RF Shorts for August 15, 2014

On-board Propulsion for Cubesats

Cubesats would be more useful if they were launched with a propulsion system that could boost them to a higher orbit or even send then past Earth orbit. Debra Werner, in her article Cubesats Driving Big Developments in Small Propulsion Systems writes that “NASA is exploring a wide range of propulsion technologies to enable cubesats to change altitude, conduct proximity operations, disperse and form arrays, including cold gas, monopropellant, liquefied gas, solid rocket, Hall effect (a 6 kilowatt Hall-effect thruster, above) and electrospray thrusters.”

One of the problems cubesat builders have faced is that including on-board propulsion would disqualify them from piggybacking on government flights. Werner said some cubesat developers are obtaining waivers from these rules. Read Werner's article for a comparison of the different propulsion systems being planned and built for cubesats.

Report Says Verizon Will Deliver Cable TV Over 4G LTE Using Broadcast Spectrum

RBR.com reports Verizon planning to use 4G LTE for wireless TV. The article, by “amclynn”, says “The idea of streaming that amount data over already-jammed cellular networks seems far-fetched, but Verizon claims it’s not that far off. With two big tranches of wireless spectrum now held by TV broadcasters coming up for auction this year and next, wireless capacity is about to expand. But Verizon says it can achieve TV over wireless broadband without adding additional spectrum. And it’s not the only one that may try.”

Jim Barthold, in his article Report: Verizon will deliver cable TV over 4G LTE on fiercecable.com, writes that spokesman Jim Gerace told Radio and Television Business Report that “no one has a wireless network better positioned to do this than we do.”

While he's got the year wrong, I agree with Barthold's comment, “While Verizon maintains it can do video over wireless with its existing network, things will improve noticeably if the carrier gets a big share of broadcast spectrum being put up for auction later this year.”

Adding my own comments on this article, as I've said before including 600 MHz capability to smartphones won't be easy as the antennas will have to be larger or less efficient than the current antennas used for the 700 MHz and higher spectrum. This isn't as big an issue for reception, where short antennas can be tuned and low power, low noise amplifiers used to boost the signal. Transferring power to short antennas is more difficult and making up for the loss of efficiency takes more transmit power, reducing battery life and increasing heat. It makes sense for Verizon and wireless carriers to consider using the 600 MHz spectrum to deliver video services. It should be ideal for LTE broadcasting and cable pay services, just as it was for advertiser and community supported free over-the-air TV broadcasting.

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.