Category Archives: Wireless

Communications: California loses cell phone service in power cut offs

Up to 1,000 or so cell sites went off line due to the extended power shut down in northern California:

Even as California burns, the cell phones of many residents have gone mute, preventing them from giving or getting emergency information.

Source: Kincade Fire: Why you can’t make cell calls in this emergency

Most cell sites are configured with battery backups to keep running during short term outages but are unable to continue running without power for days. Some also have generators but due to the power shut down and wild land fires, they were unable to be serviced with additional fuel.

Some have thought that with communications becoming a commodity, we would no longer need distributed emergency communications from ham radio. Instead, the more communications we’ve built and the more it has been used, the larger the impact of its loss. Amateur Radio emergency communications remains a vitally important component of emergency planning and service delivery.

“5G” is mostly about adding capacity in major markets, and offering a broadband-like wireless connection

There had been much talk about 5G expanding rural coverage. Nope.

5G involves both new, faster modulation, but especially involves large spectrum allocations at millimeter wavelengths. The latter do not travel far due to path loss. This is why urban areas are expected to see small 5G base stations (or cells) on every block. (Some of the tech, albeit with less capacity, can be deployed at lower frequencies – existing cell frequencies below 1 Ghz and in the 1 to 6 Ghz range,  with somewhat greater range. But the big capacity improvement comes from the use of bands at 26 Ghz and higher.)

5G is primarily a way of delivering higher speed and greater capacity in urban markets, and provides a way to compete with wired Internet providers. That’s about it. Present technology also requires the installation of an outside antenna.

How much speed do you actually need? As the WSJ reported, few people come close to fully using a 100 Mbps connection – markets that are marketing faster speeds as supposedly needed for video are selling snake oil.

Source: 5G promises

Many #quadcopter #FPV television video transmitters are not legal #drones

Anyone who has looked anywhere online – Youtube videos or just perusing online stores for model aircraft parts – has seen devices for sending video signals from a model aircraft.

Most of the ones I see are not legal and do not comply with FCC rules in the U.S.

Many, if not most, of the devices that advertise “500mw” or “800mw” or “1200mw” and so on, are not legal devices, as used by most FPV flyers.

You have two options to legally add video or telemetry signals to your quadcopter.

  1. Use a Part 15 “unlicensed” device that complies with FCC rules. Up to 1 watt is permitted for spread spectrum (Wi-Fi) devices only; much lower limits apply to analog TV transmitters as used by many FPV video links.
  2. Use a device intended for use by a licensed Amateur Radio operator. When used for model aircraft control, FCC rules restrict the transmitter link to 1 watt (any mode including analog TV is fine).

Within Part 15 there are two classes of devices of interest:

  1. Spread spectrum, permitted up to a maximum of 1 watt power out.
  2. Non spread spectrum, which may be limited to as little as 1 milliwatt power out.

Part 15 Rules

The Federal Communications Commission (FCC) establishes rules for use of the radio spectrum.

Titled 47 Code of Federal Regulations, Part 15 specifies allowable limits for low power devices, unintentional and intentional RF emitters and other operations.

For a Part 15 (no licensed required) device, the 1 watt limit refers to spread spectrum devices like WiFi operating in specific bands allocated for Part 15 usage. Some quadcopters send video over WiFi and can legally transmit up to 1 watt. When the Tx is connected to a “gain” antenna, the power is to be reduced proportional to the antenna gain figure (about 1 db less power for each 1 db of antenna gain in excess of 6 db antenna gain).

Many of the FPV TV transmitters are running analog TV signals (not spread spectrum) and are restricted to vastly lower power limits. Most of the analog devices sold exceed legal limits. Some even operate outside the Part 15 bands, which is clearly against Federal rules. The FCC has proposed a $2.8 million fine to Hobby King for selling numerous devices that violate FCC rules and regulations.

Most Part 15 devices operate (like Wi-Fi) in the 2.4 Ghz band, or the 5 Ghz “Unlicensed National Information Infrastructure” bands. Some telemetry data devices used by model aircraft enthusiasts operate in the 902-928 Mhz Part 15 band.

433 Mhz

A frequency near 433 Mhz is allocated for low power unlicensed operations in Europe. This frequency is NOT LEGAL to use anywhere in the United States where it is allocated to the Amateur Radio Service. There are numerous devices on 433 Mhz now being sold in the U.S. for remote control functions that are not legal in the U.S.

Part 97 Amateur Radio

The second 1 watt power limit applies to Amateur Radio operators. If you have an amateur radio license you can legally run up to 1 watt (any mode of operation) specifically for the control of model aircraft. This is spelled out in FCC Part 97.215.

While ham radio operators may operate up to 1,500 w PEP, the actual wattage level depends on the license class, the band in use, the geographic location, and the purpose (97.215 limits power output for telecommand of model aircraft).

