FCC Spectrum Management Mistakes: The “Sweet Sixteen” List – Part 3 Hear No RF Evil - See No RF Evil |  |
| FCC Spectrum Management Mistakes: The “Sweet Sixteen” List – Part 3 Posted: 29 Nov 2011 05:25 AM PST
12. Land Mobile "Re-farming:" (1990s-present). By itself not a major league blunder, but more of a "wolf in sheep's clothing" gambit. The basic idea is to halve, and then later halve again, the occupied (RF channel) bandwidth used by individual private land mobile networks, in order to squeeze ever more of them into a very limited amount of spectrum. This kind of action is consistent with the basic FCC practice of just ignoring the laws of physics whenever it suits their administrative needs. There is nothing fundamentally wrong with the concept, except that the compliant licensees will inherit new systems with operating characteristics different from those to which they designed and built their original systems on the (then) wider channels. Private land mobile operations overwhelming use analog FM emissions, and as the bandwidth of an FM channel is progressively narrowed, the inherent signal/noise advantages of FM emissions, compared to envelope-modulated methods, proportionately diminish. By the time the occupied channel is narrowed to the bandwidth of an equivalent AM signal, there are no remaining FM signal/noise advantages over AM. Hence with new "AM performance-equivalent networks," system operators will find themselves with smaller than expected operating radii and an increase in operational noise problems. (Different problems apply to digital land mobile radio systems, which are not considered here.)  Mobile Radio is Still the Backbone of Public Safety 13. "Broadband" Public Safety nationwide interoperability network (2000s-present). This one is more than just an engineering blunder; it's a total system failure! September 11, 2001, showed the glaring deficiencies in our Public Safety first responders' radio networks, especially in the area of interoperability of responders from different agencies under emergency conditions. Commendably the FCC began quickly to develop a plan for a replacement "nationwide broadband interconnect network" for the current fragmented system, including clearing spectrum at 700 MHz to house it. But now September 11, 2011 has passed and as a nation we have produced………. nothing! We've diddled around with "novel economic concepts" for funding the system, to no avail. But we haven't really begun in earnest to design and to build the new system. On the "FCC time table" it would be another 2½ centuries before the US would first land men on the moon! It might just be more productive for a different agency to take on this priority project. "Hey, NASA…………!!!" 14. Digital broadcast radio – "In Band On Channel" (2000s). This really isn't inherently a bad engineering idea, rather more of a botched implementation. Eventually broadcast radio (AM and FM) will need to transition from the analog world to the digital realm, to join just about every other medium of contemporary information transfer. Unfortunately with a huge installed base of radio receivers, comprising a much larger number of receivers than the equivalent installed television receiver base, the "single national transition day" concept that was used with some success for television probably isn't feasible for radio. And there is insufficient unused broadcast radio spectrum to assign to our current broadcasters temporary "second, digital channels," as was done with television. Some sort of simultaneous "dual mode on a single channel" radio transmission scheme is necessary to permit a long time-scale transition before the analog modes sunset. For the simultaneously compatible digital system the FCC chose the Ubiquity IBOC concept, which the manufacturer promoted as "In-Band On Channel." Unfortunately the engineering reality is somewhat different; it's "IBAC, In-Band Adjacent Channels." In both AM and FM band digital modes, digital modulation sidebands on the analog carrier can extend into both first adjacent channels. Spectrum analyzers will demonstrate that presence, and on-air interference complaints corroborate the problems. If, instead of the FCC's administratively "bending" physics to meet its regulatory needs, it had instead planned for the necessary cleared adjacent channel spectrum and made adjustments to currently assigned stations, the concept might have worked from the beginning. Or if it had ordered multiplexing of the programming from all the stations in a particular "city of license" onto a single new digital-only carrier (as is done in satellite radio broadcasting) while continuing with the existing separate analog carriers, the transition to new receivers could have been facilitated. Now ????  