Messages

211

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: June 13, 2019, 01:43:44 am »

Yes, that is certainly my plan, Keith 

It has been quite a steep learning curve for some of the Pi things. I literally had never even seen one until I set this thing up and I had no idea what an SSH or an FTP was. I don't claim to understand the code being written to my Pi but I'm getting pretty good at copying and pasting the codes suggested on the RF24 Forum and at least I can now talk to my Pi though my MacBook's Terminal (something else I didn't know existed).

I think program writing has moved on a bit since I used punched cards and BASIC for my O level computer studies (admittedly we did get super advanced for A level and used a fancy BBC B computer with a tape recorder to save our programs) but I think I might see if there is a book or YouTube course to see if I can get to grips with some of this Pi code and write my own program for spelling rude words. I assume that's what kids are still doing.

Yes, an OGN-R station will be fun 

212

Technical Support / Re: Pilotaware is unstable

« on: June 13, 2019, 01:23:22 am »

I would also say that comparing what your receiver is receiving versus FlightRadar is a bit optimistic. FlightRadar is being fed by many people, with dedicated ADSB receivers and more types of feeds. They have ADSB, ModeS MLAT etc, whereas you are just looking at ADSB at the moment (unless a PAW aircraft flies over or you're within range of an OGN-R station).

To try and demonstrate what I mean I will attempt to attach a couple of screenshots taken within a few seconds of each other from my house. One of them shows the FlightRadar picture and the other shows what my dedicated ADSB receiver is showing in my house. This is with a pretty big collinear antenna mounted above my house and about 35m above sea level, with flat ground/ocean surrounding me. I normally see aircraft out to 225nm. Compared to your antenna sitting indoors and lying horizontally I will be picking up many more aircraft but see how I only have one (the Flying Doctor) compared to the FlightRadar picture. You will see a lot more traffic if you do as Peter has said.

213

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: June 12, 2019, 02:52:52 am »

Welcome to the geek side! You'll be happy here.

It is quite a lot of fun. A few days ago I didn't have a clue what Dump1090 was and now I have a fancy map, with rssi numbers telling me 'stuff' AND a fancy, in-built, gain changing button AND all sorts of graphs

I think the antenna is happier for being re-erected as I've broken my previous record 

214

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: June 10, 2019, 01:40:59 pm »

I replied the other day when someone called into question unmet PAW promises, while he flies with a unit where most of the 'snake oil' that was promised never came to fruition. Then I thought, 'why am I bothering' and deleted the reply. Luckily nobody was awake in the UK to see what I'd said.....I think maybe a bit too truthful and close to the edge 

Anyway, 220nm is my new antenna record 

215

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: June 10, 2019, 06:49:59 am »

Well, I am pleased to say my collinear antenna works. I haven't compared it yet to my spider (and then a spider that I'll build that is the same as Alan's) but my maximum range detection so far is 208.4nm, which I don't think is too bad.

I had a bit of an incident last night when the horribly strong winds we'd been having blew down the pole holding my little weather station thingy and the ADSB antenna. The weather station is no more but my antenna now has the pole all to itself and seems very happy, despite the 40-45kt winds blowing at the moment. Small wonder the only traffic I'm really seeing is going into Perth (about 80nm north of me). No GA out today from Bunbury 

I've now become a thorn in the side of the FR24 forum but I now even k now how to SSH my Pi and have actually loaded some programs to look at my 1090 performance graphs and map. It's all quite exciting but maybe I just need to get out more 

216

Technical Support / Re: PilotAware Rosetta- Trig TT21- Wiring Loom

« on: June 10, 2019, 01:11:53 am »

As the forum rank amateur I would also check to see how close your radio and transponder coax cables are. If you are getting transponder 'clicks' through your headphones it may be just a simple matter of the two coaxeseses being too close to each other.

217

General Discussion / Re: 360radar network

« on: June 04, 2019, 08:56:04 am »

Hi Tony,

I'm sure I'll be corrected if I'm wrong but 360Radar receives Flarm and ADSB and uses Mode S for multilateration. They do not mention PAW reception, nor data through the OGN-R network.

It does seem a shame, though, that since PAW knows where it is (same as ADSB) and 360Radar signals come from OGN-R stations to the aircraft, that PAW doesn't go the other way and send position data from the aircraft to 360Radar via the OGN-R stations. It would save them having to multi-laterate (is that a real verb) if the aircraft had PAW and Mode S but no ADSB Out.

218

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: June 01, 2019, 12:13:20 pm »

Well, today I have mostly been playing with bits of coax  I made the collinear antenna yesterday and managed to get it up on the roof and the cable run to where my Raspberry Pi etc will live. It's now just waiting for the new dongle and other bits to arrive.

I did also make a spider antenna with eight legs (as all spiders should have). To say that I used Australia's supply of solder would not be an exaggeration. I really am not very good at all but none of the bits of wire are going anywhere, that's for sure. More is more will be my soldering moto. One day I may post a photo of the antenna but I'm too embarrassed to right now 

I used 8 sections to construct my collinear antenna. RG6 cable (75 Ohms) and made the lengths 116mm each.

When you see a Homer Simpson-esque explosion over Western Australia you will know I have got the other bits and pieces and plugged it in 

I apologise for the crap standard of photographs but they've been shrunk and resolution reduced so they fit on this forum.

219

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: May 30, 2019, 01:53:27 am »

I am very glad I asked and your explanation is both easy to understand and very helpful. Thank you 

The sleeved dipole looks like the easiest to make.

