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Selective decoding/ Facility update

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  • graham787
    Selective decoding/ Facility update From 3 August 2011, A new ROS Mode will become active , this mode, now has provision for selective decoding and it will not
    Message 1 of 1 , Aug 1, 2011
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      Selective decoding/ Facility update

      From 3 August 2011, A new ROS Mode will become active , this mode, now has
      provision for selective decoding and it will not be compatible with the
      present ROS Mode.

      A new switch is added, All / `call-signe'
      In position ALL , ROS will decode any message (recommended for SWL operation),

      In position `call-signe' it will only decode transmissions from the
      station with the entered `call-signe'.

      Thus , with two stations in qso, the channel may be used by other
      stations

      NB This facility is only available to the ROS-HF modes , MF and EME
      being FSK based and of very narrow bandwidth, are not afforded this
      facility.

      The single hop digital repeating facility

      The single hop digital repeating facility is also now made avaialble,
      repeating is under the control of the station opertor, who may select
      the mode from the menu, then , station with the pre-fix R- to the
      call Signe will be re radiated , with crc check on the data content .

      This facility may provide , via the cat link, cross band operation , it
      is not intended to replace a full packet network , but provides a
      useful extension to operations in difficult locations and cross linking
      , noting this may also be accessed via the established internet remote
      faction's .

      Of particular interest to those operating under the SS directive.

      On a more finer technical point , one that has to date been some what
      over overlooked , I must admit , I had not noticed this until , looking
      back over some off air captures of 500 khz beacon tests, however I have
      confirmation this is accurate.

      Where as the ros system is distributed as a single .exe file, the
      composition of the ROS EME and MF modes is in actuality fundamentally
      different.

      The MF modes , being unable to take advantage of the BW=Noise gain , the
      coding is restricted to FSK , and is therefore eligible for operation
      within the existing fcc/ss dictates

      Operators are invited to observe a eme or mf mode beacon, using ,
      eg, speclab and it will be noted the transmitted pattern is repeated ,
      demonstrating in the most simple way , that , no randomizer is deployed and
      at 50 and 100 Hz B/W respectfully , clearly the concept of spectral
      dispersion is not applicable.

      This information , I feel will be of interest to those who are genuinely
      involved in the development of data modes as it demonstrates dispersion
      techniques are in fact self limiting , noting that the existing
      directives of 300 baud and ss are not seen to sit comfortably , untill
      other such changes are implemented , this may present a area of development
      ?

      For example the mf-7 mode affords a s/n gain round 10db over the well
      established psk31 , coupled with a total loss of 'gray' noise , due to the
      phase cont modulation schema.

      G..
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