[802.3_SPMD] Mixing segment RL (317 & 296) and TCI RL (298)

[George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>]

Michael & Stephan –

I checked the RL losses, and I believe the following will resolve the comments on the RL (mixing segment = 317 & 296 ; MPI loading is 298)

For the overall mixing segment, I used the form that Stephan had, and just ran it down to a new floor that would show minimal loss (0.1 dB), keeping the upper corner at 12.5 MHz:

The equation I come up with is:

19.5-MAX(0,25*log10(F/12.5)  for F > 6.8 MHz				F>cutoff
Max(0.65,.65+30*log10(F/1.6)  for 0.3 < F < 6.8 MHz				.3<F<cutoff

 

This gives a loss in SINR of 0.1 dB.  If you can go all the way down to 20 dB, you can reduce the loss to zero. (preferred).  In this case the corner frequency is 7.07 MHz

 

 

If we want to modify the TCI RL for unit loads, what you want to do is the following:

 

In clause 188.9.2, insert a new first sentence “When the TCI is also an MPI, the return loss of the TCI complies with the return loss of 189.6.1.”  Change the beginning of the following sentence to read, “When the TCI is not an MPI, the TCI return loss at TC1 and TC2 shall meet the values determined using Equation (188–7) with the other trunk TC (i.e., TC2 or TC1, respectively) terminated in 100 /OHMS with a DTE or simulated DTE load present at the TCI.”  (where /OHMS is the symbol for Ohms)

 

 

In clause 189.6, insert new section 189.6.1 MPI Return Loss  with text:

“When the MPI is a TCI, the TCI return loss at TC1 and TC2 shall meet the values determined using Equation (188–7) with the other trunk TC (i.e., TC2 or TC1, respectively) terminated in 100 /OHMS with a DTE or simulated DTE load present at the TCI, plus 10*log10(N_load), where N_load is the maximum number of unit loads for the DTE.  (where /OHMS is the symbol for Ohms)”

 

This should give reasonable losses, since the number of unit loads on a mixing segment is limited to 16.

 

A one-unit-load MPI will be the same as a clause 188 unpowered TCI.

 

What I haven’t done is resimulate the mixing segment RL for cases where one or more of the unit loads are greater than 1.  I suspect we can leave that for the next time.

 

 

George Zimmerman, Ph.D.

President & Principal

CME Consulting, Inc.

Experts in Advanced PHYsical Communications

george@xxxxxxxxxxxxxxxxxxxx

310-920-3860

 

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