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Re: Comments on "Live RMS Packet Station Positions"

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  • la7um
    Sounds interesting. How do you think this will work, (or not?) when being forced using Narrowband FM repeaters, max 2.5.Khz deviation? 73 de LA7UM Finn
    Message 1 of 5 , May 8, 2012
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      Sounds interesting. How do you think this will work, (or not?) when being forced using Narrowband FM repeaters, max 2.5.Khz deviation?
      73 de LA7UM Finn

      --- In LinuxRMS@yahoogroups.com, "ve7fet" <yahoogroups@...> wrote:
      >
      > So, what we have are repeaters (like voice repeaters) that have split audio paths through them, one path goes to the TNC for the local node, and the other path went to a Bell 202 modem to do "regeneration".
      >
      > Worked very well for many years, you can send packet through the repeater without any addressing and effectively connect to stations directly, but with the advantage of having your "transmitter" located up high at the repeater site.
      >
      > If you want to connect to the node at the repeater, you just address your call to it, and it will respond.
      >
      > I say this worked well for many years because as of late our 20-30 year old Bell 202 modems are finally starting to pack it in.
      >
      > As a replacement, what I am now doing is functionally equivalent, but bypassing the Bell 202 "regen" modem.
      >
      > I have built a daughter board that has some audio switches on it that I stuff inside the repeater. It uses COS from the repeater and DCD from the TNC to do AND squelch so that only data can be repeated to prevent abuse by voice operators.
      >
      > There are still two audio paths. The default path takes discriminator audio and loops it directly to the transmitter (direct injection in to the limiter stage AFTER the typical pre-emphasis stage).
      >
      > The TNC in the repeater listens to discriminator audio all the time, so it can provide DCD when it validates data on the channel. When DCD and COS are active, the repeater transmitter is keyed and whatever the receiver is hearing (should be valid packet) is sent to the transmitter... providing the repeat function without the regeneration that used to be provided by the Bell 202.
      >
      > In the other mode, when the TNC wants to transmit, it breaks the path through the repeater (using the audio switches), and its audio is sent out the transmitter.
      >
      > The TNC won't transmit over top of anyone since it has DCD on the repeater input, and the audio path through the repeater is broken when the TNC is transmitting to prevent mixing receiver audio with the TNC's audio (if there is any crud on the receiver it won't garble the data from the TNC).
      >
      > There is also pre-emphasis added to the TNC's transmit audio, since it uses the same injection point as the through path in the repeater, which is after the stock pre-emphasis stage.
      >
      > This setup seems to work well. You get the advantage of a highly situated packet repeater to increase the coverage area, as well as having an integrated node that you can use for things such as RMS, FPAC, FBB, etc.
      >
      > With FPAC running, you can layer all the rest of the utilities on the same platform and connect with other nodes easily to create larger networks.
      >
      > Got a little long winded there... hopefully it all makes sense. :)
      >
      >
      > Lee
      >
      > --- In LinuxRMS@yahoogroups.com, k4rjj@ wrote:
      > >
      > >
      > >
      > > How does that woek beside very well?!  Full duplex like a regular repeater?  What are you broadcasting out to at the same time you are getting data in?  Please give details.  Thnaks!
      > >
      > >
      > >
      > >
      >
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