ADS-B CoCo on a PWS pole


#1

At last my local TV antenna friend has come round and moved my ADS-B 8 element CoCo in a 20mm polypipe onto the mounting pole which holds my Davis Vantage Vue Personal Weather Station and the increase in performance is fantastic. To the south that is. However, the polypipe is only about 2 inches away from the 50mm aluminium pole and performance is split on a W-E basis. Almost every thing in the southern hemisphere of the SPLAT is out to 190 - 220NM and most of the stuff in the northern SPLAT hemisphere is out to about 75/80NM with aircraft on the 310 - 330 radial disappearing at about 125NM. I reckon if we can find a mount that will hold the CoCo out about a foot or more (30cm+ for our younger viewers) that would greatly increase reception to the north. Does anybody have any thoughts on whether this **would ** increase performance or not, and most importantly any ideas on where such an offset mounting could be purchased/how it can be made in my man cave? The photo shows how things are mounted and the PWS is oriented N-S with the anemometer end pointing N

Many thanks for reading
A342


#2

The metallic pole that you are attached is a “shield” blocking the signals.
Also the metallic clamps don’t help - they need to be on the parts of the CoCo that have the signal inside the coax cable. As it is now, you have a 50-50 chance to be correct.


#3

Firstly i would make the plastic pipe longer than it needs to be and mount the clamps only where the antenna is not.

Or at least place the clamps right at the edges of the current pipe that should be good enough.

On mounting away from the pole, yes that will improve reception and you will only be blind on a very small part of the sky.
I’m not sure how to do it though, wind will induce a twisting motion on the antenna pole that was not there before, you will have to make sure it can handle that.

At the top you could use two poles to make a triangle and fix the antenna top at the end of that triangle.
The bottom would then be sufficient with one pole.

Or both poles need to be rigid enough that you don’t need a triangle.
I’m sure something like this can be acquired but i guess it won’t be cheap.


#4

get something like this

Use one of your present brackets to mount it on your mast to go past your weather station equipment, then mount the bottom of your ADSB antenna to the top of the new mast using the other single bracket


#5

Peter excellent idea. And if I mount it on the south side of the pole it shouldn’t make much of a difference to the airflow to the anemometer. I’ll have a chat with my TV man and see what he thinks.

Many Thanks


#6

We have one of the Davis Vantage Vue weather stations as well. I have avoided mounting my antennas on the same pole for the reasons you encountered, as well as the fact that my understanding is that the sensor station communicates with the base station using a some type of spread spectrum wireless signal (902-928Mhz) that I wanted no close interference from.

Is it really a problem ? I don’t really know but wasn’t about to test fate.


#7

Skip,
Many thanks for your reply. Firstly the good news. My antenna is an eight element CoCo suspended in a 20mm polypipe. It has now been up for over 24 hours and I have had no problems with interference The Vantage Vue is transmitting in the frequency range you have stated. The CoCo however is receiving only, and at a frequency of 1.09Ghz. I have to admit that it is now 58 years since I studied any antenna theory (40 (Ulster) Signals Regt. T&AVR II) but I seem to remember that there should be no interference FROM the CoCo. However, if the s had a powerful transmitter rather than the minuscule 30Ma stated it is possible that the signal from the CoCo might be corrupted.

As for the antenna being shielded, another FA respondent has suggested mounting a cranked 1” aluminium pole as near to the top of the Davis pole as possible (I would suggest on the south/solar end to mitigate any flow problem over the anemometer cups) and thereby being able to mount the CoCo above and behind the Vantage Vue, thereby taking it out of any shielding/shadow. I shall try this and also change the somewhat agricultural heavy duty steel mounting clamps provided by my friendly TV man. If you wish I will let you know how I get on with this.

Regards

Mike Wilson

Bangor, Co. Down


#8

Install a horizintal pipe as as extender arm and install your CoCo on it, something like FlightRadar24 user lutorm did to mount his 1090 MHz Franklin on the pipe already having a 2-meter J-Pole.

CLICK ON IMAGE TO SEE LARGER SIZE
CLICK AGAIN TO SEE FULL SIZE


#9

Mike, in my case the concern was about the Vantage Vue transmitter possibly introducing noise into the ADSB signal received- there should be no impact on the weather station operation caused by the FA antenna. Many folks ( particuarly in urban environments) have issues with Cell frequencies and other neighboring services swamping the relatively weak ADSB 1090Mhz signal with interference. You will see many conversations here about how to determine whether additional filters are required if you search or browse through the discussions.

Good luck with your installation, and did you build the CoCo yourself ?


