PoE for RPi - any one using + Attic better than window?

Morning all,

MY set up is currently in my second floor office - with a wire colinear antenna in front of a double glazed window. Works, quite well, but strongest in line-of-site through the window (unsurprisingly).

Until I can get this roof mounted, I’m thinking of moving the Rpi and the antenna to the attic, running off PoE, to keep the coax run down.

So, couple of questions:

  1. Would you agree that attic mounted vs window mounted antenna is better?

  2. PoE - all the PoE splitters I’ve seen terminate in a 2.1mm “barrel” for the power connector (in / out) . Of course the RPi uses a micro usb connection.

If anyone else here has used PoE (which I’m sure you have) , how did you connect the RPi to the power “fork” on the PoE splitter?


Ooops, sorry people - see this has been answered in a flurry of responses to my earlier post!

Basic consensus seems to be:

PoE is too noisy / doesnt offer enough power

Attic / roof tiles block a lot of signal

Shame, 'cos that what I was hoping to do - in the belief it would be better than through my office window.

Still open to other opinions or thoughts…

I have one in the attic and one on a pole above the roof line. Another is mounted below the roof line pointing West. These are my daily median results over the last week:

flights positions aerial
1,546 76,849 attic
1,882 72,307 pole 11m agl
1,412 60,759 mag mount facing West

I did have one indoors in the window but the results were very poor.
The installation in the attic is an old laptop running dump1090 and Planeplotter connected to the LAN by PLT plugs to router downstairs.

I thought I’d answered this already elsewhere

5V POE with a decent length of CAT5 cable, you don’t get enough volts the far end to run the Pi.

So do the POE at a higher voltage and put a power regulator by the Pi ebay.co.uk/itm/151346691650 (or you could get a car cigarette lighter USB charger and pull the circuit board out of it))

The regulator runs cool - so is not lossy.

If the Pi requires 0.5a and you put 15v up the line - then you will only send 1/3rd of 0.5A up the wire.

if at 5v you lost 1v you will only lose 0.33v on the POE (Ohms law!), and the regulator will still be happy.

(numbers used are for the convenience of doing the calculations)

15v also happens to be sufficient to run an aerial amplifier later.

@PeterHR, you did - sorry mate, by the time I posted this, I saw you’d replied to the other thread!

The glass in many windows is a good attenuator - it may degrade 1 GHz and above signals significantly.

An attic may be better for an antenna - but it depends a LOT on possible insulation materials. Anything foil backed may also attenuate signals as well. Same goes for insulation / siding on a building.

You can help overcome some of this attenuation by having a better antenna (higher gain - not necessarily so easy to construct) as well as ensuring the connection between the antenna and receiver has the shortest run possible of lowest loss coax.

Raspberry Pi’s can suffer from overheating - if you put it in an attic that exceeds 40C / 100F the ambient heat combined with the heat generated by the Pi may lessen its life / cause intermittent problems.

  • W1QA

See my situation here:



Afternoon all,

After having the usual pain of crimping RJ45 plugs over the weekend, I finally gave up on the “very long patch lead” idea, and moved to the wall patch - which worked first time…

I now have wired net access to the attic, with a standard 1.5m patch lead either end (to router / RPi).

The original idea was to run PoE over the original “long patch cable”.

Question is - is PoE likely to work through the wall port?

(I know it’s largely a case of “try it and see”, but thought I’d see if anyone here had any experience, I know quite a few of you on here have had a look at PoE for exactly the same purpose.)

I don’t know what you mean by “wall patch.” If you mean Ethernet over AC power line adapters, no, PoE will not work. If you’re talking about a 4-pair cable in the wall with RJ-45 jacks at both ends, then PoE will probably work. For an inexpensive way to get there look at the TP-Link TL-POE200, around $25 for the full setup including wall wart, injector, splitter, and some cables.

bob k6rtm

Standard RJ45 socket in the attic space?
Matching socket down below?

If doing that sort of installation - you could have also run a power cord at the same time.

This is similar to the way commercial installations are done - POE will work, if it doesn’t - there is an error in the cable / socket installation.

@PeterHR, @Bob,

Thanks Gents - yes, that’s what I’m thinking of… (Yes, PeterHR, that’s my set up).

Made the initial “test” move last night.

