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 Post subject: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 8:52 am 
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dbaker - FlightAware user avatar

Joined: Mon Jul 25, 2005 12:00 am
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Hi, everyone.

Good news -- our custom 1090MHz ADS-B filters are now for sale!

In the US on Amazon, $19.95: http://www.amazon.com/dp/B010GBQXK8?tag=fligh01-20
Worldwide on eBay, $24.99: http://rover.ebay.com/rover/1/711-53200 ... =824&kw=lg

Both options are less than half the price of filters available elsewhere. We're selling these at cost to help improve ADS-B reception for the community.

They have SMA connectors (male and female), pass 980-1150MHz with an impedance of 50ohms and insertion less of <2.5dB.

Image


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 9:50 am 
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strmchaasr - FlightAware user avatar

Joined: Sat Jun 17, 2006 2:00 pm
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starting to run into to many adapter issues. Whether its the FA antenna going from N to F and then coax. Now this needs FA antenna N to SMA to filter then SMA to F and then my coax. I do have a MCX to SMA male to go from dongle to the filter...but then need from Filter SMA to F then coax to F adapter to N connector on the FA antenna non seem like a good way. so many conversions...would be another 10 bucks or so in different adapters


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 10:34 am 
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clipsnotebook - FlightAware user avatar

Joined: Wed Jun 03, 2009 1:00 am
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Just curious - Do Flightfeeders also get one of these? The one supplied earlier decreased my range and count


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 10:37 am 
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dbaker - FlightAware user avatar

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clipsnotebook wrote:
Just curious - Do Flightfeeders also get one of these? The one supplied earlier decreased my range and count


It depends on the model of FF since some have an internal one.


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 10:39 am 
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clipsnotebook - FlightAware user avatar

Joined: Wed Jun 03, 2009 1:00 am
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Rpi+Nuand boards


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 11:53 am 
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vannossc - FlightAware user avatar

Joined: Tue Apr 21, 2009 8:00 pm
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strmchaasr wrote:
starting to run into to many adapter issues. Whether its the FA antenna going from N to F and then coax. Now this needs FA antenna N to SMA to filter then SMA to F and then my coax. I do have a MCX to SMA male to go from dongle to the filter...but then need from Filter SMA to F then coax to F adapter to N connector on the FA antenna non seem like a good way. so many conversions...would be another 10 bucks or so in different adapters


Agree. I'm going to wait for the HAM fest coming in a few weeks to discuss options for a N-type to 50 ohm cable to SMA-type solution. Short length, 10 feet.

I hate adapters. Was taught to use adapters to test equipment or to save a life. Otherwise, you're throwing away signal and satisfaction.

Have mine on the way. Have the FA antenna too. Up and working - prob a +10-15% improvement over a 4 leg spider. Planning last and final antenna installation (when wife away...) on the garage in late September so I want all things in order. 26 ft peak, 5 ft mast, laptop in garage loft with 10 ft USB cable up to new ver RTL dongle.

Scott


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 11:59 am 
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N456TS - FlightAware user avatar

Joined: Sat Nov 08, 2014 11:58 pm
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Nice!


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 12:09 pm 
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strmchaasr - FlightAware user avatar

Joined: Sat Jun 17, 2006 2:00 pm
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now says out of stock till the 21st


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 12:14 pm 
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dbaker - FlightAware user avatar

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strmchaasr wrote:
now says out of stock till the 21st


I think that's a glitch, but worst case, that's Friday.


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 1:55 pm 
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david.baker - FlightAware user avatar

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Filtering is one of those things that you either don't need it at all or you need a lot of it. Here is a brief rundown on why some people need some band pass filtering.

The max range of your system depends on the Signal to Noise ratio. The more signal (frequency we want) to noise (any frequencies you don't want) the futher away your system can see planes.

The FlightAware band pass filter has a 1.5dB insertion loss at 1090MHz and 2dB insertion loss at 978MHz. Other frequencies will have a 30dB of rejection or more. You are going to lose a bit of the 1090MHz signal (1.5dB loss) but it will absolutely remove any other frequency on the cable (30dB rejection). If you are close enough to other radio systems (cell phones are @ 700MHz - 900MHz or 1400MHz+) the filter will remove these unwanted noise signals and improve your signal to noise ratio. This should increase your range.

There are two types of noise sources that you probably have to worry about:
1) Cellphone tower or close to an electrical motor (elevators motors, AC units, and heavy machine shops are extremely noisy).
2) You are using an amplifier. Amplifiers are wide band and amplify everything (Amplifiers have their range written on the case and this usually includes cell phone frequencies.). You can actually lower your signal to noise ratio because of the wide band nature will amplify the noise as well as the signal. If you are seeing a drop in range after using an amplifier then you need extra filtering. If you are seeing only a marginal improvement in range with an amplifier you might gain a bit more range with more filtering.

