[DLK] FW: Comments and discussion

[Jose Godoy]

Hi Dongsong,

Thank you for the analysis.

My comments:
1 -  SARPs RTCA VDL2 Specifications Comparison - general agreement, no comments
2 - The Part 15 device interference to VDL2 radio analysis is very close to reality.  I walked off 6 paces at one of the sites from interferer to antenna at LAX.
3 - I note that the SARPS uses the dBm unit for field strength only in this case and without notice of the exception.  Additionally, there is no commentary in the SARPS that GS and airborne platforms will have different values for idle/busy.
4 - Note that sections 6.4.3.2 of the SARPS and section 3.2.1.7.of RTCA DO-224 both use "When a station receives on-channel power of at least xx dBm".  The measurement point is "station" yet the levels are different.
5 - Using the same logic previously discussed and starting with the -100 dBm level from DO-224D section 3.2.1.7.1, we should be able perform the similar analysis to get to the -92 dBm level in section 6.4.3.2.1 of the SARPS.  So I can do that for the airborne platform.  For the ground side, we use a 2 dBi antenna and 2 dB cable loss.  This approach leads to a -100 dBm level.  -100 dBm is not equal to -92 dBm.
6 -  I continue to believe that the RTCA and ICAO documents point to different levels for busy/idle.

Let me suggest two discussion points:
1 - Resolve the inconsistency or provide additional clarification for the RTCA and ICAO documents in the busy idle determination area.
2 - The LED issue in conjunction with the Part 15 analysis.
  - Can we raise the busy idle levels in the specs, different levels for on ground and in air, or require the adaptive algorithm?
  - I looked for commercially available flood light shields but did not find anything.  There will be many form factors required.  What about non LED sources?
  - The noise issue is growing and impacts system performance

Thanks,
Ramsey

--



Ramsey Abid / Sr. Principal Engineer / Prod Engr & Development
Information Management Services
2551 Riva Road, Annapolis, MD  21401 USA
Phone: 410-266-2911
ramsey.abid at collins.com<mailto:rfa at arinc.com> | www.collinsaerospace.com<http://www.rockwellcollins.com/>

CONFIDENTIALITY WARNING: This message may contain proprietary and/or privileged information of Collins Aerospace and its affiliated companies. If you are not the intended recipient, please 1) Do not disclose, copy, distribute or use this message or its contents. 2) Advise the sender by return email. 3) Delete all copies (including all attachments) from your computer. Your cooperation is greatly appreciated.


Nothing in this message is intended to constitute an electronic signature unless a specific statement to the contrary is included in this message. Confidentiality Note: This message is intended only for the person or entity to which it is addressed. This email, and any attachments, may contain confidential and/or proprietary material. Any review, transmission, dissemination or other use, or taking of any action in reliance upon this message by persons or entities other than the intended recipient is prohibited. If you received this message in error, please contact the sender and permanently delete any printout of the message, the original and any copy of the e-mail and its attachments from your computer.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.sae-itc.org/pipermail/dlk/attachments/20200723/e45ed718/attachment.html>