ADAR1000 - Receive section GAIN in RevB datasheet

Single Channel and Coherent Gains are correct.  Electronic Gain as stated is not correct. 

You can define Electronic gain as the output power/sum of the input powers.   So it is basically measured the same way as coherent gain, but instead of being referenced to a single inputs' power, it is the sum of the input powers.   So if you have 0 dBm (1 mW) on each input, across four inputs, that is 4 mW sum.  If the output is at 19 dBm (79.5 mW), then the electronic gain is:

• 10*log10(79.5 / 4) = 13 dB

Coherent gain would be:

• 10*log10(79.5 / 1) = 19 dB

I am assuming the signals are the same amplitude when applied to the combiner and in-phase with each other. 

By the way, these input powers would push the receive well into its compression, so they are not realistic.  The above analysis assumes that the compression isn't happening.  

Single Channel and Coherent Gains are correct.  Electronic Gain as stated is not correct. 

You can define Electronic gain as the output power/sum of the input powers.   So it is basically measured the same way as coherent gain, but instead of being referenced to a single inputs' power, it is the sum of the input powers.   So if you have 0 dBm (1 mW) on each input, across four inputs, that is 4 mW sum.  If the output is at 19 dBm (79.5 mW), then the electronic gain is:

• 10*log10(79.5 / 4) = 13 dB

Coherent gain would be:

• 10*log10(79.5 / 1) = 19 dB

I am assuming the signals are the same amplitude when applied to the combiner and in-phase with each other. 

By the way, these input powers would push the receive well into its compression, so they are not realistic.  The above analysis assumes that the compression isn't happening.