The one in the YouTube video is also very simple and looks like it gives very good results if you use 16 sections of 11cm coax (I knew I shouldn't have chopped that 1.8m antenna cover in half  ). There are various comments about shorting things out and resistors but the OP says to ignore all that and just use RG6 cable as it works.

The spider looks like fun to make 

I think today I will investigate local suppliers if coax.

Thanks again, Paul 

220

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: May 29, 2019, 03:09:21 pm »

OOoooo, that sounds easy and within my capabilities 

SO, just one question; why do half a wavelength and not a whole one e.g 136mm of inner core of the coax and 136mm of the braid folded back down the outside of the coax (all inside the fibreglass tube)?

221

General Discussion / Re: New version of PAW

« on: May 29, 2019, 02:37:30 pm »

Plan A seems to be 2 June (from a post on a different forum  )

222

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: May 29, 2019, 02:29:16 pm »

Thanks, as ever, Paul (I think  ) I'll get to the bottom of all this stuff one day but I seem to be gaining a little understanding each time I ask something, so it's not all bad.

If you want a higher gain antenna, you must then add elements. You can do this in the shape of a yagi, like a TV aerial, but then it becomes directional. If you want to have an omnidirectional antenna with more gain, elements must be added in-line with the first. This is known as a colinear antenna. You have to either feed the elements separately in phase (a stacked dipole) or you "hide" the out of phase half wave in a section of transmission line or a coil.

I think what you describe is the one I thought I would get by sticking my 275mm bit of coax inside the fibreglass tube (it looks nice) and connecting it to the N-type connector (see picture of proper one below and what I thought I was going to get). It would seem that I am somewhat off the mark 

I did see that antenna with the three bends in it on YouTube and thought that was 'doable'. I haven't yet watched the video you linked to but the one I watched was an English voice in South Africa and he talked about it being a directional antenna.

In summary, I think I should abandon the idea of a nice-looking 275mm bit of coax inside a fibreglass tube and concentrate on making a spider to sit atop a pole on my roof 

(I do like the animated explanation......it actually makes a lot of sense).

223

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: May 29, 2019, 10:16:10 am »

Just to bore a little further, I thought I'd share my thoughts of being 'ripped off' with the marine VHF antenna. Today I cut it open to see what was what and found that my 1.8m aerial was, in fact, 2/3 full of air. The fibreglass tube extended the full 1.8m but the coax inside was a measly 0.6m of RG58. I always thought it was mighty impressive that I was getting better VHF ranges on the boat because of the length of my antenna but, alas, it would seem I fell somewhat short (I seem to recall my wife saying something similar) 

Anyway, it has given me a couple of bites of the cherry for when I cock something up with the 275mm ADSB antennas. I am going to procure a couple of N-type connectors tomorrow and then have an N to SMA coax cable to my ADSB dongle.

If the soldering on it is anything like the bodge I did of soldering my old MacBook's charger today I think I'm going to need a LOT of heat shrink to hide the blobs and mess 

Now I'm wondering if I need some sort of ground plane, since it isn't anything fancy inside the fibreglass but a length of coax. As I understand it, those vertical antennas you see (with no bits sticking out the sides etc) are more complex inside than a straight bit of coax cable. I get the feeling I'll need some sort of plane twixt the antenna and connector but, now I've gone for the 275mm antenna length (1 wavelength) I think the ground plane will have to have the same radius.

224

OGN-R PilotAware / Re: ADSB Ground-Based Antenna

« on: May 28, 2019, 12:37:39 am »

Thanks guys for your replies.

I shall take a closer look at the lowflyingwales website and see what information I can glean from there. A lot of what I've been looking at has been on the Flightradar24 and Flightaware websites. I expect a lot of it is repeated but it is interesting to read, nevertheless.

Alan, I do have a couple of ADSB 'whip' antennas but they are in a box in the UK. I already have the Flightaware Pro ADSB dongle, so I thought I'd buy another one but it comes without an antenna. I expect I will end up constructing a spider (like yours) as they seem pretty simple to do and their popularity must mean they do a pretty good job. I was just wondering about modifying my spare boat VHF antenna just because then it would look semi-professional, like the outdoor ADSB antennas you can buy. Just in passing, what sort of reception range do you get from the spider antenna you've built?

It's all a bit of fun, this project and I'll probably feed the results to Flightradar24 but it's all good practice for when we go to the UK and I set up my OGN-R station (one day).

225

OGN-R PilotAware / ADSB Ground-Based Antenna

« on: May 27, 2019, 10:15:24 am »

I know here be dragons and talks of Raspberry Pi codes etc but I thought I would venture here with a quick question.

Just for a laugh I am going to attempt to set up an ADSB receiving station at my house (in Australia). I've ordered a Pi 3B+ and I have a nice ADSB radio/dongle thing but I'd like to know if I can modify an antenna to get a decent external aerial for my house instead of (a)spending more $$$s on eBay/Amazon (b)bending bits of 69mm lengths of wire and scaring everyone with spiders on the roof (there's already enough of those buggers in these parts).

I have a spare GME VHF marine antenna. Obviously it is too long but I was wondering if this could be cut down and a suitable connector welded/soldered/glued to the base with which to connect the coax to the RTL dongle thingy. I think I may need to install an amplifier in there somewhere but now we're getting high-tech and I'll just take one step at a time.

As it's started life at 1.8m I assume I'll have to cut it to 276mm. Does that sound right?

Anyway, not a huge deal if it can't be done but I'd appreciate any thoughts you might have on my hobby project 

This is pretty much the antenna I have: https://www.gme.net.au/catalogue/antennas/vhf-marine-antennas-and-whips/ae346v.aspx