All receivers already have a some filtering built into them. Some receivers have more filtering than others. The two receivers mostly used are the RTL dongles and the FlightFeeders.

RTL dongle has a wide open front end. This means that the receiver is actually listening to all the frequency at once and then filtered down inside the RTL chip to whatever frequency it is tuned on. The internal RTL filter is very good for the price but we have found having an external band pass filter usually increases the range under most cases. If you are using an amplifier you will see a bigger improvement. In very quiet location you will not see any improvement.

The FlightFeeders are using two different receiver boards. One receiver has more internal filtering than the other. In most cases you will see a drop in range because the internal filters are already doing their job and you are adding in the 1.5dB insertion loss of the external filter. Most likely you need to be in a noisy location for the external filter to help.

So the question is does my system need the extra filtering?
I can't really say because of the variables involved. It most cases the RTL dongle will get a marginal improvement (10% more range is probably). More range increased in noisy locations. Less range increased in quiet locations.

How do you know if the filtering is working?
Check the range before the filter and after.

Where do I put in the filter?
It doesn't matter where you install the filter. It can be close to the antenna or close to the receiver and it will do the same filtering.

Which direction do I put the filter?
Their is no front or back to the filter. It can be placed in any direction.

I am using an amplifier where do I put the filter?
Low noise amplifiers have less than 2dB insertion loss. These amplifier should go before the filter to maintain the low noise of the system.
Most normal amplifiers have a ~6dB insertion loss. Adding the filter before or after the amplifier doesn't change the noise characterisitcs of the system.

The filter doesn't seem to do anything or lowers my range?
Congratulations, you found your location is quiet. Filtering nothing and you still have nothing.
This is a filter and not an amplifier.


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 1:58 pm 
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plumley1 - FlightAware user avatar

Joined: Sat Oct 22, 2005 12:00 pm
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I will try just to see if I can improve some. I live in a suburb of a city with a Cell tower nearby. So I will give it a whirl.

Ordered and seems to be out of stock a little probably due to popularity.

Estimated delivery: Aug. 26, 2015 via Prime


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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Mon Aug 17, 2015 2:39 pm 
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tjowen - FlightAware user avatar

Joined: Mon Mar 09, 2015 11:17 am
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Filters are also available on eBay. http://www.ebay.com/itm/141748987047


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 2:44 pm 
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dbaker - FlightAware user avatar

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Yes, worldwide shipping now available on eBay, $24.99: http://rover.ebay.com/rover/1/711-53200 ... =824&kw=lg


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 5:03 pm 
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dstreufe - FlightAware user avatar

Joined: Sun Sep 18, 2005 11:00 pm
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So this filter works for 978 as well?


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 5:05 pm 
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dbaker - FlightAware user avatar

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dstreufe wrote:
So this filter works for 978 as well?


It passes 980-1150MHz officially, but a few MHz on either side would let it work....but no guarantees.


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 7:36 pm 
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Does this require a power supply? If not, will it be hurt if there's power on the cable (for a satellite amp)?


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 8:24 pm 
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dbaker - FlightAware user avatar

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jepolch wrote:
Does this require a power supply? If not, will it be hurt if there's power on the cable (for a satellite amp)?


It doesn't require power and I don't think it matters if there is power on the line.


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Mon Aug 17, 2015 8:25 pm 
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k6rtm - FlightAware user avatar

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Glad to see it's available!

I've one on order. I'll post bandpass data when it gets here -- unless you guys do it before then (which would be nice).

bob k6rtm


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Tue Aug 18, 2015 5:36 am 
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PeterHR - FlightAware user avatar

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For most people with the PiAware type feeders, the most convenient place to put this is by the dongle (would need an SMA - MCX pigtail)

If you have a power injector + masthead amp, it goes between the power injector and the dongle ... no need to be concerned about DC up the wire ... it makes no difference

------

Well done FA making this available, now all we need is:
* a similar sealed container with a PSA4-5043+ based amplifier inside for mast head use (for powering up the line)
* a power injector for use with the amplifier (the amplifier needs 3.3 - 5v @ 33mA - so this could be from USB source)

Then we'd have
Antenna
FA Amp
down-lead
FA power injector
FA filter
Pigtail
Dongle
Pi


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Tue Aug 18, 2015 4:42 pm 
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k6rtm - FlightAware user avatar

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PeterHR wrote:
For most people with the PiAware type feeders, the most convenient place to put this is by the dongle (would need an SMA - MCX pigtail)

If you have a power injector + masthead amp, it goes between the power injector and the dongle ... no need to be concerned about DC up the wire ... it makes no difference

------

Well done FA making this available, now all we need is:
* a similar sealed container with a PSA4-5043+ based amplifier inside for mast head use (for powering up the line)
* a power injector for use with the amplifier (the amplifier needs 3.3 - 5v @ 33mA - so this could be from USB source)

Then we'd have
Antenna
FA Amp
down-lead
FA power injector
FA filter
Pigtail
Dongle
Pi

Peter--

I must respectfully disagree on the ordering.

