GPS Tracking ROI

Last time in this series we posted some recent examples of GPS jamming.  I wanted to really address the issue but my experience is limited to the practical aspects … I’m not an engineer, let alone a true scientist.  Also, some of my readers don’t care too much for the in-depth articles.

Better, then, that I crib off a man who has taught me tons about GPS, Richard langley … a real scientist, and one with a gift for explaining even deep technical concepts in the way that everyday users can gain valuable insights.  If you aren’t already a reader of GPS World, and Richard’s excellent "Innovations" columns I highly recommend them:

INNOVATION INSIGHTS with Richard Langley

Richard Langley

AS WE ALL KNOW, GPS SIGNALS ARE WEAK. At a receiver’s antenna, in the open air, their strength is about –160 dBW or 1 × 10^-16 watts. Compare this to a cell-phone signal, which might be –60 dBW or 1 × 10^-6 watts — 10 billion times stronger! While code correlation in the receiver lifts the GPS signals above the background noise floor, the signals are still relatively fragile, and building walls and other obstructions can significantly attenuate the received signal power so that they cannot be tracked by a conventional receiver.

It is the ratio of the signal power to the noise power per unit bandwidth that determines the trackability of the signal. Accordingly, if the receiver’s noise floor should increase sufficiently, even in an outdoor environment, the signals may also become untrackable. This can happen when the receiver is subjected to intentional or unintentional radio-frequency interference (RFI) by a transmitter operating on or near GPS frequencies. If the interference is strong enough, it can jam the receiver. Although intentional jamming is typically of concern only to military GPS users, unintentional jamming can occur anywhere and anytime and can affect large numbers of users within the range of the jamming transmitter. The jamming incident in San Diego harbor in January 2007, for example, affected all GPS users within a range of about 15 kilometers including a medical services paging network.

Such jamming renders a GPS receiver inoperable. But how do users know that their receivers are being jammed and not suffering some other type of malfunction? Clearly it would be advantageous for users to receive a heads-up when jamming signals are present and, if possible, for the receiver to take corrective action automatically.

In this month’s column, we look at some simple techniques, which can be easily incorporated into the design of a GNSS receiver, to detect, characterize, and actually mitigate RFI. Such receiver enhancements will benefit civilian and military users alike…. read the rest of Richard’s very useful column here.

… "Here’s yet another way to measure the success of GPS: by the efforts to negate it. While unintentional jamming continues to rise, intentional jamming by both foreign military forces and at-home miscreants of various stripes has shown increased vigor in the past six months. Related here are recent instances of intentional jamming on each side of the border, and (briefly outlined) one initiative mounted by the National Geospatial Intelligence Agency (NGA) to counteract it. Also, here are some ways to detect and prevent jamming." …

Got going on this issue as prompted by the above thread on Slash Dot.  There are a lot of goofy folk on /. with no more understanding of the GPS than what they see in movies … which is usually laughable inaccurate … Hollywood has very little clue.

But some /.’ers’ are very well versed and do their best to try to keep the liberal arts major who are still surfing from daddy’s basement at age 30 in line.

The first link above points to what may be a overly comprehensive article for many of my subscribers … but here’s a synopsis of interest:

The Domestic Variety

Meanwhile, several Internet sites offer small, localized GPS jammers for sale in the U.S. domestic market. These include a "GPS Blocker" with an advertised 10-meter to 20-meter range for roughly $200. "Just plug into a standard cigarette lighter with 12 V for power," says the web page, "and it will automatically protect you from any GPS tracking on and within your vehicle. This is a popular item with sales personnel and delivery drivers, who wish to take lunch or make a personal stop outside of their territory or route."

On May 28, the Federal Communications Commission (FCC) issued a citation to David Steele Enterprises of Newport Beach, Calif., for marketing in the United States unauthorized radio frequency devices in violation of the Communications Act of 1934, specifically a GPS jammer imported – ironically – from Taiwan. The company admitted selling 67 GPS Jammers between December. 5, 2007, and May 16, 2008. The FCC stated that the main purpose of the jammer device – blocking or interfering with radio communications – is clearly prohibited, and threatened fines of up to $11,000 per device sold.

Hacker sites also publish instructions for a "do-it-yourself GPS jammer that can have a range of up to several hundred feet. Keep in mind this is not an easy hack; a bachelor’s in electrical engineering seems like a prerequisite." The parts can be obtained at shopping-mall electronics retailers.  read the full article on GPS World.

So, the bottom line is, it certainly can be done.  If it is worth risking a Federal crime to take an over-long lunch break is still a question.  One thing for certain that the larceny-minded workers and other clandestine jamming enthusiasts might want to take into account … although you can jam the GPS signals, say for a single vehicle … it’s a very electrically noticeable even and the results may cause a lot more grief than just following the rules might have in the first place.,