[Ronja] Vacuum tube in Ronja preamplifier

[Gullik Webjorn]

Clock,


>From the Ronja specifications

Power out 17mW
Divergence: 1.9 mRad

Assume: 130 mm lupe, 1400m distance

If I calculate received power from this, I get

Spot size = tan(1.9e-3) * 1400 m = 2.66 m

Receive lens = 0.065^2 * PI = 0.0132 m2

Rec power = 0.017 W * 0.0132/(2.66)^2 = 31 uW = -45 dBW = -15 dBm

To me this seems like a lot of power, more than 10-15 dB above
what is specified for Fiber Optic receivers.

I guess you have allowed for fade margin, but, is Ronja really noise
limited?

Do you agree with my calculations, or did I miss something?

Regards,

Gullik