Antenna Extension Cable - Is this the right one?

FlightAware ADS-B Flight Tracking
22

Reason I tried using a network cable was because of distance.
I did the same thing many years ago with a web cam, but then with 20 meters of cat5e cable.
Was this cam https://www.download.p4c.philips.com/files/p/pcvc840k_00/pcvc840k_00_pss_enggb.pdf
From what I recall I had no problem there. Not sure how data rate cam is compared to this USB stick.
A way of testing this with adapters you mention is to connect a USB memory stick instead of the more
expensive ADS-B receiver. Test how long it takes to transfer a large file both ways with and without
a long network cabel.

23

I wouldn’t be surprised if you have mlat problems with that cable.

24

I fail to understand the mlat problem, but i’m a “green” with this stuff, but have some insight.
Some facts: Wires in a cat6 cable is usually some thicker than wire used in a everyday USB cable.
Cat6 cable usually use 23AWG wire (Some cheap use 24AWG). Voltage drop 5 volt and 50 feet
with 23AWG wire is approx 0,1 volt at 300mA (1 wire VCC and 1 ground). In my case I use 1 pair
(2 wires) for both VCC and ground) - Voltage drop close to zero at 300mA)
USB specifies 28 AWG for the signal pair, and 28 to 20 AWG for the power pair. 28AWG is rather
thin for supplying 500mA (the maximum current that USB 2.0 specifies for power), and will result
in a high voltage drop for long cables. Most USB cables use 26 or 24AWG for the power pair,
or even bigger (typically 22AWG) for the longer ones (~3 meters).
A calculatore for cat5 cable : http://www.netkrom.com/legado/voltage_loss_over_cat5_calculator.php?re2=cal&item=resources
Just some ideas :slight_smile:

25

Instead of mounting the receiver remotely from the Pi, I mounted the Pi at the receiver and powered the lot using PoE

1000×314 57.6 KB

The power is carried over the Ethernet cable at 48V and converted to 5V at the Pi so no power sag. Here is a suitable IEEE802.3af splitter

Here is a suitable 48V compliant injector.

You can choose to use the Ethernet for power and comms or if you prefer WiFi the PoE can be used just to provide reliable power.

My two local Pi are mounted up under the eve about 2 cable metres from the antenna base.

S.

2 Likes
26

The dongles are sensitive to USB bus noise as there is no buffering / retry mechanism for messages damaged by noise; dropped data interferes with mlat timing; long unshielded cables (or even if you shield them properly) are going to increase the USB error rate.

28

Feeding 5V on long PoE cable may cause excessive voltage drop and low voltage at RPi.

For long PoE cables, a 48V DC supply at router/switch, and a down convertor to 5V at RPi works satisfactorily.

Po_E_48_V.png

Below is one such complete kit . This item is given as an example for guidance only. If you search Amazon and eBay, you will find many other makes and prices.

https://www.amazon.com/itm/dp/B004UBUB7C

The kit contains:
Power Adapter AC to 48V DC
Power Cord
PoE Injector 48V DC
Ethernet Cable
PoE Splitter with integral down convertor to 12/9/5 V DC (dc output voltage selectable by a switch)

Above kit is NOT AF Compliant. Non-AF Compliant POE will fry your non-POE devices if you plug them in without the POE splitter.

Go for AF-compliant POE. It will only apply power after being “asked” for it, and will protect non-POE devices, if you plug them in.

AF-compliant PoE:

Injector TP-Link TL-PoE150S
https://www.amazon.com/gp/aw/d/B001PS9E5I

Splitter TP-Link TL-PoE10R
https://www.amazon.com/gp/aw/d/B003CFATQK

Injector User Guide / Specs:
Injector_Guide.pdf

Splitter User Guide / Specs:
Splitter_Guide.pdf

,

29

He’s not using it to feed the complete RPi but only the dongle.
Lower amperage means lower voltage drop.

@steinrar:
Nicely done! :wink:
Too bad your ADS-B site isn’t visible: steinrar ADS-B Feeder Statistics - FlightAware

1 Like
30

Hi @obj

Will FA continue to support MLAT a year or so from now, when it becomes mandatory for all planes flying above a certain altitude to be ADS-B capable? If yes, what would the advantage/benefit be?

Thanks.

31

That’s not the case for the entire world and as you already stated it’s not mandatory for all altitudes.

I would be surprised if they switched off MLAT as the main cost of such a system is creating the infrastructure.
Keeping it alive isn’t that costly i believe.
(might be mistaken, don’t know how much CPU grunt it requires)

Also there are sometimes transponders not working, they could start doing spot checks for gross position reporting errors :slight_smile:
(big errors like 100 km off)

32

The world is larger than the US; and even in the US there’s plenty of aircraft that aren’t required to have 1090MHz ADS-B out.

33

Half a dozen blades (x2 for geo redundancy)

34

True, but any plane flying into US air space, and meeting the FAA conditions, will need to have an ADS-B transponder regardless of country of origin or registration. I’m in Canada, near the border, this is why I asked. Our friends in Europe, and elsewhere, need not ‘worry’ about it.

It was just a curiosity. I disabled MLAT some time ago, there is no impact on my ‘operations’ one way or the other.

35

My point was that there will continue to be plenty of non-ADS-B traffic to look at, so mlat continues to be useful.

36

OK, thanks. That’ll be the raison d’etre for the system past 2020.

37

rai·son d’ĂȘ·tre

/ˌrāzîn ˈdetrə/

noun

  1. the most important reason or purpose for someone or something’s existence.

“an institution whose raison d’ĂȘtre is public service broadcasting”

Just if anyone else isn’t quite haute couture enough to understand that.

38

Did you expect a prĂȘt-Ă -porter post?:rofl:

39

Greetings again !
Just installed homemade antenna a couple of meters in a mast above roof at my house.
Now claimed my PiAware Ground Station link. Will enter position data for MLAT once link
is up&go. Will then see what’s left when the smoke settle :wink:
Location is so far northwest in south noway that the seagulls are screaming in English I think.
Nearest airport is BGO, approx 40km from my location.

40

Photos & details of antenna will be highly appreciated.

42

Whatever abcd567 :slight_smile: Basic of the antenna here: https://www.balarad.net/
In picture 1 i have omitted the resistor and connected a copper wire 1/4 wavelength
= approx 6,8cm. You can use many coax “elements” , better gain for each element.
I have used 2 as I don’t want it to big as it is attached directly to ADS-B receiver (Weather/wind)
Each coax element should be 1/2 wavelength multiplied with coax velocity factor used.
You find some info here: EI8IC's Coaxial Cable information page
I personally used wifi antenna for 2,4GHz, opened the joint where you bend it, cut the
coax there (You are left with approx 1 cm of coax you can work with, but it is enough).
Soldered that piece (feed line) together with antenna “build” mentioned above.
Removed the antenna/wire inside the “broken” antenna and put it together again
with new “antenna” antenna inside).How it’s done will wary with wifi antenna used.
You will need a SMA gender “converter” as both receiver and wifi antenna is female connectors.
( I skipped last part and used a tiny copper wire in between to make contact)
Used a shrink-on hose to “lock” the wifi antenna from bending in the joint, and also for weather protection.
Question: Is this https://flightaware.com/adsb/prostick/ “grounded” to protect for static ?)

1 Like
43

Be aware that WiFi antennas usually use reverse polarity connectors to other radio equipment, termed SMA-RP. A misguided attempt to prevent people using antennas and equipment to boost their wifi range - obviously no one thought that people would just make the stuff with those connectors on or adaptors to make it fit.