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(Antenna Mounting Continued)
Ground antenna should be mounted with as much distance away from the ground as possible
This is to reduce ground reflection and has a considerable effect on reliability of an RF link
Antenna spacing should be minded
Any device with diversity (multiple antenna inputs) should have it’s antennas mounted with some spacing between them. Always follow manufacturer guidance here.
IE our VN-300 has specific manufacturer recommendations regarding recommended spacings and clearances
Different devices should have their antennas spaced out
See notes about frequencies and channels above.
Some notes about lightning
This entire section can be ignored for WARG purposes on nice days and the odds of a lightning strike are relatively low so don’t worry too much about these guidelines
As long as the current from a lightning strike is allowed to pass through your structure relatively unimpeded it will not harm the system
Notably isolating important electronics from the structure is important for this, see above.
To ensure this is possible having a somewhat conductive frame helps
This is not possible for composite frames and thus more complex techniques can be employed
Lightning likes to, if possible, enter and exit through sharp points
Ensuring that the sharpest points on a region of the system are all not electrical elements (notably antennas) will ensure lightning passes where we want it to!
A side safety note is that people are also relatively sharp points sticking out of the ground, however, unlike structures, you aren’t replaceable.
Be sure in lightning prone weather that people are not the path of lowest impedance for a lightning strike! This can be done easily by ensuring taller, pointier, grounded structures are nearby humans.
For ground equipment (towers and stations) grounding rods can be used
Notably this may not be possible for ecological reasons as well as if our ground station is on pavement
Grounding rods should connect into the earth (with a pointed end) electrically to the sharpest point at the peak of the structure
Ideally, as mentioned above, the entire structure is conductive which makes this easier to achieve.
General Gender Conventions
The gender for any connectors used on the drone is critical and should not be taken lightly. Each specific connector series may, in rare cases, deviate from this standard though a reason should be cited in architecture document where that connector is defined.
The following convention will be adopted: any electronic source’s output power will have a female connector and any electronic power consumer input power will have a male connector. In this case male refers to the connector with pin like electrical contacts and female as the connector with socket like electrical contacts.
When deciphering connector gender for the purpose of this standard be sure to ignore any plastic shrouding that may be present. Please note that some connector manufacturers have differing definitions of genders which should be ignore for the purpose of ensuring compliance with this standard.
This standard is critical for safety because we want sources which are always live to be hard to accidentally contact (i.e. short) accidentally whereas loads input power is totally safe to be shorted as there is no power source. This standard is adopted by the COTS world as well so for compatibility we keep this standard.
For non-power connectors, data connectors, please refer to the Pixhawk standard mentioned in another section.
For non-gendered power connectors (i.e. Anderson PP45 connectors) they are generally protected in sufficient shrouding and consequently this gender convention is not directly relevant.
Finally, some examples of this to avoid confusion. For examples of electronic source’s power output connectors we have: battery power connectors, ESC leads to the motor & buck/ldo/bec board output power. For examples of electronic load’s power input connectors we have: power distribution board input power, & ESC input power. Another system level super common example is when you want to plug something into the wall (~120VAC & ~60 Hz) (an electrical source) it has female electrical contacts and the thing you’re plugging in (an electrical load) has male contacts.
Compute
The Holybro PX_ system should be placed as close to the center of rotation of the drone as possible, offset in ONE axis only to allow for the installation of the VectorNav VN-300 module. There is an arrow on the top of the Pixhawk, which should point toward direction of forward flight. Keep in mind that wires need to be accessible from the “back” of the pixhawk (I/O & FMU Output banks), as well as from the side for USB debugging as well as retrieval of the SD Card.
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