#10

Skip,
Thank you for your good wishes. Yes, I built the CoCo myself with eight elements, using RG6 Co-Ax. A 50m reel in our local hardware chainstore cost £8.50 ($6.00 U.S.) I live in a suburban area of Bangor in Northern Ireland and have not noticed much noise (but don’t have the instrumentation to prove it) Suffice to say I am happy with over 230nm to the south and hopefully will get a more circular splat (splot? i’m new to this terminology). I’m fortunate in that I live in an area where the majority of Western European/UK flights from/ to Canada, The U.S.northern east coast and the west coast overfly en-route to their entry/exit points to/from the northern NATS tracks. I have an iComm RC 20 and can listen in to Scottish (Rathlin West Sector) ATCC. With two commercial airports and a GA field close by it’s a rich environment for aviation hobbyists of every ilk.

Regards


#11

If your traffic is predominantly in one direction then installing the antenna on the appropriate side of the pole will minimize missing reports.

For example, 90% of my traffic is E-W so I would mount the antenna on the N or S side of the pole.


#12

Your dongle (DVB-T or Pro Stick) + your computer (RPi or Windows laptop/desktop) is sufficient to find out existing RF interference at your location picked by your 1090 Mhz antenna. Please see this thread:

Do I Need A Filter?

.


#13

Skip, Robwell,a567 and others.
That’s what I like about this site, no one flames you for lack of knowledge, rather the reverse. Skip, I spoke with a pleasant chap at Davis who informed that the Vantage Vue ISS on sale in the EU uses a frequency spread of 868 to 868.6 Mhz. As you will see below, I don’t think that the Vue is causing too much trouble, though I would like those with the knowledge to interpret the scan.
Robwell, as I wrote to skip above I live in what, for me, is a fairly intense area of aerial activity, what with the Rathlin West sector of the Scottish ATCC vectoring loads of traffic through my area onto the North Atlantic Track System, via Shanwick.
abcd567, thank you very much for directing me to the “Do I need a Filter” thread. It has greatly increased my theoretical knowledge of receiver antennae (but LOADS of reading to be done in that area) Yes, I think (know) that I do need a filter. Can you advise me which would be best, based on the scan results below. My TV man has installed a Swan Neck pole onto the PWS pole but is reluctant to mount it too far up for fear of any twisting moment affecting the K mounts in a strong wind. He’s the professional so I listen to what he says. Unfortunately the CoCo is still below the level of the PWS and is not only still in the shadow of the main pole but needs to be about two meters higher to clear the buildings immediately above and behind me to the West, North and Northeast. I propose to do that by building another CoCo, but this time using RG6, and mounting it in a 3 metre polypipe, ensuring that it is secured to the top of the pipe, thereby keeping the CoCo itself clear of the ironmongery mount and gaining height with very little increase in weight (twisting moment) Now the big question. Is my eight element CoCo, which is giving me great results compared to what I started out with, OK or would a 12 or 16 element CoCo be more efficient? Oh yes, what’s all that activity between 920 and 960 Mhz. Mobile/Cell activity?

scan1a
scan2A
scan3A


#14

Why do you think you need more elements (gain)? Are you running at the max gain now?


#15

.
Yes, ALL the activity shown in two pieces of scan below is Mobile/Cell/Pager etc. You SURE need a good filter to get rid of Cell/Mobile signals between 925 Mhz and 965 Mhz
.
scan1a
scan2A


#16

Hi A342,

I used to have a home built 16 element CoCo made from a generic coax. I eventually worked out that the Velocity Factor was 0.66 so cut my elements accordingly. I then placed it in some 22mm plastic waste pipe and mounted it at the apex of the roof. It worked very well until we had a winter storm and the pipe snapped just above the mounting point. It used to swing about a lot in light winds so I wasn’t surprised it eventually broke.
Make yourself a 12 and a 16 element CoCo and test them outdoors but not up the pole on the roof. You may have read on this forum that a lot of people have trouble making a CoCo that works, so congratulations on your build :smiley:

As others have said, you need a filter to remove the unwanted signals in the 900 Mhz band. You seem to be a DIYer so take a look at a thread I started about Interdigital filters.
[Note] I have NO experience of radio/physics etc. apart from what I’ve learned on this forum and a lot of reading :wink:


#17

@A342

I will recommend that you follow @triggers advises and guidance.
He has a long experience in CoCo making, and has successfully built several very good CoCos.

He has also ventured in saw, cavity and inter-digital DIY Filters, as well as Directional antennas like Yagi & Corner Reflector types.


#18

However, most of them ended up in the bin but it was good experience.


#19

I don’t know. I’m new to this particular bit of following aircraft via ADS-B and am adding, hopefully, to the UK coverage. It’s nice to know that those with knowledge like to share it. I was EXTREMELY surprised when I tried my first cantenna a few months ago and even more surprised when the tin of beans performed better than the tin of peas.


#20

Triggers, abcd567, thanks for all your advice. Triggers I will most certainly look at the thread you recommend. Yes I will try the various numbers of elements and hoist them above my man cave for comparison. As for experience, I left school at 14 years and ten months of age (armed with a National Bicycle Safety Certificate) to start working life as a Chemists (Drug Store) delivery boy. Since then I have graduated from the School of Hard Knocks and am working on my Masters in the University of Life. Yes, my children think I am a little mad.