XGPS170 - Better ADSB reception needed in a/c.


#1

Hello:

I have a Dual XGPS170 that seems to work OK at lower altitudes, but when we cruise at 40,000 feet, the reception is very spotty, to the point that I am about to give up on it. I use it with FltPlan.com’s GO-app, on my iPhone 6sPlus, in a Cessna Citation Excel, C56X.

What I am doing now is mounting the Dual XGPS170 in the side window of the a/c that does NOT have the electric heating elements using those Command picture hanging velco things that you can get at Home Depot. I contacted Dual, and they sent me the “new style” antenna that they are, apparently, now shipping with the unit. This new style antenna did help, I at least get some ADSB sites now at 40,000 feet, but nothing very consistent.

I was wondering if anyone knew of a inexpensive (under $100) way do get better reception? According to Dual, “The antenna form factor on XGPS170 is a SMA connector. We also recommend using the RG400 cable, and keeping at least 30” between your transponder antenna and the new ADS-B antenna.” The last part is easy, as I’m trying to mount this in the side window. But I just thought of this as I’m writing, unless there is an interference issue with the top TCAS antenna on the roof of the a/c, not exactly sure where that is located in reference to the side window.

An external antenna mounted on the aircraft (those Shark fin looking types) is not going to happen, according to the boss man. So that is out of the question.

Any suggestions would be greatly appreciated.

To clarify what I am looking for, I’m not really looking for traffic information from the XGPS ADSB, we have TCAS for that. Rather it is the weather information I’m looking to get from the ADSB. Especially now that Flight Watch services have been cancelled.


#2

This is a 978MHz receiver, right? You may just be suffering from a lack of 978MHz traffic in general. Do you also have ADS-B out on 978MHz? I believe the way that the ground stations work, they only send TIS-B / FIS-B when they believe there’s a UAT-equipped aircraft around, and that’s not hugely common.

I don’t know exactly what the antenna you have looks like but be aware that the signals are vertically polarized so the orientation of the antenna is important (it should be vertical).

As a sanity check you could have a play with Stratux (reddit.com/r/stratux) which should be on the order of $100 to get something running.


#3

You can have a Mode S with ES as your ADS-B out. Then, you can also have a 978 UAT in for weather. Dynon Skyview is an example. But I don’t think you can get 978 UAT-in unless you’re transmitting ADS-B OUT via 978UAT OR 1090ES. I believe this is a recent change that the FAA made to help force people to get the equipment to do ADS-B OUT.

In other words, if you don’t help ADS-B by giving your position (via 1090ES or 978UAT), then you are no longer allowed to benefit from ADS-B. Only by chance will you pick up anything. If you happen to by flying near a compliant aircraft, you might intercept that data.

But, if you have ADS-B out, you will receive all known traffic. It doesn’t matter which frequency the aircraft is reporting its position. The ground station will combine them all together and send that to the local aircraft…TIS-B if receiving traffic via your 1090/1030ES transponder…FIS-B if receiving your traffic via 978UAT. But the weather is only available if you have ADS-B IN via 978UAT.