Filter Attachment + Blue Pro Dongle. Is this recommended?

[HottubCowboy]

I am currently using a blue pro dongle+ filter attachment. Is it necessary to use the filter since the blue dongle has a built in filter? Thanks

[geckoVN]

It’s highly location dependent, so there is no universal answer.

Usually the question is asked the other way around [Should I buy … ], but as you already have it, try removing it and see what that does to your stats.

[foxhunter]

s @geckoVN already stated it depends on your setup and your environment. An additional filter can help, but not in all circumstances.
I also have the blue dongle and additional the FA filter (dark blue) between the stick and the antenna. It “feels” that i have a marginal improvement, but so far i cannot find evidences. I am able to increase the gain, but the long term values are pretty similar to the ones without filter

There’s one thread available wit lots of information to read:

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…

[foxhunter]

Additional note:

I removed my filter yesterday for testing purposes and did not reattach it so far.
From the graphs you will not identify the time i removed it.

[HottubCowboy]

Thanks for all the responses and the assistance. I am based in downtown Hong Kong not too far from HKIA but figured I would need a filter due to close proximity with other high-rises, phone antennas etc.

I have ordered a FA external antenna (currently using a magnetic one) and might test that with and without the filter once it arrives. I switched to the Blue Pro dongle yesterday (thanks to Eric Matthews) and am already seeing a huge improvement from the generic blue $7 dongle that I was using.

[foxhunter]

@HottubCowboy

I am based in downtown Hong Kong not too far from HKIA but figured I would need a filter due to close proximity with other high-rises, phone antennas etc.

This can be a reason for an additional filter. Friend of mine in the middle of Vienna has a bad reception because of such an environment

@HottubCowboy

and am already seeing a huge improvement from the generic blue $7 dongle that I was using.

As expected
A generic stick does not have a filter an LNA for the specific ADS-B frequency

[HottubCowboy]

Yes this is why I ordered the filter. Thanks again for the assist.

[Dxista]

In HK, I would suggest using the FA ‘dark blue’ filter instead of the FA ‘light blue’ one.

[abcd567]

@Dxista

In HK, I would suggest using the FA ‘dark blue’ filter

 

To remove GSM900 interference, use Dark Blue “1090 MHz Only” filter.

Announcing the new 1090 MHz only bandpass filter!

FlightAware is excited to announce the availability of a 1090 MHz-only bandpass filter for the ADS-B community outside of North America. This is something many of you have asked for. The filter we’ve offered in the past wasn’t great at blocking GSM mobile phone interference that can be found outside of North America. This new filter is an economical bandpass filter option that provides better attenuation of 950 MHz GSM. Those of you building PiAware sites in urban areas or other areas with 950 M…

[HottubCowboy]

Thanks. I might order one of these and give it a try.

Is this the right one?
https://www.moonraker.eu/adsb-filter

[abcd567]

@HottubCowboy

Is this the right one?

That is the wrong one (light blue).

This is the right one (dark blue):

FlightAware 1090 MHz ADS-B Bandpass SMA Filter

[foxhunter]

@HottubCowboy

Is this the right o

The light blue one can work, but i would invest in the new dark blue one.as abcd567 mentioned

[wiedehopf]

@abcd567

That is the wrong one (light blue).

Apparently some sellers might not have updated the image.
If you want to order with them for some reason, maybe check?

The bandpass in the description hints towards the new filter (well actually the band pass in the description somehow is narrower than even he new filter so … i wouldn’t rely on that).

[foxhunter]

The interesting fact is that the light blue shown above also has 1090Mhz printer on it’s sticker.
I can remember that the light blue was for 978 and 1090MHz combined.
Maybe an interim release from FA?

[obj]

@foxhunter

The interesting fact is that the light blue shown above also has 1090Mhz printer on it’s sticker.

Old stock or old photo; we updated the label on that filter at around the time we introduced the narrower (dark blue) filter.

[HottubCowboy]

Thanks guys. I sent them an email as this is the only store of the two that would ship to Hong Kong. Lets hope they have the right product as I have the light blue one.

[HottubCowboy]

I got this from the OFTA which is an update on the frequencies used here in HKG (Updated April 2020)

[abcd567]

@HottubCowboy
Accolrding to OFTA (Office of the Telecommunications Authority) notification you have posted, HK has GSM900. You will need Dark Blue Filter.

 

Why dont you run an RF Scan to see what Mobile Phone signals are picked by your antenna & dongle?

Guide to conduct RF Scan is given in this post:

Do I Need A Filter?