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Re: [aprsisce] GPRMC sentence in packet

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  • Lynn W Deffenbaugh (Mr)
    The packet has to pass parse. I m not sure just what all elements might be required in order to do that. Are you planning to construct one of these manually?
    Message 1 of 5 , Feb 13, 2013
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      The packet has to pass parse. I'm not sure just what all elements might
      be required in order to do that.

      Are you planning to construct one of these manually? If so, why not
      just do a normal APRS posit packet?

      Or do you have a GPS that's going nuts and not fully fleshing out an
      NMEA sentence?

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

      On 2/13/2013 1:10 PM, Fred Hillhouse wrote:
      > How much of the GPRMC sentence must be present?
      >
      > Assuming the checksum is correct, can any of the fields, such as time, be
      > empty?
      >
      > Thanks!
      > Fred, N7FMH
      >
      >
      >> -----Original Message-----
      >> From: aprsisce@yahoogroups.com
      >> [mailto:aprsisce@yahoogroups.com] On Behalf Of Lynn W Deffenbaugh (Mr)
      >> Sent: Wednesday, February 13, 2013 12:58
      >> To: aprsisce@yahoogroups.com
      >> Subject: Re: [aprsisce] GPRMC sentence in packet
      >>
      >> (Note: Wiki fodder below, but I don't know exactly where....
      >> Maybe a FAQ?)
      >>
      >> APRSISCE/32 implements the aprs101.pdf-specified method of
      >> determining a symbol. Namely (from Chapter 20):
      >>
      >>> There are three methods of specifying an APRS symbol (display icon):
      >>> . In the AX.25 Information field.
      >>> . In the AX.25 Destination Address.
      >>> . In the SSID of the AX.25 Source Address.
      >>> The preferred method is to include the symbol in the
      >> Information field.
      >>> However, where this is not possible (for example, in stand-alone
      >>> trackers with no means of introducing the symbol into the
      >> The first and preferred method is obvious: the packet
      >> explicitly tells you the symbols.
      >>
      >> The second is nearly as good in that it provides access to
      >> nearly all of the symbols:
      >>
      >>> . GPSxyz - for generic Destination addresses containing symbols.
      >>> . GPSCnn or GPSEnn
      >> The third would be used for your sample packets which use the
      >> completely generic >APRS destination:
      >>
      >>> SSID-Specified Icons in the AX.25 Source Address Field SSID
      >> Icon SSID
      >>> Icon -0 [no icon] -8 Ship (power boat)
      >>> -1 Ambulance -9 Car
      >>> -2 Bus -10 Motorcycle
      >>> -3 Fire Truck -11 Balloon
      >>> -4 Bicycle -12 Jeep
      >>> -5 Yacht -13 Recreational Vehicle
      >>> -6 Helicopter -14 Truck
      >>> -7 Small Aircraft -15 Van
      >> In your case, AE0SS-11 would be given a balloon symbol. This
      >> is usually the source of some pretty random symbols when the
      >> first (or only)
      >> packet(s) received from a station are not posits. Such
      >> stations will typically have a symbol based on their -SSID
      >> which will then change to their intended symbol when a posit
      >> is (hopefully eventually) received containing a symbol.
      >>
      >> APRSISCE/32 trumps the remembered symbol based on priority
      >> across the three symbol choices as well. This provides for
      >> the -SSID-implied symbol to be finally overridden when a
      >> posit is received.
      >>
      >> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
      >>
      >> On 2/13/2013 12:27 PM, Fred Hillhouse wrote:
      >>> Greetings,
      >>>
      >>>
      >>> In the past, packets like those following might have been received.
      >>> How was the symbol determined? Does it rely on the SSID for
      >> a symbol?
      >>>
      >> AE0SS-11>APRS:$GPRMC,151447,A,4034.5189,N,10424.4955,W,6.474,132.5,220
      >>> AE0SS-11>406,10
      >>> .1,E*58
      >>>
      >> KC0YA-11>APRS:$GPRMC,145322,A,4034.3765,N,10410.8083,W,12.062,220.7,22
      >>> KC0YA-11>0406,9
      >>> .9,E*56
      >>>
      >>> What does APRSISCE do?
      >>>
      >>> I don't believe I have ever noticed a packet of this type
      >> in a long time.
      >>> Thanks!
      >>>
      >>>
      >>> Best regards,
      >>>
      >>> Fred, N7FMH
      >>>
      >>>
      >>>
      >>> ------------------------------------
      >>>
      >>> Yahoo! Groups Links
      >>>
      >>>
      >>>
      >>>
      >>
      >>
      >> ------------------------------------
      >>
      >> Yahoo! Groups Links
      >>
      >>
      >>
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
    • Fred Hillhouse
      Nothing bad like a flaky GPS. I am just playing a bit. I can make a better packet, but for something quick and dirty, I can make a real simple packet and
      Message 2 of 5 , Feb 13, 2013
      • 0 Attachment
        Nothing bad like a flaky GPS. I am just playing a bit. I can make a better packet, but for something quick and dirty, I can make a real simple packet and inject it into APRSIS32. Mainly, I saw the example and was wanting to try it.
         
