Thanks, Marty. Those are all good points that I’m sure the EC will take into account.

We have an additional ace in the hole, namely that a footnote to the domestic Table of Frequency Allocations, US 128, limits non-Federal services in the band to the amateur, amateur-satellite, and radiolocation services.

73,

Dave K1ZZ

From: Woll, Marty, N6VI
Sent: Thursday, March 27, 2014 4:49 PM
To: Sumner, Dave, K1ZZ; arrl-odv
Subject: Input for EC re RM-11715

Hi, Dave.

I have received several comments from active microwave operators concern RM-11715, Mimosa Networks’ proposal for Part 90 use of our 10 GHz band/  I request that the Executive Committee consider these comments in formulating a position on that proposal for submission to the FCC.

The overarching concern, of course, is the potential for harmful interference and the inadequacy of Mimosa’s proposed protective measures.  The proposed combination of high power and low-gain antennas is also troubling, as is the range of point-to-multipoint services to which this amendment to Part 90 could apply.

Specific points made in the users’ comments include:

1) Considering the weak-signal nature of our use of these frequencies, the contention-based protocol discussed in Mimosa’s proposal (listen before talk) is not realistic. They could not tell when we are monitoring a frequency or trying to copy a distant signal.  Thus, our only real protection is the proposed band plan (Appendix B) setting aside 10.35 GHz to 10.37 GHz, "Amateur Calling Band" and 10.45 GHz to 10.50 GHz "Amateur Satellite."  We would, in effect, lose the rest of the 10 GHz band permanently.

(2) The Mimosa proposed band plan sets aside 10350-10370 as the amateur calling band and allocates 10370-10390 as channel 18 for Part 90 use. The spillover from the proposed channel 18 is dangerously close to amateur weak signal work at 10368.  We should, at a minimum, push for protecting 10350-10390 (two 'channels' that taken together are well centered around the main amateur activity, instead of only one protected channel that is way off center from the main amateur weak-signal activity).

(3) In Southern California we have active ATV repeaters with inputs around 10400, using 27 MHz-wide NTSC FM.  Mimosa’s channels 18 and 19 could create significant interference to those repeaters, which only listen and do not transmit there.

(4) Mimosa seeks complete freedom in antenna design and a high EIRP. They should be required to limit high EIRP to very-narrow-beamwidth antennas for spatial sharing of spectrum. We (and the proposed multitude of new Part 90 users) would coexist better if narrow beams are the only way that high EIRPs are permitted. We don't want a 360 degree azimuth pattern antenna putting out high power in all directions. Wide coverage patterns should have much lower EIRPs. A point to point backhaul link with a 40 dBi or more antenna might be justified in sending tens of Watts in 1 degree of azimuth in the middle of a several rain storm, if it ran 20 dB lower power the other 99.9% of the time. But a wide area network 360 degree access point should use vastly lower EIRP.

5) Those of us on the band often see significant fading over the course of a day, particularly in the summertime.  One repeater / beacon operator reports that 10 GHz signals to and from his site can go through 4 fades in less than 5 minutes during the summer.  He believes that, if Mimosa does their homework on the 3 cm band they will find that long hops over 10 miles will not be reliable enough for commercial purposes unless they make a massive investment in sites and equipment.

Finally, as Brennan pointed out last fall (ODV-21962), Mimosa’s proposal is inconsistent with WARC-15 Agenda Item 1.12.  It probably wouldn’t hurt us to point that out.

73,

Marty N6VI