From Mirrorbow Technologies Ltd
PlaneGadget Radar USB ADS-B Receiver   MarineGadget Radar USB AIS receiver
About ADS-B
PlanePlotter Software
Buy Now Accessories ADS-B FAQ   About AIS Software Options
Buy Now
AIS Accessories AIS FAQ

 

Frequently Asked Questions and Applications Information

 

Your product is so much cheaper than the others on the market, is it as good?
Yes. We felt that the current price of ads-b receivers was prohibitive for many enthusiasts so we deliberately set out to ensure the price was substantially more affordable than the existing receivers on the market by:

The receiver specification

· ADS-B (Automatic Dependent Surveillance Broadcast) Receiver
· USB 2.0 connection
· Powered over USB 5V
· Plotting and message decoding by PlanePlotterLite
· · · (a version of PlanePlotter that does not include networking)
· Antenna Connection – SMA Female 50 Ohm (Male on antenna)
· Antenna Included – magnetic base indoor whip antenna
· Range
· · · Practical range with antenna included (placed on 1st floor window sill) 110Nm
· · · Maximum range observed from hill top 210Nm
· · · Theoretical range 240Nm
· Plotting Software – PlanePlotterLite* included, full version supported (requires upgrade)
· ADS-B messages supported
· · · DF17 (sub types 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,29)
· · · DF0,DF4,DF5,DF11,DF16,DF20 (partial), DF21 (Partial)
· PlanePlotter approved for mlat ground station (you need the full version of PlanePlotter for this feature)
· CE marking, tested and conforming to the requirements for sale within the EU

What aircraft can the receiver pick up?
The aircraft needs to have on board ADS-B equipment to plot the position of an aircraft. This is standard on most commerical flights and some private flights. So mostly you will see airliners within the range of the receiver. Military aircraft use a different system so usually you will not be able to see the position of these. Often smaller aircraft and some military transmit more limited information, so you might get the flight name and aircraft ICAO number for those but no postion.

What kind of information can you see from an ADS-B equipped aircraft
Usually you will see the position plotted on a map, speed, height, aircraft unique ICAO number, flight number, rate of ascent/decent and heading.

What is the range of the receiver ?
Well other receiver manufacturers quote a theoretical range of 250miles, though in practice you would need a large antenna in a very high position for this. With the standard antenna supplied with the product placed on a 1st floor window sill you can get a range up to 100nM or so. This is based on actual observations from the supplied antenna placed on top of a biscuit tin (important). Thick walls through the house will much reduce the range, perhaps down to 20Nm for example though thick brick walls, but it is very dependent on antenna position. See Applications Information for more.

What is the sensitivity of the receiver?
We have elected not to quote a sensitivity as we feel this figure is misleading. Even in an AM radio receiver this figure can be manipulated and not just by changing the bandwidth of the front end. In an ADS-B receiver the actual sensitivity is influenced not just on the noise figure and bandwidth of the RF front end but also on the ability to demodulate and decode this information, and outside interference.
This is why we quote a practical range with the supplied antenna on a 1st floor window sill.

Does it support mlat?
Yes, the PGR from version 2.2 onwards is fully approved as an mlat ground station. Remember you need a full version of PlanePlotter for this feature as well as an internet connection and enough mlat enabled receivers in your area to get a fix. Please see www.planeplotter.com for more information on this.

What is the difference between PlanePlotter Lite supplied with the receiver and the full version available from PlanePlotter* as a €25(+VAT) Euro upgrade?
PlanePlotterLite* which is bundled with the PlaneGadget Radar receiver is supplied by COAA (it is not a RadarGadget product). The Lite version does not have networking functionality that allows you to share information with other PlanePlotter* users. You can upgrade by going directly to the PlanePlotter site here, you can get the full version.

Can I write my own software for this receiver?
The PlaneGadget-radar outputs undecoded data packets over a virtual serial port. More information about the format of this data is available in the Advance User Guide provided on your cd or available on request.

Linux and open source project - Jag here has open sourced his software to read the raw data output of the PGR http://adsb-pgr.googlecode.com/

 

PlaneGadget Radar - Applications Information

Quick Links:
Antenna Positioning
Using a different antenna or extending the coaxial lead

Antenna Positioning

The antenna has a magnetic base and is intended for placing on a metallic surface. An increase in performance is obtained by doing this, and typically this is achieved by simply placing the antenna in the centre of an upturned biscuit tin or biscuit tin lid. Any flat metallic surface which the magnetic base can adhere to is suitable.

The antenna is not weather proof and should not be placed outside. With the exception of temporary attended operation, for example on a car body (place something under the antenna to avoid scratching your car paintwork if you do this, like thin polythene).

As ADS-B transmissions are what is known as "line of sight" you need to place the antenna in a suitable position where it has a clear view of the sky. An upstairs window sill for example is a typical convenient position, where the view directly out of the window is clear of obstacles such as hills or adjacent buildings. However in this position you will see a clear pattern where aircraft on the other side of your house are either not seen or where the range of detection is lower.

The following picture shows PlanePlotter* with the receiving antenna is placed in a 1st floor window facing south east from Oxford. You can clearly see that range is up to 110miles or so in that direction, but limited to around 30Nm in the north west. The north west is blocked by being the other side of the building from the antenna, several walls of the building and the roof.

 

Using a different antenna or extending the coaxial lead

The receiver comes with factory preset gain to the optimum settings for the antenna provided. For most uses this antenna is perfectly adequate, and it is position thats most important.

We would not recommend using a different antenna for this product. In some cases using a larger antenna can result in a much worse performance than using the antenna supplied.

Rather than extending the coaxial lead we would recommend using a longer USB cable and perhaps USB hubs to extend the distance. This will minimise the losses of the more sensitive ADS-B signals.

 

NOTE: Whip antennas have a beam shape that is like a donut (imagine a donut laying flat with the antenna vertical in the middle). This means that there is a dead area on top of the antenna as it is vertically polarised. Often higher gain whip antennas have a more pronounced dip. Since the aircraft also has a vertically polarised antenna, when they fly directly overhead the signal can get substantially weaker, as both antennas are effectively pointing their tips at each other. This may cause aircraft to be lost when they are directly overhead, especially if you were tracking an aircraft through the roof material of your house for example which would already have attenuated the signal. It's counter intuitive that you might have more trouble picking up an aircraft overhead than 100 miles out, however with whip antennas the maximum gain is sideways, so the efficiency of the antenna close over head is much less than side on. You could find for example that aircraft over a few thousand feet within 2 miles become more difficult to detect.

*PlanePlotterLite is supplied by COAA an independent company separate from RadarGadgets and Mirrorbow Technologies Ltd.