[MLB-WIRELESS] New submission up at Inquiry

[Tony Langdon]

> Anyhow, going from your figures, +15 - 2 + 13 = 26dBm
> 
> Now with 1W EIRP = 30 dbm, and 100mW being 20dbm, being a logarithmic 
> calculation, (and I'm not going to work it our perfectly :) 
> then 26dbm would 
> be roughly 600mW output EIRP on the TX side. now a 13db 

26 dBm = 400 mW (i.e. 1/10 of 36dBm that we know so well :) ).

> This I can't fully remember enough to comment on... but IIRC 
> you don't include 
> the recieve gain in the free space loss? can't remember 
> exactly, I could be 
> wrong...

Because it's not free space loss.  However, you must include the receive
gain for the received signal strength calculation, so it still enters the
link budget calculations.  This is why low power/high antenna gain systems
can be better than higher power/low gain (when dealing with EIRP limited
systems).  The extra antenna gain assists _both_ transmit and receive.

A couple of examples

In all cases, assume free space loss is 130dB

Examle 1 - -4dBm Tx, 40dBi antenna gain at both ends (a VERY LARGE dish!)

Rx signal = Tx + ant gain - free space loss + Rx antenna gain
= -4 +40 -130 +40
= -54dBm

Example 2 - +20dBm Tx, 16dBi antenna at both ends (note that the EIRP is
still +36dBm)

Rx signal = 20 +16 -130 +16
= -78 dBm

Example 3 - +36dBm Tx, 0dB antenna gain both ends

Rx signal = 36 +0 -130 +0
= -94dBm

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