Squawk Code Instability

Issues that can be seen with squawk code instability

Shadowing

• ATC may complain about seeing two targets with different squawk codes

Squawk codes picked up from other aircraft

• When passing close by another aircraft the squawk can be picked up and re-broadcasted on the aircraft with the tailBeacon or skyBeacon. 

Incorrect squawk code being sent 

• Altitude instead of squawk
• Emergency squawks being sent
• Any other squawk being sent other than the one being squawk on transponder

Why is can this happen?
skyBeacon utilizes uAvionix’s Power Transcoder to ensure proper synchronization of data elements between Secondary Surveillance Radar (SSR) replies and ADS-B transmissions. 

This synchronization is set up with the Monitor Threshold in the app. If this is not correctly set up, then the transcoder can either become over sensitive and pick up incorrect data that has been placed on the power wire or the sensitivity can be set too high and the squawk won’t be applied which leads to all 0000s being transmitted and ATC seeing two squawk codes. 

The uAvionix’s Power Transcoder works similarly to a squelch on a radio. Too sensitive and you hear lots of noise, not sensitive enough and you can’t hear anything said. 

Troubleshooting Steps:

tailBeacon / skyBeacon Software Update

10.15.2020 tailBeacon and skyBeacon software 1.5.1 software was released.

Description:

tailBeacon ADS-B Software v1.5.1 implements the following changes:

• Flight Plan ID (squawk code) is now reported as ‘0000’ instead of ‘Not Available’, prior to the tailBeacon Transponder Monitor detecting a squawk code. This situation can occur in non-radar environments, or prior to achieving radar contact.  The change is in accordance with updated TSO deviations as approved for tailBeacon, to better integrate with the operational characteristics of FAA Air traffic control (ATC) systems.
• Flight Plan ID (squawk code) data lifetime (timeout) has been updated from 60 seconds to infinity (through a given power cycle), which persists the last known squawk code after leaving a radar environment. The change is in accordance with updated TSO deviations as approved for tailBeacon, to better integrate with the operational characteristics of FAA Air Traffic Control (ATC) systems.
• The ADS-B firmware part number is now made available through electronic marking, viewable in the iOS and Android apps, as well as the Windows firmware update tool.

Compliance:

This Service Bulletin is mandatory.

*There are still customers that have not complied with the mandatory Service Bulletin.