FCC Mapping of Broadband Availability – 2010 15. "The Broadband Superhighway" (2000-present). In the words of the late great Ed Sullivan, "this one is really, really big!" Trusting the "big carriers" to develop a physical and operational structure for an affordable nationwide, universal broadband digital network, a capability required today as essential infrastructure in the global economy, the FCC again dropped the ball. The carriers failed to develop a universal network. Today there is no single nationwide broadband highway that extends into most citizens' homes or businesses, or even a plan for one, but rather a patchwork of different high cost (relative to other countries), modest performance transmission methods and services. Now that we are in the fourth quarter of the game with the clock running down, the FCC is ready to play "catch up football" and to begin throwing Hail Mary! passes. But there is still no workable plan. And indeed the FCC (as well as other cognizant federal agencies) still shows almost no interest in the single solution that would meet the requirements: universal basic fiber-to-the-premises networks with sufficient natural operating bandwidth to meet every conceivable future need. Instead they are expediently promoting everything but that solution. Most perniciously, the FCC is casting its hungry eyes upon the RF spectrum on which to do a "quick and dirty" RF implementation, contemplating devouring huge chunks of spectrum for new "broadband" transmission services that could better done on land lines (i.e., there is no justification for supplying RF broadband service to an urban building). If the FCC were in charge of developing a universal, nationwide materials-transportation network for example, they would today be enthusiastically promoting all of the following (and more): mule trains, river canoe traffic, one-shot space cargo missiles, under-sea dolphin delivery systems, etc. They would be involved in everything except clearing land and laying rails or asphalt on it.  GPS Interference Problem Illustrated – GPS Working Group (PDF) 16. LightSquared (present day). "Just when you thought it was safe to go back into the water…..!" This is the matter that precipitated the original visualization of the Sweet Sixteen list. In the year 2000, to its credit the federal government's executive branch opened the (until then) mostly military-oriented Global Positioning Satellite system to the general public and thereby launched an entirely new industry: high accuracy Navigation and Timing. With cheap and useful terrestrial hardware and a reliable and well-maintained fleet of satellites, and especially with secure satellite operating frequencies that could be successfully received over most of the surface of the planet, GPS offers levels of technology, convenience, and service never before available. But even that achievement may not be sufficient to preserve GPS as we have grown to know it. In its mania to develop some kind of "universal broadband" service, the FCC now stands ready to sacrifice GPS. In a block of L-band frequencies immediately adjacent to the block in which the civilian GPS service now operates (military GPS has additional satellite frequencies for its needs), the FCC has given LightSquared a waiver of Mobile Satellite Service (MSS) rules to permit "supplemental" terrestrial broadband data services to otherwise inaccessible locations. In fact, LightSquared proposes a system of over 40,000 transmitters, virtually identical in function to those already deployed by AT&T, Verizon and others for wireless service. The LightSquared licenses to construct and operate the system are conditioned on resolving interference problems with GPS. On the face of it, the MSS and GPS systems should be "compatible." They both would operate from comparable orbital space locations with comparable transmitted power levels. But the huge number of terrestrial MSS "repeaters" each operating at powers up to 1600 watts, change the game! Blockage of the received GPS signals through receiver overload from strong adjacent channel MSS terrestrial repeater transmissions becomes a huge risk! Even a Boy Scout working on a merit badge in "radio" should be able to see through this one! In just a decade GPS has come to be the underpinning for a number of essential, critical services. It has been widely successful. Why jeopardize it? "What must the FCC have been thinking?" The civilian GPS manufacturers and the military both strongly oppose the plan. Yet the FCC continues with it. [The utterly bizarre and high intricate politics behind this proposed system, which details are to byzantine to explore here, do explain much of the apparent illogicality. (hint: "think $$$")]. Next time, in the final installment of this series, we'll postulate how an engineering-competent FCC might approach spectrum management. What do you think? "Let's save the universe for RF!" The Old RF Curmudgeon Since 1963, LBA has been providing RF equipment and engineering consulting services for radio and television broadcast and wireless communications.
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