Couple of questions

[ROBSTYLES]

Afternoon all
OK I’ve been playing with different antennas over the last few days and settled on a coax collinear. Two questions , I’m receiving on average about 30 or 40 aircraft with a messages rate of around 250 but every now and again that just drops off to 20 and around 50 messages per second. Then over a short period go back up to the first figures. This is in a space of 15 mins. I understand planes drop off etc. But this is quite a drastic drop. My thoughts is interference but any thoughts. Next question is a bit loaded I know but is 40 to 50 total aircraft with 30 with positions and 200 messages per second poor, OK or good. Thanks

[jonhawkes2030]

Check out @abcd567 posts on gain optimisation.

Tweaks

INDEX To see details, click on the Tweaks below or scroll down TWEAK #1: RANGE CIRCLES (a) Additional Range Circles (b) Coloring Range Circles Alternating Red/Blue + Making Circles dashed line instead of solid line. TWEAK #2: REPLACING TWO-CLOCK MAP BY SKYVIEW MAP Replacing Map having two clocks (dump1090-mutability) by SkyView Map (dump1090-fa) (a) Keeping dump1090-mutability, but replacing Map only (Skin/GUI replacement) (b) Uninstalling dump1090-mutability, and in its place installing…

He also has great stuff to see if you need a filter.

Do I Need A Filter?

The space around ADS-B antenna contain not only 1090 MHz signals, but also lot of other signals at different frequencies. The closer the frequency of a signal to 1090 MHz, your ADS-B antenna picks it stronger. For example if there are three signals of equal strength, one at 144 MHz, 2nd at 850 MHz and 3rd at 950 MHz, the ADS-B antenna will pick 950 MHz one the strongest, 850 MHz one a bit less stronger, and 144 MHz one much fainter. As the Cell/Mobile/Pager signals exist in the range 850 MHz to…

Look at the stats for the receivers near you. They will give you an indication of what you can expect.
Dennis Perry ADS-B Feeder Statistics - FlightAware seems to do very well. It is possible that they have a better location(ie higher or less interference).

[ROBSTYLES]

Thanks for the replies, tried gain setting and -10 agc seems to work best for me. Agreed with the interference, I’m located at a high location and the antenna is also on the roof so inevitably really. I’ll have to invest in a filter and hopefully that will help.

[ROBSTYLES]

Thanks John, some nice tips.