The Strange True Story of a Radio Station's Transmitter inNewY...
 

DLoyd wrote:
"Due to the "Inverse Square Law", it was impractical and always will
be."

How much power do you need? Does radio reach the stars? Does light from
the stars reach us by "radio" type waves?

Because the power of a radio wave declines due to distance by only 6 db
each time distance doubles, the 6 db distance can be almost infinite and
the power useable dependent on the power required and and the power of
the source.

Best regards, Richard Harrison, KB5WZI

The Strange True Story of a Radio Station's Transmitter in NewY...
 

Hi Richard

I could no doubt look this up but thought I would be lazy!

What is the link budget for deep space probes like? What is the RX level
on earth etc etc? I had always assumed a low datarate and nitrogen
cooled front ends on the ground but I dont actually know what the
numbers are...

I kind of already know the numbers for AMSAT and EME work.

If you dont know off the top of your head, I can look it up...

Cheers Bob VK2YQA




Richard Harrison wrote:
DLoyd wrote:
"Due to the "Inverse Square Law", it was impractical and always will
be."

How much power do you need? Does radio reach the stars? Does light from
the stars reach us by "radio" type waves?

Because the power of a radio wave declines due to distance by only 6 db
each time distance doubles, the 6 db distance can be almost infinite and
the power useable dependent on the power required and and the power of
the source.

Best regards, Richard Harrison, KB5WZI

The Strange True Story of a Radio Station's Transmitter inNewY...
 

Bob, VK2YQA wrote:
"What is the RX level on earth etc.?"

J.D. Kraus was a great radio astronomer. On page 403 of the 3rd. ed of
"Antennas" which Cecil touts is found eqn. 5 for the Source Flux Density
in watts per sq. mtr. per Hz bandwidth.
Kraus notes that:
"In radio astronomy observations, flux densities are very small, and the
unit of convenience is the jansky (jy) = 10 to the minus 26 W/m squared/
Hz bandwidth, after Jansky who made the first radio astronomy
observations in 1933.

I`ve worked with wide-band terrestrial microwave receivers (2 or 3 MHz
bandwidth) having sensitivities of about -90 dbm, and 2-way FM radios
having sensitivities of about 1/4 microvolt for a bandwidth of about 16
KHz. Both examples were about state of the art at the time.

I`d bet on Kraus anytime.

Best regards, Richard Harrison, KB5WZI