If you have a ham radio license you can run up to 1 watt for the purpose of remote control – without having to provide standard station identification and providing remote control of the transmitter (say to turn a video transmitter on the aircraft on and off remotely).

A amateur radio operator could run more than 1 watt for remote operations provided station identification is used and there is a way to control the transmitter remotely.

Amateur Radio operators have access to many radio bands that may be used for remote control links such as in the 420-450 Mhz band. The 902-928 and 2390-2450 have overlap with Part 15 bands (these bands are co-allocated to multiple radio services). Amateur radio operators also have access to 5650-5925 Mhz which partially overlaps with Part 15 allocations at 5150-5350 and 5470-5825 Ghz. Some (but not all) Part 15 5 Ghz devices might be able to be configured for use as Amateur Radio devices.

Summary

Most of the Wi-Fi devices are probably okay.

Many, may be most, of the analog TV transmitters violate FCC rules. There are tons of such devices advertised online.

If you have a ham radio license (I do), you can legally run these analog transmitters up to 1 watt. Thus you can purchase one of the “not legal Part 15” FPV transmitters and use it, if you have a ham radio license.

My interpretation is that hams can run more than 1 watt provided you use normal station callsign identification on the link and you can remotely control the transmitter on and off.

Hope that helps.

Britain may shut down plan to switch emergency service communications from radio to private 4G cellular network

Britain has been moving toward shutting down traditional radio communications systems and moving all emergency services to a private “4G Emergency Services Network”.

While much more expensive than their existing emergency radio system, it would at least be less reliable than what they have now. (Not a joke.)

They are also considering running both – radio system for voice and 4G for data (the first rule of government contracting is never do one when you can do two for twice the price!)

Source: Britain mulls ‘complete shutdown’ of 4G net for emergency services • The Register

AccuWeather app continues spying on user’s location #privacy

New tests reveal that while one privacy-invading feature was removed in an app update, the app still shares precise geolocation coordinates with advertisers.

Source: Despite privacy outrage, AccuWeather still shares precise location data with ad firms | ZDNet

This is done without the user’s consent.

Accuweather says it uses one’s location data to provide local weather forecasts but it appears the primary purpose is to optimize ad revenue. A side effect is that a dossier of our movement is constantly maintained by corporations.

With Android, if you use the GPS location features of the phone for any purpose what so ever, Google logs your location in the cloud. You cannot opt out of this – your choice is to use location services and be surveiled by Google, or not to use any GPS location features.

We now use an offline Garmin navigation product which presumably is not logging our location as it is only connected to the Internet a few times per year to update the software. But we really don’t know – may be Garmin is also logging our location albeit with a months long delay.

Astronomers propose global network of low cost receivers or cell phones #Astronomy #Radio

Astronomers have proposed a global network of radio receivers to search for fast radio bursts. Their concept would use either smart phones and an app listening to a portion of the cellular spectrum allocation, or a low cost device that could be plugged in to the USB port of personal computers.

Full paper available at the link.

Source: [1701.01475] Searching for giga-Jansky fast radio bursts from the Milky Way with a global array of low-cost radio receivers

University of Washington: upcoming Internet accessible lecture on #IoT #Wearables Technology

Next Thursday at UW CSE or view remotely:
http://www.cs.washington.edu/events/colloq_info

UNIVERSITY OF WASHINGTON
Computer Science and Engineering
COLLOQUIUM

SPEAKER:   David Kotz, Dartmouth College

TITLE:     Amulet: An Energy-Efficient, Multi-Application Wearable
Platform

DATE:      Thursday, December 1, 2016
TIME:      3:30pm
PLACE:     EEB-105
HOST:      Tadayoshi Kohno

ABSTRACT:
Wearable technology enables a range of exciting new applications in
health, commerce, and beyond. For many important applications, wearables
must have battery life measured in weeks or months, not hours and days as
in most current devices. Our vision of wearable platforms aims for long
battery life but with the flexibility and security to support multiple
applications. To achieve long battery life with a workload comprising apps
from multiple developers, these platforms must have robust mechanisms for
app isolation and developer tools for optimizing resource usage.

We introduce the Amulet Platform for constrained wearable devices, which
includes an ultra-low-power hardware architecture and a companion software
framework, including a highly efficient event-driven programming model,
low-power operating system, and developer tools for profiling
ultra-low-power applications at compile time. We present the design and
evaluation of our prototype Amulet hardware and software, and show how the
framework enables developers to write energy-efficient applications. Our
prototype has battery lifetime lasting weeks or even months, depending on
the application, and our interactive resource-profiling tool predicts
battery lifetime within 6-10% of the measured lifetime.

(Featured image: Seattle photo from University of Washington web site at http://www.washington.edu/about/)

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