Do I Need A Filter?


#152

Trying lowering the gain setting when using the amp. It may be too high and overloading the dongle.


#153

@Dxista @jonhawkes2030

well it looks ok to me…or not ?

and gain 38.6, after re-optimization.

stats-10-11


#154

Let me see how many posting I have made on this topic, before the FA robot tells me shut up.:joy:

Four…I think I’m ok then.:grin:

The CPU is not working as hard, good. The temperature is lower, good. Both ADSB tracks and SNR seem to be the same, but you have more room for stronger signals now, before the RTL overloads, which is good.


#155

I think you can increase the gain a little more. It should peak around the red like.


#156

thank you both guys. :smile:


#157

Hi
Have you got link for new graphs your using im still on the old frames
many thanks
john


#158

hi
no specific link, graphs come with dump1090-mutability (Joe Prochazka’s scripts).

evangel


#159

@suffolk3000

Try this method to update


#160

Ahh failed im running collectd
1.15dev and 3.5.3


#161

Help me out here - what are you trying to achieve by using a bias-t with nothing to power?


#162

@geckoVN

oh, mainly satisfy curiosity, ’ what if ', ’ does it work ', experimenting, in an effort to increase message rate.

in https://www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide/ it says :

WARNING: Before using the bias tee please ensure that you understand that you should not use
this option when the dongle is connected directly to a DC short circuited antenna. Although the bias 
tee circuit is dual protected against accidental shorts with a PTC automatically resetting fuse and
overcurrent protection on the LDO, short circuiting the bias tee for an extended period of time
(hours) could damage the LDO or fuse permanently. Only use it while connected to an actual
powered device, like an LNA, active antenna or the SpyVerter.

To make things clearer: DC Short Antenna -> LNA -> Coax -> V3(bias tee on) is absolutely fine.
What's not good and makes no sense anyway is DC Short Antenna -> Coax -> V3(bias tee on).
DC Short Antenna -> Coax -> V3 (bias tee off) is fine.

but one option not mentioned is non-DC Antenna -> Coax -> V3 (bias tee on) - if LNA is removed for some reason…


#163

hmmm … ok, but I can’t see how how it could possibly improve your signal - if it did, you wouldn’t need an amp.
Similarly, I don’t understand why turning the bias-t on had a detrimental effect - perhaps someone with an FA filter and a multimeter could check to see if it presents as a short circuit?


#164

Ok the FA filters arrived on Friday and they did what I expected and what a few already new. Basically the noise around 870 to 890 has practically disappeared. The noise around 942 to 958 is still high.

The good news is that the reduction in the 800’s has allowed me to get a similar range and hits on my Dev box (FA Pro, FA ANT) as my other Prod set up (FA Pro with Spider - gain 44.5).

TBH is expected additional range with the DEV set up but that’s said I am still mucking around with gain - currently set to 38.6… perhaps I need to lower further.