        Thanks!
        Fred, N7FMH
         


        From: aprsisce@yahoogroups.com [mailto:aprsisce@yahoogroups.com] On Behalf Of Lynn W Deffenbaugh (Mr)
        Sent: Wednesday, February 13, 2013 13:28
        To: aprsisce@yahoogroups.com
        Subject: Re: [aprsisce] GPRMC sentence in packet

         

        The packet has to pass parse. I'm not sure just what all elements might
        be required in order to do that.

        Are you planning to construct one of these manually? If so, why not
        just do a normal APRS posit packet?

        Or do you have a GPS that's going nuts and not fully fleshing out an
        NMEA sentence?

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

        On 2/13/2013 1:10 PM, Fred Hillhouse wrote:
        > How much of the GPRMC sentence must be present?
        >
        > Assuming the checksum is correct, can any of the fields, such as time, be
        > empty?
        >
        > Thanks!
        > Fred, N7FMH
        >
        >
        >> -----Original Message-----
        >> From: aprsisce@yahoogroups.com
        >> [mailto:aprsisce@yahoogroups.com] On Behalf Of Lynn W Deffenbaugh (Mr)
        >> Sent: Wednesday, February 13, 2013 12:58
        >> To: aprsisce@yahoogroups.com
        >> Subject: Re: [aprsisce] GPRMC sentence in packet
        >>
        >> (Note: Wiki fodder below, but I don't know exactly where....
        >> Maybe a FAQ?)
        >>
        >> APRSISCE/32 implements the aprs101.pdf-specified method of
        >> determining a symbol. Namely (from Chapter 20):
        >>
        >>> There are three methods of specifying an APRS symbol (display icon):
        >>> . In the AX.25 Information field.
        >>> . In the AX.25 Destination Address.
        >>> . In the SSID of the AX.25 Source Address.
        >>> The preferred method is to include the symbol in the
        >> Information field.
        >>> However, where this is not possible (for example, in stand-alone
        >>> trackers with no means of introducing the symbol into the
        >> The first and preferred method is obvious: the packet
        >> explicitly tells you the symbols.
        >>
        >> The second is nearly as good in that it provides access to
        >> nearly all of the symbols:
        >>
        >>> . GPSxyz - for generic Destination addresses containing symbols.
        >>> . GPSCnn or GPSEnn
        >> The third would be used for your sample packets which use the
        >> completely generic >APRS destination:
        >>
        >>> SSID-Specified Icons in the AX.25 Source Address Field SSID
        >> Icon SSID
        >>> Icon -0 [no icon] -8 Ship (power boat)
        >>> -1 Ambulance -9 Car
        >>> -2 Bus -10 Motorcycle
        >>> -3 Fire Truck -11 Balloon
        >>> -4 Bicycle -12 Jeep
        >>> -5 Yacht -13 Recreational Vehicle
        >>> -6 Helicopter -14 Truck
        >>> -7 Small Aircraft -15 Van
        >> In your case, AE0SS-11 would be given a balloon symbol. This
        >> is usually the source of some pretty random symbols when the
        >> first (or only)
        >> packet(s) received from a station are not posits. Such
        >> stations will typically have a symbol based on their -SSID
        >> which will then change to their intended symbol when a posit
        >> is (hopefully eventually) received containing a symbol.
        >>
        >> APRSISCE/32 trumps the remembered symbol based on priority
        >> across the three symbol choices as well. This provides for
        >> the -SSID-implied symbol to be finally overridden when a
        >> posit is received.
        >>
        >> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
        >>
        >> On 2/13/2013 12:27 PM, Fred Hillhouse wrote:
        >>> Greetings,
        >>>
        >>>
        >>> In the past, packets like those following might have been received.
        >>> How was the symbol determined? Does it rely on the SSID for
        >> a symbol?
        >>>
        >> AE0SS-11>APRS:$GPRMC,151447,A,4034.5189,N,10424.4955,W,6.474,132.5,220
        >>> AE0SS-11>406,10
        >>> .1,E*58
        >>>
        >> KC0YA-11>APRS:$GPRMC,145322,A,4034.3765,N,10410.8083,W,12.062,220.7,22
        >>> KC0YA-11>0406,9
        >>> .9,E*56
        >>>
        >>> What does APRSISCE do?
        >>>
        >>> I don't believe I have ever noticed a packet of this type
        >> in a long time.
        >>> Thanks!
        >>>
        >>>
        >>> Best regards,
        >>>
        >>> Fred, N7FMH
        >>>
        >>>
        >>>
        >>> ------------------------------------
        >>>
        >>> Yahoo! Groups Links
        >>>
        >>>
        >>>
        >>>
        >>
        >>
        >> ------------------------------------
        >>
        >> Yahoo! Groups Links
        >>
        >>
        >>
        >
        >
        > ------------------------------------
        >
        > Yahoo! Groups Links
        >
        >
        >
        >

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