RTL-SDR's in an outdoor box

Main forum to discuss RTL-SDR related topics.
Post Reply
fresnoboy
Posts: 2
Joined: Thu Jun 14, 2018 4:56 pm

RTL-SDR's in an outdoor box

Post by fresnoboy » Thu Jun 14, 2018 5:05 pm

Hi. I'm building a new house, and I have the opportunity to mount a few antennas on a horizontal mast on the roof (supported by a very nice heavy duty mast coming through the roof. I am a ham, so I will have a 2m/70cm vertical, a GMRS antenna, a 1090 MHz ADS-B antenna, and a couple discones and maybe some L band patches.

What I was thinking about doing to reduce the feedline length was having a weatherproofed box on the mast that the feedlines would terminate into and maybe have 4-5 RTL-SDR's right there plugged in to one or two powered USB hubs, and then have the USB cables go down into the attic where a NUC running ESXi sits running all the software.

I'd have to provide ventilation and cooling of course. Has anyone done something like this before? Anything I should watch out for?

thx
mike

aurgathor
Posts: 26
Joined: Wed Apr 25, 2018 8:14 am

Re: RTL-SDR's in an outdoor box

Post by aurgathor » Thu Jun 14, 2018 11:49 pm

USB 2.0 max cable length is a bit over 15 ft, so depending on the actual distance you may either need an extender cable, or one or more USB hubs. Since the RTL-SDR dongles can draw well over 300 mA, the last cables that connect to he dongles should be sized accordingly to avoid excessive voltage drop over them.

Do you want separate USB cables for each dongle, or you plan to connect them to a hub up there, and only one USB cable that goes into your computer?

fresnoboy
Posts: 2
Joined: Thu Jun 14, 2018 4:56 pm

Re: RTL-SDR's in an outdoor box

Post by fresnoboy » Fri Jun 15, 2018 3:26 pm

Thanks for the reply. Yes, I was planning on putting a powered hub up there, and then using USB over CAT5 extenders to go from the outdoor housing into the attic where the NUC will sit. That way I don't have to try and carry power for the sticks over the USB cable itself, just signal.

I'm trying to figure out how to vent the housing to keep things cool enough but keep critters from being able to get in there or water condensing etc...

The antennas (other than the L band patch) will have N connectors on them and will have LMR-400 patch cables to the box with internal N connectors, and then run N to SMA cables inside the box. It'll also pass through some of those antennas into the attic as well on more LMR400. I figure the RTL's won't be able to add noise to the other cables running through the box since they are all shielded.

thx
mike

aurgathor
Posts: 26
Joined: Wed Apr 25, 2018 8:14 am

Re: RTL-SDR's in an outdoor box

Post by aurgathor » Sat Jun 16, 2018 1:50 am

I have a couple of sets of USB over Cat5 extenders, and I found that their performance is very poor. They would barely work with my 50 ft Cat6 and weren't very reliable with 25ft long cables (Cat6 or Cat5) either. But other extenders using a different chipset may work better.

In any case, currently I'm just stacking USB hubs. USB over fiber optic would be nice (and would give inherent galvanic isolation), but they are kinda expensive.

You can leave the bottom of any box open and cover it with a bug screen -- that would allow more or less normal air circulation, but keep most would be visitors out.

Post Reply