Unmanned Vehicle Operator Info

Unmanned Stealth?
Small unmanned aircraft are naturally invisible to "Primary Radar," the part of ATC radar that locates targets from reflected pulses back to the radar dish antenna, aka "skin paint." It makes sense when you think about it. Most small UAVs are no larger than a Canadian Goose, so why would ATC be able to see your UAV?  While this stealth can be useful during covert military operations, more often it presents a problem for ATC controllers providing separation services, which is impossible when some of the aircraft (small UAVs) are invisible.

But if the small UAV has a transponder, it can be seen on "Secondary Radar" which receives the replies from XP transponders to locate the UAV.  This is why it is especially important that small unmanned aircraft carry XP Transponders.  Without a transponder, your UAV is an invisible hazard.  With a transponder, you integrate seamlessly into existing airspace systems,  and the small size-weight and power (SWAP) footprint of the XP series means you don't have to sacrifice fuel, duration, or mission payload to be compliant and "play well with others."


ATC Expectations, when  should I squawk?   

Transponders typcially have a four-position power switch to select operational states.  OFF, STBY, ON, and ALT. Although the XP series of transponders don't have a physical switch, we have created similar operational states with XP transpondres which correspond to these settings to fall into line with convetion.
 

OFF is self explanatory. 
 

 

In STBY, circuits within the transponder are powered so they can warm up. Older transponders required a warm up period, but the Sagetech XP series can be switched directly from OFF to ON or ALT with no warm-up period. 
 

 

ON The trasponder replies to interrogations with the 4-digit sqwawk code assigned by ATC. 
 

 

ALT, which is the normally selected position for 99% of flights, the transponder replies to ATC radar interrogations with both the 4-digit squawk code set in the transponder, as well as the present pressure altitude measured by the altimeter. This altitude can also be provided to the transponder over the serial contorl interface. 

A note about altitude is in order here. The altitude reported by the transponder must be a pressure altitude, what your altimeter would read with an altimeter setting of 29.92. GPS altitude should never be provided as the aircraft altitude, unless this is pre-coordinated with ATC. Altitude encoders have very specific accuracy requirements, which is not surprising when you consider the whole point is to keep planes from colliding. Sagetech includes a fully compliant altitude encoder in every XP transponder model to make altitude reporting a snap. Simply connect the pressure port on the XP transpodner to ther static-pressure port line or your aircraft pitot-static system.


What Code Should I Squak?
Squawk codes can be individually assigned, or "non-discrete" codes that are used by multiple aircraft according to how they are operating.  Examples of non-discrete codes are 1200 for general VFR traffic, 7700, the Emergency code, 4000 for military aircraft operating on Military Training Routes (MTRs) or Military Operations Areas (MOAs).  The easy answer is to call your local air traffic controlers, or the agency that "owns" the airspace.  They will provide you a sqawk code for your flight.

What do the Modes Mean?

Military modes are numbered whereas civil codes are letterd.  The codes that are relvant to XP use are listed below

Mode 3/A

Mode 3 (miliatary) and Mode A (civil) are one in the same.  They are the 4-digit squawk code assigned by ATC.  Numbers available for use in each position are 0-7. For example, ATC might say, "Swawk 4723"
 

Mode "C"

Mode C refers to pressure altitude reporting capability.
 

Mode "S"

Mode S provides a general datalink capability for ATC traffic managment.  A big benefit of Mode S is that aircraft can be selectively interrogated, greatly reducing frequency congestion, which is important in high-density terminal areas like Chicago and Frankfurt.

ADS-B
ADS-B is the next generation of ATC traffic location system, which is collectively referred to as NEXTGEN.  With the new system, aircraft will simply report their GPS position and altitude instead of using complicatd radar systems to locate aircraft.  ADS-B infrastructure is much cheaper to install because ground stations are simple radio transceivers rather than highly complex systems with spinning radar dish antennas.  Additinoally, the NEXTGEN system includes data broadcast services allowing pilots of properly equipped aircraft to receive weather forcasts, traffic reports and much more.  ADS-B Out referrs to the capaility of an aircraft to report its location and other data.  ADS-B In refers to the capability of an aircraft to receive data from other aircraft and ground stations. 

 

Under Pressure? Why you need our pressure altitude encoder?
The Sagetech XP transponders have an integrated altitude encoder, compliant  up to 50,000 feet, allowing Mode C altitude reporting.  All you have to do is connect the XP altitude encoder to your static pressure line of the aircraft pitot-static system.  It couldn't be easier to squawk Mode C with Sagetech transponders.



When does my aircraft need a transponder?
Transponders are required equipment for aircraft opertaing below 10,000 feet in any of the "Mode C Veils" surrounding large terminal areas as small as Portland, OR, and as large as Chicago. But even if you operate away from airspace which requires a transponder, you'll want to seriously consider equipping your UAV with an XP transponder becasue without a transponder your UAV is probably invisible to ATC radar (see "Unmanned Stealth" above). Increasingly, UAVs operating in specially designated airspace are being required to carry a transponder. And as rules are created to allow civil use of UAVs in the National Airspace System (NAS), we expect that UAVs sharing airspace with manned aircraft will be required to carry transponders and/or ADS-B out equipment. The XP series offers solutions in both areas.