With a great deal of thanks due to Mr.Gaffa and Mr.Tape, my antenna and RPi are now in the attic, running off an extension lead from the bedroom below.

Initial indications are good - VRS shows c140nm range in both NW/SE directions, with lesser ranges at other points.
Running since c18:00 last night, so will compare to last Tuesday once today is complete.

Current (flawed) calculations suggest 2,249 air craft based on basic Reports → Aircraft %'s from last week. (vs 1524 last week). I dont expect to hit this number, but certainly indicates some level of improvement.

If this remains as good a change as appears, I’ll crack on and get the PoE stuff next week.

Still running on c15ft 75 Ohm coax (which I dont need) but have left for comparison.

Will cut down to min run after one week of reports to test.

Both my PiAware setups use 802.3af 48v PoE via a device like this:http://www.tp-link.com/en/products/details/?model=TL-POE10R. It takes the ethernet+poe and spits out 5v to my Pi/Pi2.

I have the Pi, USB stick, and PoE splitter in a plastic weatherproof box attached to the side of the building, just below my antenna.

FA Site 5656:
Hardware: dropbox.com/s/3q3hy79z2zraj … 8.jpg?dl=0
Range: dropbox.com/s/m4nn7lmmh6xt8 … 3.jpg?dl=0 (there’s an apartment block directly to my west)

That looks like the exact same one that I was using. “Hardest” part was getting the microusb cable cut and soldering on a coaxial plug for power.

More info here: http://discussions.flightaware.com/ads-b-flight-tracking-f21/new-antenna-results-t19582.html

eta: yes, I realize in those pictures the Pi is powered via USB hub, but I found that to be somewhat unreliable and had issues with the Pi, so I ended up bypassing it and plugging the Pi directly into the PoE converter, which resolved a few of the issues. I have since completely removed this set up and have the dongle plugged into my virtual server and connected to a Ubuntu server for processing.

Yeah my original Pi-b is powered via USB hub, as I had trouble getting it to supply enough power to the USB stick. My second one is a Pi2 and there is no USB hub in the box. I cut the end of a USB cable and connected the USB power wires to this: http://jaycar.co.nz/Interconnect/Plugs%2C-Sockets-%26-Adaptors/DC-Power/2-1mm-DC-Plug-with-Screw-Terminals/p/PA3711, which plugs into my PoE splitter.

You’re better off shoving more that 5v up the POE then have a power regulator at the remote end - this is to avoid a volt drop on network cable … which will get worse as the cable gets longer.

I’m using a cheap regulator from China (as mentioned in a previous post), Others are using the TP-Link TL-POE20 that splits out the POE and has the regulator all in one (though that will need a 2.1mm to microusb power adapter or something)

POE can and will run what you want.


its just that people dont use the right kit.

From the wiki.

The IEEE standard for PoE requires category 5 cable or higher for high power levels, but can operate with category 3 cable if less power is required.[1] Power is supplied in common mode over two or more of the differential pairs of wires found in the Ethernet cables and comes from a power supply within a PoE-enabled networking device such as an Ethernet switch or can be injected into a cable run with a midspan power supply.

The original IEEE 802.3af-2003[2] PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA[3][4]) to each device.[5] Only 12.95 W is assured to be available at the powered device as some power dissipates in the cable.[6]

The updated IEEE 802.3at-2009[7] PoE standard also known as PoE+ or PoE plus, provides up to 25.5 W of power.[8] The 2009 standard prohibits a powered device from using all four pairs for power.[9] Some vendors have announced products that claim to be compatible with the 802.3at standard and offer up to 51 W of power over a single cable by utilizing all four pairs in the Category 5 cable.[10]

Both of these amendments have since been incorporated into the IEEE 802.3-2012 publication.[11]

I send 48v up the cable from my 802.3af switch (Cisco SG-300-10P). The only problem was the original RPi model B wasn’t grunty enough to power the USB DVB-T stick itself, hence the USB hub. The new ones have no problem, so I don’t use the USB hub.

… probably due to cost?

just to add, i do a lot of any testing i do from the loft, whilst it’s not as good as outdoors its better than being in the room with me.

This is how I have powered my RPI in my “attic” + window :smiley: :slight_smile: :mrgreen: