Long distance IFL

Hi,

What is the best configuration for connection between iDirect Hub and Antenna for a long distance one, let say 500m to 1 km? I mean, is it using a FO converter or L-band to IF converter or any other ? I have iDirect 5IF chassis and 4.5m Suman Antenna.

Thank you

Hi Oasis Network,

Do you have recommendation for the L-band to FO converter?

Here is another possible supplier for L band fibre optic IFL link equipment:
https://www.emcore.com/fiber_optics/satellite_microwave/satellite_transport

Setting the levels at the inputs (both ways) is important.  Avoid intermdulation noise by not setting too high.  Avoid the noise floor by not setting too low.  Discuss your application with the manufacturer to determine suitability for your application and maybe seek their help with setting up levels.

Best regards, Eric

The L band (radio) signal in the coax cable is used to amplitude modulate the laser light, so there is a modulation and demodulation process.  There is essentially just a single component at each end: laser at transmit end and light sensitive transistor at receive end.  Some clever DC power AGC is needed for the laser to keep the light constant regardless of temperature and time.

Getting the L band input level correct is the key to getting satisfactory operation.

Too low and you will get too near the noise floor and your receive C/N will degrade or you will transmit wideband noise, interfering with everyone on the satellite.

Too high and you will get intermodulation noise. On the receive side this causes all the TV carriers, plus your wanted receive carriers etc on the L band to all mix up with one another. On transmit, if you radiate 2 (e.g. A and B) or more carriers you will radiate 3rd order intermod products (e.g 2A-B and 2B-A) either side which will interfere with other people.   Ideally you want to monitor your BUC output using a high loss cross-waveguide coupler and check your transmit spectrum for any spurii.

The tricky bit is probably the receive side where you may have perhaps a hundred simultaneous carriers, across the whole of L band, so that the total aggregate power far exceeds the power of your wanted tiny return link burst carriers. The problem is keeping the total aggregate power under the intermodulation limit while keeping your wanted bursts from the remote sites well above the noise floor.

You will need adjustable attenuators on tx and rx at the antenna site.

Get advice help from the manufacturer.

Best regards, Eric.

Pulse Power Measurement out of the UK makes a product called ViaLite. We saw them at Sat2010, and will be getting a demo shortly. That is the [superlative deleted by forum admin] product that we've been able to find.. don't know if it works well yet.. But intelsat uses them for most of their Teleports..

Added by forum admin: Link: RF over optic fibre by ViaLite

I was thinking about calling you actually..! Are you going to Interlink?? It's been a while since we talked, drop me a line sometime so we can catch up.. I've actually got some new things in the pipeline this year