FlightAware Discussions

Antenna RF-to-Fibre cable runs?

Hi all,

I searched the forums and did not see anything on this topic - but please pardon me if this has already been answered.

I work for a company in the aviation industry, and we are interested in putting a 1090 MHz antenna on top of our office building (14 stories high). Has anyone put together a system which uses an RF-to-Fibre converter between the antenna and their PiAware Receiver?

The reason why we are looking at this is that we only occupy the lower floors of this building, and would otherwise be forced to make a long coax cable run, which for various reasons is not feasible. However, there is a loom of fibre already in place which goes from the top floor of the building down to our floors.

Any experience anyone might have would be greatly appreciated.

Best regards,
Ed

Fibre can replace the ethernet but not the RF coax.

Not used this company for this application, however we use some of their products for live events broadcasting.

You will require an LNA before the converter unit unless there is already one included in their product.
We use just the bare converter with our design of LNA and BDC.

https://www.vialite.com

Not cheap.

Can you relay off another location with Ubiquiti WiFI?
https://linitx.com

I work with RF over fibre systems but I don’t think an RF over fibre system is what you want (or expect could afford). In an RF over fibre system you convert from RF to light, transmit it over fibre and then convert it back to RF. This means you have to have your RF to fibre receiver at the antenna and those receivers are very expensive compared to a raspberry pi. I think you would be better off putting a waterproofed Raspberry pi system on the roof next to the antenna and then use the fibre via a suitable Ethernet to fibre adapter to bring the Ethernet down to your floor.

Thanks Lawrence - we can spend some money to get this done; do you have a rough order of magnitude cost? I see items like this for example: L-band over fiber, RF Fiber tx rx, l band satellite extender, DTH over fiber

ed

Also to be clear, the issue is getting network connectivity to the roof. One of the issues in this building is that it is pretty opaque to RF - we needed to install interior cell repeaters to an external antenna to get any cell coverage in the building.

In some testing in my office, with the antenna inside next to a window, I was getting about 5-10 targets at a time, max. Moving the antenna outside to a patio upped that to over a hundred - but we’d be blocked from half the sky. We certainly could also fall back to putting it outside our offices closer to the ground, but we want to chase down whether a roof installation is possible…

The problem with that device is that it is designed to operate with a satellite LNA. It will be working with a high level signal and it will have a very poor noise figure. This will not matter in its intended application as the noise figure will be determined by the LNA front end and this device will be in the IF frequency. You asked about rough order of magnitude costs I would think you are an order of magnitude out with something like that. I would estimate about €30,000 for something with the right specifications but as I say I don’t think it is the correct solution. What I believe you need is to put your receiver on the roof with the antenna and then use an industrial Ethernet switch that is rated for outside use that will convert your Ethernet from Cat 5 to optical fibre for transmission to your office.

If you have access to power at the roof, it might be simplest to just install the pi and receiver in a waterproof box there. It may be possible to use the fibre to get network data to it, but it probably won’t be cheap for a fibre network adapter that the pi can use.

Perhaps using a 4g data connection to it would be a viable option. The data demands aren’t too onerous if you are selective about where you send the data.

Thanks guys - I appreciate the alternatives. I will bring these back to the group working this.

These should be a lot cheaper than 30,000€
The 1GHz version is about £600-700 each end.

https://www.vialite.com/wp-content/uploads/2020/04/ViaLiteHD-Yellow-OEM-Link-Datasheet-HRx-xx-xN-DS-2.pdf

However, as previously mentioned, you will need an LNA.

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