One of my receivers uses a FlightAware 5.5dB antenna and a 10m length of CO100AF cable going to a Nooelec NESDR Mini 2 SDR stick. No amplifier is used. The cable losses are on the order of 3.2-3.6dB over the 10m length. The location is about 1000m above sea level. The antenna is mounted to a mast on top of a 15m observatory tower and, barring some mountains to the south, has a clear line of sight in all directions.
I recently received several Pro Sticks and want to experiment with them. My thought is using an N-to-SMA adapter on the antenna and hanging the FA filter and Pro Stick directly off the bottom of the antenna (the adapter, filter, and Pro stick would be in a small, weatherproof housing) to minimize losses. Iād then use a 10m-long active USB extender cable to connect down to the Pi. Most of the cable would be reasonably shielded from the elements, but thereād be maybe 1-2 meters that would be exposed to sun, rain, snow, etc.
Are there active USB extender cables that are designed for outdoor use and have, for example, UV-resistant cable jackets? If not, how best should I go about making a regular one more resistant? Wrapping it in electrical tape or self-amalgamating table is possible, but also tedious.
I was thinking of using heat-shrink tubing, but itād need to be large to get over the plugs/socket at the ends of the cable, and so wouldnāt shrink enough to fit the cable tightly.
I think that hanging the amp directly under the antenna will be a good way to get water into the pro-stick since it will essentially gravity feed into the box if there is even a sliver of an opening for it to get thru. You could probably use something like a hood (think about something like a top of a CD case at the base of the antenna acting as an umbrella for the small box that the pro-stick is in) both super sealed should keep it pretty close to dry.
Another worry that I would have is the weight of the cable and pro-stick pulling on the SMA connection.
If you are mounting all of that in a weatherproof enclosure, why not put the Pi in there as well and feed it all with POE using flooded CAT5 cable to bring it down to your network.
Good call. Itād probably be better to use a small jumper cable and a drip loop rather than directly mounting the filter and stick to the antenna. Either way, gobs of RTV and cable glands would be used for sealing any entrances to the box (except a drain hole at the bottom to remove condensation).
Good thought. Itād be nice if the extenders had some sort of better power supply (e.g. a boost converter at the computer end, and a buck converter at the device end) that can help overcome cable losses.
Also a good idea. PoE injectors/splitters have come down in price since last I looked, so that is a feasible option.
My concern is temperature: the mast is located outside and exposed to direct sun. Itās also located in the foothills of the Swiss Alps, so it gets quite cold in winter. I didnāt want to expose the Pi to that sort of environment, so I keep it inside the observatory and out of the weather/heat/cold.
Iāll look into an enclosure that could hold the Pi, PoE splitter, filter, and Pro Stick while still providing weatherproofing. Do you think itād be necessary to get proper waterproof bulkhead ethernet pass-through adapters, or would it be reasonable to bring the ethernet cable up through a small hole in the bottom of the enclosure (suitably sealed with RTV) and plug it directly into the PoE injector inside the enclosure? The hold would be on the bottom, so gravity would work in my favor. Such pass-through adapters are handy, but also quite expensive.
Everything is put inside an IP67 sealed connection box, since i took the picture iāve completed with a pigtail between pro stick and filter, and mounted a proper cable seal for the antenna cable. I will also add an pressure equalising valve so i doānt end up with the whole box full of condensation water.
I think the Pi and the other equipment will help keep the temperature in the box above freezing point during the winter, and it will be mounted in shade of the sun. Iāll be monitoring the temperature in the box via a 1-wire sensor.
The Pi and rest of the equipment is powered by POE, i purchased a cheap kit from TP-Link:
Nice! Out of curiosity, what are the dimensions of that box? Where did you purchase it from?
Also, what size seals (ācable glandsā, as Iāve always heard them described) did you get that would, when open, fit over the RJ-45 plug while also closing up tight enough to seal against the cable jacket?
Iād be curious to hear your results in regards to temperature and long-term performance.
I second those questions. I am planning the same setup to put on a 30 ft tower. Only difference is I am looking to use an extension cord that has damaged ends that I can replace after running into the box and through my wall. I will use outdoor cat5e and put both wires in conduit.
I have a setup using outdoor, direct burial shielded cat5e cable. It is over kill but I wanted to just do it right once.
The cable runs from my basement, outside in conduit, up into the attic. It is 150ā or 50M long and powers my unit via a POE to USB power adapter.
The ācable glandsā specify the diameter of the cable that they support.
I have a selection of sizes to support the COAX(LMR400, 35ā run to the chimney), GPS antenna(for NTP clock) and Cat5 cable.
Make sure that the unit will be cool enough. The SOC chip can handle a lot of heat, however, it may throttle back and cause issues with running MLAT. Not sure how the dongles handle extreme heat.
I put my FA dongle in a metal case for a bit of RF shielding.
The case from the website below fits without modification rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/
This setup has been in the air, 55ā up on top of a flat roof, through several heavy thunderstorms, heavy rain, golfball or larger hailstorms, high winds and up to 90F+ weather for almost three months of typical spring South Texas weather.
As you can see, the final install is with the components ānakedā, as that gave a 6C temp drop in the box over having the covers on.
I agree with jon in that the box will stay plenty warm enough for winter. The vent I used doesnāt really give airflow through the box, but does allow it to ābreatheā. I may add another one to the lower part of the cover to allow a passthrough draft, but will then likely need to put a sort of splash shield on the inside just in case a spatter of water makes it through there in a high wind. Thatās the down side of allowing a draft through the box. Havenāt had any problems with it yet as is, though.
Box is this: BUD Industries NBF-32006 It is pretty compact and cheap at about $13
The box measures 130 x 220 x 95 mm, its a standard electric connection box that i bought from my local hardware store.
The cable gland for the ethernet cable is intended for cables of 13-18 mm diameter, but can be āovertightedā quite a bit to seal even thinner cables. Since itās mounted on whats going to be the ādown sideā of the box it really doesānt matter if itās not 100% tight. If it becomes a problem i just cut of the connector of the cable and mount a proper gland, and then crimp on a new Rj45 connector.
Another option, if you doānt have the proper crimping tools is to simply cut the connector and mount a small Rj45 wall outlet, or a keystone jack in the box.
