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Re: [aprsisce] Stale position reports

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  • James Ewen
    ... In the XML file: 120 Affects the time that all stations fade out. 0
    Message 1 of 8 , Apr 21, 2013
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      On Sun, Apr 21, 2013 at 6:47 PM, k7ybz <k7ybz@...> wrote:

      > Is there a means of clearing stale position reports? I would like to see only reports
      > in say the last three or four minutes and purge anything that has not been updated
      > within that time frame.

      In the XML file:

      <Stations.MaxAge>120</Stations.MaxAge>

      Affects the time that all stations fade out.

      <Stations.MaxAge.Buddy>0</Stations.MaxAge.Buddy>

      Affects the time that stations in your buddy list fade out.
      --
      James
      VE6SRV
    • k7ybz
      Thanks James, Somehow my reply did not get through so will do it again. I work on a week long bicycle event and we are not pleased with the results using the
      Message 2 of 8 , May 9, 2013
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        Thanks James,

        Somehow my reply did not get through so will do it again.

        I work on a week long bicycle event and we are not pleased with the results using the national APRS frequency and we do not want to spam it either. We were using smartbeaconing but oftentimes beacons were never received or clobbered. When we have a vehicle we KNOW is moving but the icon shows stationary, the position report is useless for an emergency.

        Since one of three net control stations has comms with the stations in that net's area, we are planning on moving to an alternate frequency from APRS. We will have the stations time slotted as best we can. Unfortunately, the slotting on most units is by the minute and we really need it by seconds or 10s of seconds. We have up to 15 vehicles we track throughout the daily course (the course is different each day). We need almost real time position reports but we can live with two minutes.

        It would be "nice" if there were a means of a net control station actually "polling" each of the vehicles in sequence every minute or continuously. That way we have the most current status and position. Unfortunately, I know of no means in the HAM arena to do that. From what I have researched, that can be done in the commercial arena, but we do not have the budget for anything like that.

        We will put the APRS rigs on their own bandpass filters tuned to the frequency we are using to minimize de-sense by the other net comms (Medic, Staff, Course, SAG, and two private). Medic, Course, and SAG all have their own bandpass filters.

        I sent a private email to Lynn about this but I know he is very busy.

        Larry
        K7YBZ

        --- In aprsisce@yahoogroups.com, James Ewen <ve6srv@...> wrote:
        >
        > On Sun, Apr 21, 2013 at 6:47 PM, k7ybz <k7ybz@...> wrote:
        >
        > > Is there a means of clearing stale position reports? I would like to see only reports
        > > in say the last three or four minutes and purge anything that has not been updated
        > > within that time frame.
        >
        > In the XML file:
        >
        > <Stations.MaxAge>120</Stations.MaxAge>
        >
        > Affects the time that all stations fade out.
        >
        > <Stations.MaxAge.Buddy>0</Stations.MaxAge.Buddy>
        >
        > Affects the time that stations in your buddy list fade out.
        > --
        > James
        > VE6SRV
        >
      • Robert Bruninga
        Proper APRS design is for a channel loading of 20% max. If you have 15 stations and ONE digipeat, then that is 30 packets. Then divide that by 20% and you get
        Message 3 of 8 , May 9, 2013
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          Proper APRS design is for a channel loading of 20% max. If you have 15
          stations and ONE digipeat, then that is 30 packets. Then divide that by
          20% and you get 150 seconds or about once every 2.5 minutes.

          If *all* of the stations have RECEIVERS and if all of them can hear *every
          other mobile* (very rare) then you can double that to one packet every 75
          seconds per station and still have good throughput.

          Making every packet go 2 hops, and using one-way TXC only trackers will
          make things worse.

          Smart Beaconing might not be a good idea where tracking reliability is
          important since it reduces redundancy and makes each single packet more
          important. In APRS where you have a good probability of lost packet, then
          smart-beaconing will be less reliable.

          Operating with a single hop throughout the event will DOUBLE throughput if
          you operate split with all mobiles transmitting on +600 from the
          digipeater outputs. This works well as long as a single hop though any
          digipeater is sufficient for the goals of the system.

          Bob, WB4aPR


          -----Original Message-----
          From: aprsisce@yahoogroups.com [mailto:aprsisce@yahoogroups.com] On Behalf
          Of k7ybz
          Sent: Thursday, May 09, 2013 3:05 PM
          To: aprsisce@yahoogroups.com
          Subject: [aprsisce] Re: Stale position reports

          Thanks James,

          Somehow my reply did not get through so will do it again.

