Life in the Early Universe: Origins and Evolution

[Vanadium 50]

The Aricebo message has an effective isotropic radiated power of 20 TW and a bandwidth of 5 MHz (well, that's the narrowest it goes; I don't know what they actually used). That's 4 MW/Hz.

Alpha Centauri is 4.6 times closer, so the signal would be 20x stronger, or about 100 MW/Hz equivalent. No problem to see with a sensitivity of 7.

 

[mfb]

5 MHz bandwidth?

transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz

Source
On November 16, 1974, the Arecibo Observatory transmitted at 2380 MHz at an effective bandwidth of 10 Hz a message directed at the globular cluster M13.

I think there is a good safety margin, if the receiver listens at the whole frequency band or the communication is coordinated.

10 Hz instead of 5 MHz increases the power (per frequency range) by a factor of nearly 10^6, which corresponds to an increased range of a factor of 10^3 (20000 ly instead of 20) - or a factor of 10^6 (?) in bit rate.

 

[Vanadium 50]

Yes, the width is 5 MHz. The modulation rate is 10 MHz.

 

[mfb]

Where does that number come from?
With a width of 5 MHz, I would imagine that it is hard to detect a shift of 10 Hz (not MHz!).