the code for a filter to be able to turn off objects like winlink with a red diamond and W? Also black diamond with a D.


I have tried  filter –o/a/DW and -0/a\DW


Jerry N7YGE


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