Re: RF Budget Analysis
Actually, there are two RF budget analsis:
a) RF "link" budget and
b) RF chain budget.
In a) the intention is to design a link which comply with
the specifications. That is, design for a maximum error
at the maximum distance. It is done based on "average"
received power. It takes values as transmitter output power
(Po), Antennas Gains(Transmitting and receiving), Receiver
sensitivity and characteristics of the channel(Rayleigh, Rice,
Log-Normal, Nakagami, etc). The link budget add or substract
the values (Po, Gr, Gt, Free Space Loss, Fading, etc) and check
if the sensitivity (or S/N) is accomplished.
If not, the designer must increase the gain or power or decrease
the distance.
In b) the intention is almost the same. For a given minimum
power at the input of the receiver the designer should check
if the receiver has the maximum error allowed. It takes values
as Gain, Losses, Noise Figure and Distortion along the receiver
chain to calculate the sensitivity(or the minimum S/N). The goal
here is minimize the sensitivity( ex. -80 dBm) at the maximum
error allowed (ex. 10^-3)
In a) the analisys is external to the receiver and in b) the analysis
is basically internal to the receiver.