Frequently asked questions

Q. How does it work?

A.

Q.  I am using the same usb tuner with SDR Touch Android app on the same phone (Samsung Galaxy S3 and now nothing works.

A.  With the SDR touch installed the driver doesn’t recognize the device. Try installing the apps one at a time. Attempt to use each one without the other installed.

Q. How do I install from the website

A. Download the file to the tablet then Enable Unknown Sources. Before attempting a manual installation of apps using the .apk files, you must first allow your phone to install from “Unknown Sources” (i.e. non-Market apps).

To do this, navigate to Menu -> Settings -> Applications and check the box marked “Unknown Sources“

Select the .apk file then install from sdcard using the built in installer.

Q. I have an DVB-T device with an Elonics E4000 with a tuner device and now nothing works.

A. The app only suporrts the RTL2832U tuners.

Q.What is ADS-B, FIS-B, and TIS-B , and UAT

A. If you are Choosing a Traffic System here are ADS-B Acronyms You Should Know
• ADS-B (“A, D, S, B”)
• Automatic Dependent Surveillance – Broadcast
• ADS-R (“A, D, S, R”)
• Automatic Dependent Surveillance – Rebroadcast
• TIS-B (“Tizz B”)
• Traffic Information Service – Advisory Broadcast (Not Mode-S TIS)
• FIS-B (“Fizz B”)
• Fight Information Service – Broadcast (Free Weather)
• CDTI (“C, D, T, I”)
• Cockpit Display of Traffic Information (MFD)
• 1090ES (“Ten-Ninety Eee Ess”)
• Extended Squitter Mode S Transponder (1090MHz ADS-B Datalink)
• UAT (“U.A.T.”)
• Universal Access Transceiver (978MHz ADS-B datalink)

For More info see ADS-B overview ADS-B-Overview4-26-13

Q.What does the mode s reply waveform look like?

 

 

 

mode_s_reply_waveform

 

 

 

 

 

 

 

Q.What does the FIS-B  waveform look like?

A. Modulation Rate

The nominal modulation rate is 1.041667 megabits per second.
Notes:
1. Each bit period = 0.96 microseconds.
2. Ground Uplink Messages will use the same modulation type.
3. Adherence to this rate is assured as part of the requirement of §2.2.2.4.

Modulation Type
Data shall be modulated onto the carrier using binary Continuous Phase Frequency Shift
Keying. The modulation index, h, shall be 0.6; this implies that if the data rate is Rb,
then the nominal frequency separation between ―mark‖ (binary 1) and ―space‖ (binary 0)
is f = h Rb. A binary 1 shall be indicated by a shift up in frequency from the nominal
carrier frequency of f/2 (+312.5 kHz) and a binary 0 by a shift of – f/2 (-312.5 kHz).
These frequency deviations apply at the optimum sampling points for the bit interval.
Notes:
1. Filtration of the transmitted signal (at base band and/or after frequency modulation),
will be required to meet the spectral containment requirement of §2.2.2.6. This
filtration will cause the deviation to exceed these values at points other than the
optimum sampling points.
2. The optimum sampling point of a received bit stream is at the nominal center of each
bit period, when the frequency deviation is either plus or minus 312.5 kHz.
3. Due to filtering of the transmitted signal, the received frequency offset varies
continuously between the nominal values of 312.5 kHz (and beyond), and the
optimal sampling point may not be easily identified. This point can be defined in
terms of the so-called ―eye diagram‖ of the received signal. The eye diagram is a
superposition of samples of the post-detection waveform shifted by multiples of the
bit period (0.96 microseconds). The optimum sampling point is the point during the
bit period at which the opening of the eye diagram (i.e., the minimum separation
between positive and negative frequency offsets at very high signal-to-noise ratios) is
maximized.

What is the source of the information received?

The FAA’s network of ADS-B ground stations is the source of the weather and traffic data received.

Is there coverage in my region?

ADS-B has excellent coverage in most of the US above 1500 ft. AGL. See the map below for complete details.

ADS-B Coverage Map

  • Black dots indicate approximate tower locations.
  • In areas that are blue, Android ADS-B should function well with only its built-in internal antenna at 1500 feet AGL and higher.
  • In areas that border the blue regions Android ADS-B should function well with the addition of its available external antenna.
  • In areas that are gray, the Android ADS-B will likely not function well at present. However, reception improves at higher altitudes.
  • List of UAT Ground Towers

At what altitude will I receive weather data?

The altitude Android ADS-B begins to receive weather will vary depending on the number of nearby towers, terrain and the obstacles that may be between Android ADS-B app and a tower – it is line of sight. This can be on the ground at airports where an ADS-B station is on the airport, but in general, Android ADS-B will start receiving weather between 500 and 1500 ft. AGL.

Are there any subscription fees associated with ADS-B weather?

No, there are no subscription fees and no registration required.

What weather products are available?

The Android ADS-B receives: NEXRAD radar, METARs, TAFs, TFRs, SIGMETs, AIRMETs, NOTAMs, Pilot Reports and wind/temperature aloft.

 

Does this satisfy the 2020 ADS-B Out requirement?

No. This is an ADS-B In only product. You will still need to modify your transponder or buy an ADS-B Out transmitter by 2020 to meet the upcoming FAA requirements if you plan to fly in airspace that requires a transponder today.

 

What is the range of ADS-B weather products? How far out do I see weather?

