ADSB traffic display question

AlphaPilotFlyer

AlphaPilotFlyer

Pre-takeoff checklist
Joined
Dec 15, 2020
Messages
105
Display Name
Display name:
AlphaPilotFlyer
Got an experimental EFIS unit in a C172. I replaced the original instruments with it and it’s my primary reference. The unit is pretty cool, has ADSB-in, connects to a mounted IPad and displays all the same stuff a far more expensive certified unit does. The ForeFlight AHARS and moving map work great and unit connects into pitot static lines so it displays indicated airspeed and values as well as weather and moving map. Can even shoot a GPS precision approach with amazing accuracy (VFR only of course). So it’s an all around quality unit.

I do notice that it doesn’t always display all other traffic. I realize the traffic data comes from ground stations, and notice it more when at lower alts in sparsely populated areas where there isn’t likely many ground stations. I figure its likely due to not receiving the ground station data and maybe a better antenna may help.

anyone else with ADSB traffic display notice a decrease in traffic being displayed in certain areas or have any experience with different ADSB-in antennas?
 
What ads-b out do you have? You need ads-b out to tell the ground stations to “wake up” and send traffic.
 
You should be able to receive ADS-B equipped traffic directly without this data coming from ground stations. When airborne, you will receive weather and TIS-B traffic from ground stations. If you only have ADS-B-IN, you will not receive TIS-B unless another aircraft with ADS-B OUT triggers the transmission.
 
Wait, experimental EFIS in a Cessna 172 as a replacement for primary?
 
C172 is experimental multi category airworthiness (exhibition, R&D, crew training, market survey)...video of the EFIS on www.corsairv8.com

The unit has ADSB-out, both 1090 & 978 MHz. EFIS SYSTEM is a TALOS Avionics brand, company out of Europe. Also have UAT ADS-B out onboard.

Because unit has both freq's, it should see other aircraft by air-air and not need ADS-R ground station interface. I can see all larger and military aircraft (likely 1090ES) all the time but not all the smaller GA pistons (which are likely 978 / UAT). So, I should be seeing both without need of ground station re-broadcast (ADS-R). I understand the unit will receive both air to air and air to ground data, so if I don't see it air to air, I should from ground signal if w/i range. Most of these ADSB antennas are short steel whip cut to wavelength as transponder freq (which is close at 1030 MHZ). I am thinking it may be an antenna or coax issue as the 978 equipment may be less power output compared to the 1090 transmitters.

Just wondering if anyone has similar issues. Thanks.
 
I think you meant to say you have ADS-B Out using a UAT ADS-B Out and ADS-B In from both UAT and 1090ES. What you are able to trigger from a ground station depends on several factors. Your ADS-B Out needs to include the configuration information that tells the ground station what your ADS-B In is capable of receiving. If I understand your configuration correctly, your UAT ADS-B Out has to be configured to broadcast that you have both frequencies available to receive ADS-B In with. If this is how you are configured, then in addition to receiving any aircraft of either frequency directly without the aid of a ground station, the ground station will treat you as a TISB client and will broadcast the positions of Mode C equipped aircraft that are not ADS-B Out that enter inside your hockey puck of a radius of 15 NM and +/- 3500 feet of your position. Both your aircraft and the TISB aircraft need to be inside both a radar service volume and a ground station service volume, so if you can't get radar services at your altitude and location (example in the pattern) and receive a nearby ground station, don't expect to get the TISB services until you climb high enough to receive both (radar and ground station) services. I don't think that ADS-B ground stations provide TISB service below 1000 AGL, but that may have been lowered to 500 AGL, even so, you would still need to be in a radar service area.
 
The reason you are not seeing many UAT targets is because the majority of ads-b equipped aircraft are using 1090ES. I have 978 UAT OUT in my plane. If you can receive ads-b weather when you are flying, you should be able to receive 978UAT traffic directly as well...as long as there is someone there to see.
 
Thanks for input. My ADSB out is a wing tip unit and I contacted manufacturer about what John mentioned… that my out signal may not be including I have capability to receive both 1090 and 978, but was told there was no such feature or signal option. Not sure where to go from here. Still not receiving most small aircraft targets.
 
AlphaPilotFlyer said:
Thanks for input. My ADSB out is a wing tip unit and I contacted manufacturer about what John mentioned… that my out signal may not be including I have capability to receive both 1090 and 978, but was told there was no such feature or signal option. Not sure where to go from here. Still not receiving most small aircraft targets.
Click to expand...

Obtain a PAPR report and post it. https://adsbperformance.faa.gov/PAPRRequest.aspx It will indicate how your ADS-B Out is configured and how it is performing.
 
I have the same issue. GTX 330E transponder with mode S and I don't see what I get on the iPad (dual freq ADS-B in).

Check out the target a few miles and 11:00 on the 530W on Rt 97 out of EMI....it's not on the iPad. The other traffic on the iPad near FDK isn't showing on the mode S....probably because of the distance. This was taken in the class B airspace north of BWI.

I have an extra belly mounted transponder antenna that I'm going to connect to the ADS-B in box at next annual. Could be the antenna location (rear side window) is not getting some air-to-air aircraft. But, I'd expect the terminal 978 freq to get those.
 

Attachments

  • 1CA2620D-56BB-45E5-A15E-05036005645E.jpeg
    1CA2620D-56BB-45E5-A15E-05036005645E.jpeg
    300.1 KB · Views: 9
Last edited:
In many cases I investigate, the transponder or ADS-B Out is not configured properly. That can be seen with the PAPR report.
 
You must log in or register to reply here.
Back
Top