          I work on a week long bicycle event and we are not pleased with the
          results using the national APRS frequency and we do not want to spam it
          either. We were using smartbeaconing but oftentimes beacons were never
          received or clobbered. When we have a vehicle we KNOW is moving but the
          icon shows stationary, the position report is useless for an emergency.

          Since one of three net control stations has comms with the stations in
          that net's area, we are planning on moving to an alternate frequency from
          APRS. We will have the stations time slotted as best we can.
          Unfortunately, the slotting on most units is by the minute and we really
          need it by seconds or 10s of seconds. We have up to 15 vehicles we track
          throughout the daily course (the course is different each day). We need
          almost real time position reports but we can live with two minutes.

          It would be "nice" if there were a means of a net control station actually
          "polling" each of the vehicles in sequence every minute or continuously.
          That way we have the most current status and position. Unfortunately, I
          know of no means in the HAM arena to do that. From what I have researched,
          that can be done in the commercial arena, but we do not have the budget
          for anything like that.

          We will put the APRS rigs on their own bandpass filters tuned to the
          frequency we are using to minimize de-sense by the other net comms (Medic,
          Staff, Course, SAG, and two private). Medic, Course, and SAG all have
          their own bandpass filters.

          I sent a private email to Lynn about this but I know he is very busy.

          Larry
          K7YBZ

          --- In aprsisce@yahoogroups.com, James Ewen <ve6srv@...> wrote:
          >
          > On Sun, Apr 21, 2013 at 6:47 PM, k7ybz <k7ybz@...> wrote:
          >
          > > Is there a means of clearing stale position reports? I would like to
          > > see only reports in say the last three or four minutes and purge
          > > anything that has not been updated within that time frame.
          >
          > In the XML file:
          >
          > <Stations.MaxAge>120</Stations.MaxAge>
          >
          > Affects the time that all stations fade out.
          >
          > <Stations.MaxAge.Buddy>0</Stations.MaxAge.Buddy>
          >
          > Affects the time that stations in your buddy list fade out.
          > --
          > James
          > VE6SRV
          >




          ------------------------------------

          Yahoo! Groups Links
        • k7ybz
          Hi Bob, The only reason we used the smartbeacon is that a vehicle might be stationary for a good portion of the day depending on the course and assignment.
          Message 4 of 8 , May 9, 2013
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            Hi Bob,

            The only reason we used the smartbeacon is that a vehicle "might" be stationary for a good portion of the day depending on the course and assignment. Most of the vehicles are TX only but a few have displays. We really wanted to keep the 'NOISE' to a minimum on the national APRS frequency, but that created other problems. Hence, our desire to move to another frequency.

            We were not intending to set up a DIGI but will not rule that out. The net controls are the ones that need the most current data but only for those stations in their area. The others are 'NICE TO KNOW'. A net will pass a station to the next net for comm on the next net's frequency at a specified position on the course just like ATC from one controller to the next, but the radar covers more than one area. It would be the same for the position reports.

            Larry
            K7YBZ

            --- In aprsisce@yahoogroups.com, Robert Bruninga <bruninga@...> wrote:
            >
            > Proper APRS design is for a channel loading of 20% max. If you have 15
            > stations and ONE digipeat, then that is 30 packets. Then divide that by
            > 20% and you get 150 seconds or about once every 2.5 minutes.
            >
            > If *all* of the stations have RECEIVERS and if all of them can hear *every
            > other mobile* (very rare) then you can double that to one packet every 75
            > seconds per station and still have good throughput.
            >
            > Making every packet go 2 hops, and using one-way TXC only trackers will
            > make things worse.
            >
            > Smart Beaconing might not be a good idea where tracking reliability is
            > important since it reduces redundancy and makes each single packet more
            > important. In APRS where you have a good probability of lost packet, then
            > smart-beaconing will be less reliable.
            >
            > Operating with a single hop throughout the event will DOUBLE throughput if
            > you operate split with all mobiles transmitting on +600 from the
            > digipeater outputs. This works well as long as a single hop though any
            > digipeater is sufficient for the goals of the system.
            >
            > Bob, WB4aPR
          • Lynn W Deffenbaugh (Mr)
            ... APRSISCE/32 supports ?APRSP as a directed query (message addressed to them) which will trigger an immediate transmission of an updated position packet. I
            Message 5 of 8 , May 9, 2013
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              On 5/9/2013 3:04 PM, k7ybz wrote:
              > It would be "nice" if there were a means of a net control station actually "polling" each of the vehicles in sequence every minute or continuously. That way we have the most current status and position. Unfortunately, I know of no means in the HAM arena to do that. From what I have researched, that can be done in the commercial arena, but we do not have the budget for anything like that.

