EMC is the abbreviation for Electro Magnetic Compatibility. It does describe the capability of electronic devices to co-exist in an electronic environment. In general one can distinguish between two interference phenomena:
Inside a glider, there is various electronic equipment, which can create unwanted electromagnetic noise on the one hand side, and equipment, which is very sensitive to interference on the other hand side. Especially the radio is subject to both, being disturbed by other electronic instrumentation (Computers, Cellphones, DC-DC-converters…) while listening, and creating very strong signals while transmitting. If we consider the unwanted emissions created by a device, there are two possible ways for emissions:
The closer the spearation of devices is, the more critical EMC issues are. In a narrow cockpit the need for well behaved equipment is obvious to ensure proper function of all devices in use. Therefore we tested the OpenVario for compliance to the most important EMC standards and present the results here.
The following freguency ranges are used in airborne equipment and need to be protected against unwanted disturbances:
Frequency Range in MHz | Service Description | Nominal Value | Measured | Remarks |
---|---|---|---|---|
117.975–137 | VHF AM Radio | dBµV/m | x | Very sensitive to disturbance due to AM https://en.wikipedia.org/wiki/Airband#Spectrum_usage |
320-340 | ILS | dBµV/m | x | Not really important for gliders… |
868 | FLARM | dBµV/m | x | RX case only |
1227.60 | L2GPS | dBµV/m | x | L2GPS https://en.wikipedia.org/wiki/GPS_signals#Frequencies_used_by_GPS |
1575.42 | L1GPS | dBµV/m | x | L1GPS |
960-1164 | GPS | dBµV/m | x | DO-160 |
1559-1610 | GPS | dBµV/m | x | DO-160 |
1610-1680 | GPS | dBµV/m | x | DO-160 |
5020-5100 | ? | dBµV/m | x | DO-160 |
There are many EMC-standards in general, but for civil aviation the most often applied standard is the RTCA/DO-160F. Further there is an important military standard called MIL STD 461F, although not applicable to the OpenVario, it gives valuable information about the EMC characteristics.
Coming soon…
Coming soon…