AirNav RadarBox and RadarBox24.com > AirNav RadarBox and RadarBox24.com Discussion

Do I Need A Filter?

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abcd567:
Here is RF Scan at my location showing the strong Cell / Mobile GSM signals interfering with 1090 Mhz ADS-B reception.

abcd567:
Interference from mobile / cell phone signals


The Downlink (signals transmitted by Cell/Mobile Towers) are very strong and cause problem to our ADS-B receivers at 1090 Mhz.

The Uplinks (signals transmitted by phones) are comparatively weaker  and dont cause large interference.


GSM band ƒ (MHz) Uplink (MHz)
(mobile to base) Downlink (MHz)
(base to mobile) Regional deployments GSM-850 850 824.2 – 848.8 869.2 – 893.8 North America (Canada & USA)
Caribbean, Latin America E-GSM-900 900 880.0 – 915.0 925.0 – 960.0 Europe, Asia-Pacific,
Middle East and Africa
 

saihoufung:
Hi @abcd567

Here is my screenshot of the RF Range 800-1200MHz using the radarbox flight stick only.

abcd567:

--- Quote from: saihoufung on March 05, 2019, 11:08:13 PM ---Hi @abcd567

Here is my screenshot of the RF Range 800-1200MHz using the radarbox flight stick only.

--- End quote ---

You still have strong GSM900 Mhz signal. Add a filter which can remove it.

Flightaware has recently marketed a new "1090 Mhz only" filter which they claim can filter out GSM900

https://discussions.flightaware.com/t/announcing-the-new-1090-mhz-only-bandpass-filter/45287/15

.

Runway 31:
Have ordered a dark blue filter.  I already have light blue filter which is OK for North America but not so good for Europe.  There are radio masts and cell towers near where I stay in Spain so the dark blue will be great for me.  Thanks for the link

Alan

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