              APRSISCE/32 supports ?APRSP as a directed query (message addressed to
              them) which will trigger an immediate transmission of an updated
              position packet. I didn't invent this, but implemented it according to
              page 77 of aprs101.pdf. I don't know a) how many other APRS clients
              implement it, b) what (if any) APRS-capable radios (Kenwood/Yaesu)
              support it, c) what standalone tracking hardware (T2/3, TT4, KPC, etc)
              do with it, but I can guarantee that transmit-only trackers (TinyTrak3)
              won't even hear the query.

              Case of careful what you ask for, it might already exist, but I also
              know it's not exactly what you're looking for. There is no low overhead
              polling protocol on the APRS RF network. And sending a whole APRS
              message exchange to just to solicit a posit is a bit much.

              But if you DO need an update from a station that supports the ?APRSP,
              then you have a way to ask it for a posit if it is within messaging range.

              Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
            • Tony VE6MVP
              At 01:46 PM 2013-05-09, k7ybz wrote: Your previous posting mention a bicycle event. This sounds quite interesting. ... Could you be a bit more specific as to
              Message 6 of 8 , May 10, 2013
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                At 01:46 PM 2013-05-09, k7ybz wrote:

                Your previous posting mention a bicycle event.  This sounds quite interesting.

                 The only reason we used the smartbeacon is that a vehicle "might" be stationary for a good portion of the day depending on the course and assignment. Most of the vehicles are TX only but a few have displays.

                Could you be a bit more specific as to make and model of your vehicle APRS units?  As I'm sure you're aware being able to listen for a quiet moment before transmitting would be very nice.

                The folks out here in central Alberta are experimenting with the Quiet time setting and ensuring that value is different for each adjacent digipeater.  The idea being that  if two digis hear the same packet and then start transmitting at the exact same time they will clobber each other out for the listeners along the duplicate coverage zone.


                We were not intending to set up a DIGI but will not rule that out.

                Can a single digi at a high point cover the entire course for that day?

                Tony
              • k7ybz
                Tony, What I meant by tx only is that most of the vehicles have a dedicated xcvr with an external tnc for tx position on the APRS freq but yes there is squelch
                Message 7 of 8 , May 10, 2013
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                  Tony,

                  What I meant by tx only is that most of the vehicles have a dedicated xcvr with an external tnc for tx position on the APRS freq but yes there is squelch detect.

                  Those vehicles that do have display capability such as the Garmin 350 or AvMap G5/G6, etc. then they can monitor positions.

                  The TNC's are a mix of anything that works, mostly OT2's and KPC3's.

                  No, on most days a single DIGI would not work and there is insufficient time to drive to a place, setup a digi, then drive to the net control site. The first net operator has to be at their respective site and set up by 6:30 AM. Setup takes an hour and the drive could be two hours from the overnight. The other one or two net operators could be several hours from their site also. Setup requires putting up at least three masts and isopole antennas for the primary frequencies. The rest of the frequencies are handled by magmounts antennas.

                  You have to understand, in order to reach a site to cover a good portion of the course, we have to be on a mountain top but the course could very well be in a canyon. Access to the net site is usually gravel and/or dirt Forest Service roads or private roads, not necessarily paved highways.

                  Larry
                  K7YBZ

                  --- In aprsisce@yahoogroups.com, Tony VE6MVP <tony@...> wrote:
                  >
                  > At 01:46 PM 2013-05-09, k7ybz wrote:
                  >
                  > Your previous posting mention a bicycle event. This sounds quite interesting.
                  >
                  > > The only reason we used the smartbeacon is that a vehicle "might"
                  > > be stationary for a good portion of the day depending on the course
                  > > and assignment. Most of the vehicles are TX only but a few have displays.
                  >
                  > Could you be a bit more specific as to make and model of your vehicle
                  > APRS units? As I'm sure you're aware being able to listen for a
                  > quiet moment before transmitting would be very nice.
                  >
                  > The folks out here in central Alberta are experimenting with the
                  > Quiet time setting and ensuring that value is different for each
                  > adjacent digipeater. The idea being that if two digis hear the same
                  > packet and then start transmitting at the exact same time they will
                  > clobber each other out for the listeners along the duplicate coverage zone.
                  >
                  >
                  > >We were not intending to set up a DIGI but will not rule that out.
                  >
                  > Can a single digi at a high point cover the entire course for that day?
                  >
                  > Tony
                  >
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