FlightAware Discussions

978 MHz antenna for UAT


#41

I voted yes, the current 1090 FlightAware antenna is a quality build and if the 978 antenna is similar I would spring for one rather than using my home-built one that won’t likely last the upcoming winter. Was running dump 978 for a while on a second Pi, but had trouble with it… seemed to work for a while then nada. Re-burn the card and it works again for a while.
Sometimes I would pick up several planes per day, next day nothing. Kind of hit-and-miss, being a few miles north of the Canada/US border I know there is activity I can receive here. So if PiAware had 978 incorporated and running well I would have no issues adding it (and likely purchasing the antenna if available)
I might also suggest a 978 filter like the 1090 PiAware unit too if practical.


#42

I’d rather see one antenna with a splitter to feed two sticks; I suspect the current antenna would work just fine as-is, and the hassle of having to buy, mount and cable a second antenna is going to deter a lot of folks.
IMHO, the real problem is that there are plenty of 1090 filters for use with the orange stick, but I’m having a hard time finding a 978 filter one, and I’d rather it be integrated anyway like the blue stick for 1090, though obviously in a different color.
It’d also be good if you set the (blue/new) serials to match the frequency at manufacturing so that software can be configured to reliably pick the right one without users having to run rtl_eeprom, which can be dangerous.


#43

In my experience the serial number is used only by SD card install. In any other case, the ID of the dongle is determined by the USB port that’s used by that dongle.

Also, filtering 978MHz is a much harder endeavor because the cellphone signals are “closer”. A SAW filter like is used in the Pro stick might not be effective enough. A ceramic bandpass filter is narrower, but more expensive.


#44

Ceramic filters are not narrower than SAW filters. As far as i know they might even be a bit wider but provide around the same attenuation (weakening of signal) as 2 good SAW filters.


#45

Maybe some bandwidth is still needed to properly demodulate the data. Not sure how wide it is, maybe 10-15MHz?


#46

It was already tried. It’s didn’t work great - but it was better then nothing!


#47

I found a dual 1090/978 antenna (unfortunately not available to the public yet, but I’ll update when it is). Range for 1090 seems to be the same or slightly better than the FA 1090-only antenna. 978 range seems about the same at the same altitude, but 978 aircraft tend not to fly as high. Still haven’t found a decent 978 SAW filter, so I’m running the FA dual-band filter before the splitter. Works well enough to prove it’s a valid solution, just needs to be easier to buy and set up.


#48

That would require a splitter. It means it would require also an amplifier, especially if the cable long. There is no wide band amplifier that I would trust because of many other interferences.


#49

Yes, I’m using a splitter. I’m getting ~150nm at 40kft (1090 only) and ~50nm at 5kft (both 1090 and 978). I even pick up ADS-R/TIS-B (both) regularly and FIS-B occasionally (978 only) from a tower ~15nm away despite no line of sight. That seems really good for not having an amp. IMHO, it’d be good enough for an FBO that wanted to track its planes locally–if someone packaged it into a turnkey solution, at least.

I am looking at adding amps to improve the range, of course, but there’s a lot of research to do since dual-band makes that a lot more complicated/expensive than it is for single-band.


#50

I had used two separate antennas, and planning for two separated amps/filters (I have the 1090 path already).
Sure, doubles the coax cables, but it seems simpler (for me).


#51

UAT Antenna mounted, radio/filter on the way. Waiting on the out of the box 1090/978 software…