Rain Loss Experiment [ HELP ]

Dear friends,

I want to calculate the rain loss for satellite communication. Anyone can tell me what are the equipments that i need to do it?

Some of friends told me that i need the following items
1-LNB
2-Dish Antenna
3-Receiver

Is there anything else i need to guarantee an accurate calculation?


Regards;

For your experiment, these equipments will be enough.

Vengateswaran said:

For your experiment, these equipments will be enough.

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Thank you so much bro Vengateswaran

And you need rain-meter?
And you's better ask some information of rain from your meteology office, such as rain cloud height etc.

As the satellite path will be compensated for rain loss, you must get into the electronic somewhere so you can actually measure the signal strength. Or somehow calibrate your receiver so you can equate "quality" indications with an exact signal strength.
Frank

chuckey said:

As the satellite path will be compensated for rain loss, you must get into the electronic somewhere so you can actually measure the signal strength. Or somehow calibrate your receiver so you can equate "quality" indications with an exact signal strength.
Frank

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Bro Frank, would you please interpret a bit more because i didn't got you.

Sincerely

What Frank is saying is you need an 'S' meter, one that measures actual received signal strength. You can not rely on 'signal quality' meters on satellite receivers because these almost all measure bit error rates (BER) rather than signal strength. There is a relationship between the two but other factors can also influence BER so it would not give you a true measure of signal loss only through rain scatter.

Brian.

betwixt said:

What Frank is saying is you need an 'S' meter, one that measures actual received signal strength. You can not rely on 'signal quality' meters on satellite receivers because these almost all measure bit error rates (BER) rather than signal strength. There is a relationship between the two but other factors can also influence BER so it would not give you a true measure of signal loss only through rain scatter.

Brian.

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Thanks Brian,
I will use a satellite beacon receiver, so do you think the S-meter will be provided in that type of receivers?

Sincerely

As far as I know, satellite beacons use narrow band FSK so the carrier level is constant at point of transmission. That means you should be OK to use the S-meter. Just for my curiosity, which satellite(s) are you using and how did you find their beacon frequencies. Although it isn't secret, the beacon frequencies are not usually announced, it took me a long time to find the ones for satellites visible from my location.

Brian.

betwixt said:

which satellite(s) are you using and how did you find their beacon frequencies

Brian.

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Sorry Brian i didn't got you, what do you mean?

Most satellites have one or more data/channel transmitters and a single beacon transmitter. The beacon carries satellite identification and telemetry data about the state of the batteries and other vital parts. I assume when you say you are using a satellite beacon receiver, it is that signal rather than the data transmitters you refer to. Most satellite companies will tell you their user downlink frequencies but few will tell you the frequency of the beacon channel because of it's specialized use.

Brian.

The beacon transmitter on a satellite is received by the transmission dish on earth, so the dish can be accurately pointed on the basis that if the dish is receiving the maximum signal strength from the satellite, the satellite must be receiving the maximum signal strength from earth.
Frank

... also used by outside broadcast units who have to book time slots on satellite links. With so many satellites it is VERY easy to lock to the wrong one. I have a steerable dish here and can pick up about 50 different satellites! The OBU use the beacon to confirm the satellite ID and to align their uplink to it.

Brian.

The problem I can see in your questions is that you never indicated what is your frequency band of interest.
Satellite downlink frequencies from 4/6 t 12/14 and 18 GHz have already been studied for rain attenuation, and ITU Documents have presented the results of ran loss statistics over a year in most Earth locations , according to weather areas.

You can use the ITU data to CALCULATE what you need.
If you want to run an experiment to get your data, then you must specify the frequency, find satellites that carry a beacon transmitter, design and operate a small earth station.To start you can use a spectrum analyzer connected after receiving LNB to try find a stable beacon signal, then design a SDR receiver for that frequency and collect the signal power data over a year or more. You will learn about the stability of your receiver, about the effect of antenna pointing (many satellites "wander" )and other effects beyond that of rain.

Recently, frequency band around 45 GHz is of interest or satellite downlink. In Europe, a satellite with beacons at 20 and 40 GHz is to be launched soon. Building a suitable measuring station to get rain loss data would cost estimated USD 0.5 million or more.

Good luck!