AirNav Systems Forum

AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: blacktop on November 04, 2023, 11:10:21 PM

Title: AirNav 4-port 1090 Mhz Splitter - specs?
Post by: blacktop on November 04, 2023, 11:10:21 PM

Hi all,
     So I recently pulled the trigger on RadarBox's 4-port 1090 Mhz splitter...and it arrived today. There is no documentation included with the device. It's a passive device, so there will be losses at each port. I'd like to know 2 things:
(1) What is the dB loss per port?
(2) Anyone know of an low noise inline amp with SMA connectors and proper gain specs so that I can bias-T this device to get back to 0dB (or close to 0dB) at each port?

thanks
Newt

Title: Re: AirNav 4-port 1090 Mhz Splitter - specs?
Post by: abcd567 on November 06, 2023, 12:20:39 AM

2 port output splits signal in 2 halves, so signal strength at each output port will be 1/2 of signal strength at input port. The 1/2 strength expressed in dB is -3 dB (3dB attenuation).

4 port output splits signal in 2 halves, so signal strength at each output port will be 1/4 of signal strength at input port. The 1/4 strength expressed in dB is -6 dB (6 dB attenuation).

Above loss is for a hyppothetical splitter which does NOT have internal losses. Splitters are avaoilable which have inrernal loss say about 0.2 dB (very good & costly ones) to 2 dB (modeeately good ones) to 4 dB (poor quality low cist oes).

The total attenuation per output port for a 4-way splitter will be as follows:

Attenuation of very good ones = 6 dB + 0.2 dB = 6.2 dB

Attenuation of moderately good ones = 6 dB + 2 dB = 8 dB

Attenuation of cheap poor quality ones = 6 dB + 4 dB = 10 dB


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Title: Re: AirNav 4-port 1090 Mhz Splitter - specs?
Post by: abcd567 on November 06, 2023, 12:33:29 AM

There are two good ones which I know: Both have sma connectors.

(1) RTL-SDR Blog ADS-B Triple Filtered LNA (Bias Tee Powered) (https://www.rtl-sdr.com/new-product-rtl-sdr-blog-1090-mhz-ads-b-lna/)

(2) Uptronics 1090MHz ADS-B Filtered Preamp (https://store.uputronics.com/index.php?route=product/product&product_id=50)




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Title: Re: AirNav 4-port 1090 Mhz Splitter - specs?
Post by: blacktop on November 06, 2023, 01:39:57 AM

Awesome, abcd567. That's exactly what I was looking for. It looks like the RTL-SDR Blog ADS-B Triple Filtered LNA would be a really good fit...if I could find them in stock somewhere.  Now that I know what to look for, I'll have a look around the marketplace and see what can be had with similar specs.

The 1090MHz ADS-B Filtered Preamp looks like it will leave me a couple of dB short at each port. I could probably live with that, but would like to get back as close to 0dB as possible.

I really appreciate you getting back to me with this info.

thanks!

Title: Re: AirNav 4-port 1090 Mhz Splitter - specs?
Post by: Runway 31 on November 07, 2023, 08:00:37 PM

Can I ask why you want a 4 port splitter?

Alan