A Discussion on NarrowBand Digital Implementation Planning for the 2M Band

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A Discussion on Narrow-Band Digital
Implementation Planning for the 2M Band

• Ray Abe Abraczinskas, W8HVG

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INTRODUCTION

• This is an idea document not a plan!
• Its a seed to plant in an already growing
  garden
• Could be cultivated some more
• Not to imply that the garden isnt being
  cultivated!

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2M BAND PLAN
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2M BAND PLAN continued
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2M BAND PLAN continued
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MARC DOG Resolution 11

• Excellent future-thinking experiment
• MARC is to be congratulated
• Is it the final solution?
• Are there other things to consider in honing it?
• The subject needs to be discussed and analyzed
  further in order to

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Hone the Solution

• 1. Involve the MARC constituency (and the
  surrounding areas)
• 2. Discuss, identify, and quantify problems and
  constraints between analog and N.B. digital
  repeaters (quantify any testing)
• 3. Determine if DOG Resolution 11 can become a
  permanent plan (pros cons)
• 4. Summarize what other states/areas are doing
  (what is and is not working?)

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Hone the Solution continued

• 5. Determine what if any elements can be
  incorporated long-term (the benefits)
• 6. Work towards removing the provisional
  coordination constraints, i.e., have something
  more stable (ultimate goal)
• 7. Determine what frequencies can be designated
  for narrow-band digital repeaters and narrow-band
  simplex in Lower Michigan (and surrounding areas)

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BACKGROUND

• In December 2006, MARC made a provision called
  Resolution 11 under the Development Operational
  Guidelines (DOG) (later modified thru June 2007)
  to coordinate narrow-band digital voice/data
  repeaters in Lower Michigan
• Is it the final solution or are there other
  elements to improve it, or replace it?
• The MARC Board may already know the answers but
  these have not been revealed to the MARC
  constituency

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BACKGROUND continued

• It would seem appropriate that an activity is
  needed for a period of time to address the
  question in a process to be defined and acted
  upon by a cadre of supportive hams to assist
  MARC in obtaining an answer
• This activity could augment the on-going DOG
  Resolution 11 experiments and be expanded upon
  in answering the question to the MARC
  membership and the surrounding areas

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BACKGROUND continued

• D-STAR and APCO P25 operation in Michigan over
  the past 20-months has probably yielded valuable
  experience to a limited number of hams - and
  thats great!
• Where willing and able, those knowledgeable hams
  would be a valuable asset in continuing leading
  and/or assisting in the above discussions and
  determinations

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BACKGROUND continued

• At this stage of DOG Resolution 11 provisional
  experiments, there must be many more interested
  and supportive hams in the MARC constituency that
  would be willing to assist in addressing the
  question and seeking answers (several I know are
  willing to try along with myself)

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BASIC GOALS TO ADDRESS

• Get expanded involvement of 2M repeater
  owners/trustees aiding the MARC (explore and
  promote involvement which could aid buy-in by the
  entire MARC constituency
• MARC brief the status to interested constituency
  hams (educate)
• Clear up the paper repeater issue to get the
  real picture (focus)
• Identify singly owned multiple repeaters covering
  same areas.

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BASIC GOALS TO ADDRESS

• Identify repeaters in the same area with
  overlapping coverage
• Identify repeaters with little activity
• Identify the non-coordinated repeaters operating
  in Lower Michigan
• Explore and identify repeaters willing to
  implement narrow-band digital operation in place
  of analog

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BASIC GOALS TO ADDRESS

• Explore, draft, and negotiate agreements to make
  provisions
• Based on the above results explore finding
  contiguous spectrum holes for dedicated
  narrow-band digital use in the current 20 kHz
  band plan (say, two or three adjacent 20 kHz
  channels)

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BASIC GOALS TO ADDRESS

• Explore the advantages of a 15 kHz band plan for
  contiguous spectrum (even a partial if necessary)
• Compare the on-channel to adjacent channel
  implementation schemes (pros cons of each)
• Strategize the band edges for potential
  narrow-band digital implementation benefits and
  feasibility

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BASIC GOALS TO ADDRESS

• Strategize set frequencies for narrow-band
  digital repeaters and narrow-band digital simplex
  operation
• Analyze the results, iterate, and implement
  useable elements
• Produce a summary document/report that describes
  and/or justifies the total result (post on-line
  for the benefit of others)
• Items that I believe others and I can
  contribute to

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POSSIBILITIES

• Do we need 20 simplex frequencies in Michigan?
  Can the bottom or top five be formalized into a
  band plan of narrow-band digital only channels
  that would yield nine 10 kHz N.B. digital
  repeater channels (high-in, low-out) with a 1 MHz
  offset in Michigan (and surrounding areas)?

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POSSIBILITIES continued

• Scrutinize the digital packet channels to see if
  all are required (poll the packet gurus). Could
  some be utilized for narrow-band digital simplex
  and even become a contiguous narrow-band digital
  spectrum for both N.B. digital simplex and N.B.
  digital repeater inputs?

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POSSIBILITIES continued

• If 10 kHz channel operation is positively
  useable, splintering the packet channels (144.910
  to 145.090) could yield nine N.B. digital
  repeater channels (low-in, high-out with 600 kHz
  offset) and possibly eventually augment the
  existing packet net capabilities in the future.
  N.B. digital would seem to be less traumatic to
  digipeaters. Has the DOG Resolution 11
  experiment tested any packet splinter channel
  interference effects?

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POSSIBILITIES continued

• Could the Miscellaneous Experimental Mode
  channels (145.50 to 145.80 MHz) become formalized
  digital experimental mode channels or at least
  some of them for simplex N.B. digital? 145.61 and
  145.67 are being used for D-STAR simplex now.
  Could the FCC be petitioned to allow narrow-band
  digital repeaters in this spectrum?

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POSSIBILITIES continued

• Invert the D-STAR repeater channels on the
  splinter frequencies to gain 600 kHz isolation
  (vs 10 kHz) in analog user receivers. Has the DOG
  Resolution 11 experiment tested this scheme?
  This has apparently worked OK on the analog
  channels in Michigan for years with surrounding
  states because of their 15 kHz vs 20 kHz band
  plan effects

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CONCLUSION

• Given the above, it seems feasible to have an
  estimated 18-plus new N.B. digital voice and data
  repeater channels and several N.B. digital
  simplex channels in the Michigan 20 kHz band plan
  on a permanent basis compatible with analog
  repeaters without the potential of causing
  interference, and without a risk of having to
  change frequency, all with the added benefit of
  using existing standard coordination procedures
  (and possibly provide the same capabilities for
  the surrounding states)

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CONCLUSION continued

• Can a process addressing the above GOALS
  substantiate the 18-plus narrow-band digital
  repeaters and several narrow-band digital simplex
  channels estimate?
• Does the MARC want to do it?

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THE END

• Comments?
• Questions?
• Discussion?

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A SPLINTER EXAMPLE

• The 147.29 D-STAR transmitter could affect a
  users receiver for two analog repeaters on
  147.28 147.30 in the yellow areas.
• A D-STAR base station in the yellow areas could
  desense HT users of both analog repeaters.
• Inverting the D-STAR repeater may require more
  distance separation but should eliminate ALL user
  interference potential.

147.29
147.28
147.30