In many circumstances, filtering is needed before the LNA (amplifier stage), otherwise the LNA will be driven into saturation and will be doing more harm than good. My buddy in So Cal is a good example, with a very large very bristly cell tower a few hundred meters away. At home I have cell towers less than a km away. I run a Mini Circuits SHP-1000 between the antenna feed and the LNA, and clean that up with a SAW. Without the high pass, my LNA (Mini Circuits overkill, ZRL-2300, which has plenty of gain at 1 GHz and high dynamic range) does all sorts of nasty things. Sent my buddy a NHP-1000 and it helps, but I need to send him the gain stage that follows it.

I still think the ideal is a high pass with a very sharp cutoff and low insertion loss -- SHP-1000 or better, as most folks with problems have cell sites in the 800 - 950 range nearby. The cutoff above 1100 doesn't have to be as drastic in terms of dB/octave, as there isn't that much going on until 1800 or so, permitting the use of a less aggressive low pass element, which helps keep insertion loss down. Follow that with the LNA stage (18 - 20dB), a SAW for the narrow band cleanup, and possibly another LNA with around 10dB gain.

The proper filter configuration at the LNA input can provide static/charge protection to the LNA as well. The "protection" in our little SDRs is a pair of diodes. Yes, they provide protection against static buildup, BUT, with a strong enough signal, they conduct (in a manner known in engineering circles as being nonlinear as hell), and become a mixer, throwing all sorts of stuff into the SDR. Another reason to keep from overloading the SDR.

(looking forward to having more than a sporadic few minutes at a time to spend on this stuff again!)

bob k6rtm


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Tue Aug 18, 2015 4:57 pm 
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k6rtm - FlightAware user avatar

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k6rtm wrote:
Glad to see it's available!

I've one on order. I'll post bandpass data when it gets here -- unless you guys do it before then (which would be nice).

bob k6rtm

Bouquets and brickbats--

Looking forward to the filter! Thanks for making this available at such a reasonable price!

While the Amazon page has some response plots, I don't like them. The -3dB point should be measured from the bandpass filter center. This is about -1.5dB, the insertion loss. The bandpass corners are -3dB from that point, the insertion loss, or around -4.5dB, not the -3dB points chosen and shown.

A simple thought experiment -- if the filter had an insertion loss of 8dB, would you look for points that were at -3dB? Nope, because you wouldn't find any, at leas not near the bandpass center. You'd look for the -11dB points, 3dB down from the (insertion loss) center frequency.

In remarks to Peter, I posited that a bandpass filter for ADS-B use doesn't need as steep a low-pass skirt above 1100 MHz, as there isn't much commercial stuff (now at least) until we get to around 1800 MHz. I've got a book around here somewhere (in storage in the garage?) that talks about bandpass filters with asymmetrical response. Yeah, ask most folks to design such a beast and they will probably throw things at you until you go away. You can do it as the convolution of separate high pass and low pass sections. The relaxed low-pass skirt should result in a lower insertion loss (my gut is telling me -- although it just might want lunch, and it was a while since I did that stuff in detail)...

bob (disappearing back into the woodwork again)


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Wed Aug 19, 2015 1:28 am 
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PeterHR - FlightAware user avatar

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HABamp put's the filter after the LNA - perhaps try both before and after - see what works best.

Before if your cell tower would saturate the LNA

After if you do have a cell tower problem, it doesm't saturate the LNA and you don't want to reduce the signal into the LNA by putting the filter first.


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Thu Aug 20, 2015 4:08 am 
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spatieman - FlightAware user avatar

Joined: Tue Jan 13, 2015 4:29 pm
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i wish it was F connector, my whole rig is F-con based, but i cant have it all, think i get one, to many cell towers here grrr.


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 Post subject: Re: FlightAware ADS-B filters now for sale worldwide
PostPosted: Thu Aug 20, 2015 6:23 am 
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PeterHR - FlightAware user avatar

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spatieman wrote:
i wish it was F connector, my whole rig is F-con based, but i cant have it all, think i get one, to many cell towers here grrr.


Likewise:

Most PiAware users are not radio amateurs, the whole set up runs using a cheap computer, a cheap dongle (which has a 75 Ohm input), uses a 75 Ohm downlead and possibly 75 Ohm satellite amplifier and a 75 Ohm power injector all connected with 'F' connectors.

Maybe there should a second item on the filter sales site that includes SMA - 'F' adaptors. (M - F and F - M)


Last edited by PeterHR on Thu Aug 20, 2015 8:12 am, edited 2 times in total.

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 Post subject: Re: FlightAware ADS-B filters now for sale in the US
PostPosted: Thu Aug 20, 2015 6:59 am 
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dbaker - FlightAware user avatar

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strmchaasr wrote:
now says out of stock till the 21st


They're showing back in stock today.


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