See AIM 7-1-11

Nexrad composite reflectivity (low resolution) Contiguous US
Nexrad composite reflectivity (medium resolution) 250nm
AIRMETs 100nm (airport surface); 500nm (en route/terminal)
SIGMETs and Convective SIGMENT 100nm (airport surface); 500nm (en route/terminal)
METARs 100nm (airport surface); 500nm (en route/terminal)
NOTAM (D) and FDC NOTAM (including TFR) 100nm
PIREPs No airport surface; 500nm (en route/terminal)
Special Use Airspace No airport surface; 500nm (en route/terminal)
TAF 100nm (airport surface); 500nm (en route/terminal)
Winds/temps aloft 1000nm

How often is the weather updated?

See AIM 7-1-11 (transmission interval)

NEXRAD composite reflectivity (entire US) 15 minutes
NEXRAD composite reflectivity (250nm regional) 2.5 minutes
AIRMETs 5 minutes
SIGMETs and Convective SIGMETs 5 minutes
METARs 5 minutes
NOTAM (D) and FDC NOTAM (including TFR) 10 minutes
PIREPs 10 minutes
Special Use Airspace 10 minutes
TAF 10 minutes
Winds/temps aloft 10 minutes

Are there different types of ADS-B ground stations?

Yes, although in practice it doesn’t really matter. You will usually receive many stations of all different types.

STATION TYPE RANGE WEATHER PRODUCTS AVAILABLE
Low-altitude 500nm Winds/Temps aloft
250nm METARs/TAFs/AIRMET/SIGMET/PIREP/SUA
150nm regional NEXRAD
100nm NOTAM (no CONUS NEXRAD)
Medium-altitude Continental US national NEXRAD
750 nm Winds/temps aloft
375nm METAR/TAF/AIRMET/SIGMET/PIREP/SUA
200nm regional NEXRAD
100nm NOTAM
High-altitude Continental US national NEXRAD
1000 nm Winds/temps aloft
375nm METAR/TAF/AIRMET/SIGMET/PIREP/SUA
all 158 Class B/C airports METAR/TAF
500nm AIRMET/SIGMET/PIREP/SUA
250nm regional NEXRAD
100nm NOTAM

How does ADS-B traffic work?

The most important thing to understand is that ADS-B traffic is not like ADS-B weather. The weather product (technically FIS-B) is broadcast to anyone with a receiver – like an AM radio station. The only real limitation is that you must be in range of an ADS-B ground station. This is what some people call a “dumb transmission,” because you simply turn on the receiver and start receiving radar, METARs and TFRs. No additional equipment is required.

ADS-B traffic (called TIS-B), on the other hand, is very different – it is not broadcast to anyone and everyone. Instead, it is a “smart transmission,” meaning the ADS-B ground station sends a customized data package to a specific aircraft, and only in reply to an interrogation from specific types of panel-mount avionics (ADS-B Out transponders like the Garmin GDL 88, Android ADS-B App ESG, etc.). If you don’t have the right panel avionics – and most airplanes today do not – you probably won’t get reliable traffic.

More Details

An aircraft that is equipped with ADS-B Out and squawking ADS-B will cause the FAA to send out a customized traffic product that is 30 nautical miles in diameter around the aircraft and 3,500 above and 3,500 feet below it. It is sometimes referred to as the “hockey puck” for obvious reasons:

ADSB Traffic Diagram

Let’s look at an example where you are in an aircraft that is not equipped with ADS-B Out, but your aircraft happens to be flying close to another aircraft that is (you are inside the hockey puck.) You can “listen in” on the ADS-B Out airplane’s traffic signal, and get a good display of traffic. But if you are close to the edge of the hockey puck, you may only see traffic on one side of you – remember, the 30 mile traffic display is based on the ADS-B Out airplane, not you.

Single Band vs. Dual Band

It’s also possible to see other aircraft air-to-air, meaning your Android ADS-B receives ADS-B Out transmissions directly from other aircraft. In this scenario, there is no need for a ground station, but the other aircraft has to be one of the very few equipped with ADS-B Out. Aircraft equipped with ADS-B Out can transmit on one of two frequencies: 978MHz and 1090MHz. Android ADS-B either receives 978, which includes ground stations and 978 air-to-air targets. Alternately  1090 can be selected, to receive all ADS-B Out aircraft air-to-air.

If you have ADS-B Out in your panel, you will be receiving a high quality traffic picture from the ground stations, so this air-to-air reception is less important.

Is TIS-B the same as Mode S Traffic?

No. Mode S traffic (sometimes called TIS-A) was popular in the early 2000s, with products like the Garmin GTX 330. This transponder received traffic information from terminal radar approach control, transmitted via Mode S. But the only traffic you receive with Mode S is the traffic in your local TRACON coverage area, and you only receive this information when you’re close to the TRACON. In addition, not all TRACONs support Mode S traffic.

TIS-B, on the other hand, does not depend on a TRACON. You see all traffic, even from en route radar facilities and TRACONs that do not support Mode S. In addition, the data is transmitted via ADS-B ground stations, not local TRACONs, so it is available over a much larger area of the country.

Bottom Line

There’s no doubt this subject is complicated. Here’s the one thing that is easy to remember: if you do not have ADS-B Out installed in your panel, you will not get reliable traffic on your iPad. That doesn’t mean it’s worthless, just incomplete. Most often, you’ll see lots of air-to-air ADS-B traffic, which is usually airline and cargo jets. Use ADS-B traffic as supplemental information, but never as a replacement for a good visual scan.

Read this article for more information, including a helpful graphic.

What about portable ADS-B Out products?

ADS-B Out transponders must be certified and installed in the panel .