How to get a strong signal over a long distance?

[Electro132]

Hi,

Just wondering how can a single picture travel over long distances such as 1km and not lose its accuracy? i know it involves some sort of transmitter that can bring an image across.

So in short what i know is that the distance a single image can travel is dependant on how much power is being put through.

Can you tell me how much power would i need to accurately make a single image travel up to 1 km please and what kind of transmitter is best to use?

Thanks

 

[axcdd]

Optical fibre depanding on a band has 0.2 - 1.8 dB ( typ ~ 0.34 dB) loss per 1km. The maximum distance signal sending is not only about transmitter but also about revicer.

 

[Electro132]

Optical fibre depanding on a band has 0.2 - 1.8 dB ( typ ~ 0.34 dB) loss per 1km. The maximum distance signal sending is not only about transmitter but also about revicer.

Ok, but i was referring not to fibre optics but more wireless like LD's. How much power and voltage would need to be applied for an image (worth 600 kilobytes) to be sent over a distance of 1 kilometre?

I think power has something to do with it as the more power that gets pushed through the device the more farther the image will go. For the receiver, let's just say for this experiment, the receiver can be anything (desks, wood, metal,etc.)

 

[axcdd]

Calculator says that for 850Mhz signal 1km free space loss is equall to 91 dB.
https://www.qsl.net/pa2ohh/jsffield.htm

all comes down to transmitter power, t/r antenna gain, and how much SNR u need to reconstruct bits properly.
the point is you cant calculate this without knowing the receiver characteristics.

 

[Electro132]

Calculator says that for 850Mhz signal 1km free space loss is equall to 91 dB.
https://www.qsl.net/pa2ohh/jsffield.htm

all comes down to transmitter power, t/r antenna gain, and how much SNR u need to reconstruct bits properly.
the point is you cant calculate this without knowing the receiver characteristics.

Ok lets say the receiver can receive wave signals up to 150db, what or how can we start to calculate what components are needed to achieve getting the image across to this receiver witha distance of 1 kilometre?

 

[axcdd]

ok lets assume maximum reciver sensivity is -50 dBm, lets assume that SNR to decode the message is 30 dB, adding to this 91 dB loss in freespace for 1 Km for RF=850Mhz u get:
-50dBm +30 dB +91 dB = +81dBm and thats equall to 125,89 KW Peak power.

so finally when u dont know the reciever its parameters, know signal frequncy, transmittin/reciving antena gain, modulation of the signal u really cant calculate this.

 

[Electro132]

ok lets assume maximum reciver sensivity is -50 dBm, lets assume that SNR to decode the message is 30 dB, adding to this 91 dB loss in freespace for 1 Km for RF=850Mhz u get:
-50dBm +30 dB +91 dB = +81dBm and thats equall to 125,89 KW Peak power.

so finally when u dont know the reciever its parameters, know signal frequncy, transmittin/reciving antena gain, modulation of the signal u really cant calculate this.

Ok wait, i did the calculation and it is actually +71 dbm that it equals to (-50dbm + 30 dbm + 91 dbm). What would be the power for that?

What about the transmitter? Is the calculation the same?