SV-XPNDR-26X Installation, Configuration, and Testing
SkyView System Installation Guide - Revision K 11-15
currently always be set to SKYVIEW. See the Serial GPS Position Input section above for
additional details.
GPS STATUS: Displays whether the SV-XPNDR-26X is receiving valid GPS data.
Altitude Encoder Calibration
In most transponder systems, a calibration is normally carried out every 24 months, as part of
the altimeter checks on the aircraft. The maximum allowed difference between the primary
altimeter and the altitude encoder is 125 feet in ETSO C88a and TSO C88b. The primary
altimeter in SkyView and the altitude encoder are one and the same device. It is therefore
impossible for the encoder and the primary altimeter to exceed 125 feet of altitude difference.
They will always be exactly the same as each other, thereby meeting the TSO requirements.
Therefore, no altitude encoder calibration is possible or necessary.
At times it may be useful to know the altitude that is being reported to the transponder. Since
SkyView sends pressure altitude to the SV-XPNDR-26X, setting BARO to 29.92 will display the
pressure altitude being transmitted to the transponder in the normal SkyView altitude display
on the right side of the PFD page.
However, do note that there is a single point altitude adjustment, located in SETUP MENU >
HARDWARE CALIBRATION > ADAHRS CALIBRATION > ALTITUDE ADJUST that adjusts SkyView’s
barometric altimeter. This adjustment affects both the displayed altitude and the encoded
altitude that is sent to other devices.
Post Installation Checks
Post installation checks should be carried out in accordance with your certification
requirements. These checks should include:
Mode S interrogations to verify correct address programming.
Verification of the reported altitude using a static tester.
Where installed, verification of correct squat switch ground/airborne indications. In an
aircraft with a squat switch, setting the Mode switch to ALT when the aircraft is on the
ground should leave the transponder in GND mode; when the aircraft becomes
airborne, the mode should switch automatically to ALT.
Interrogations to verify the receiver sensitivity. A Mode S transponder should have a
minimum triggering level (MTL) of between -77 dBm and -71 dBm. Failure to meet this
requirement usually indicates antenna or coaxial cable problems.
Interrogations to verify the transmitted power. A Class 1 installation should have no less
than 125 Watts at the antenna (and no more than 500 Watts). A Class 2 installation
should have no less than 71 Watts at the antenna (and no more than 500 Watts).
Failure to meet this requirement is also generally due to antenna or wiring issues.
Where installed, verification of the GPS position source and ADS-B outputs. Whenever a
valid position is received by the transponder and the transponder is in any mode other
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