How alfa will handle rfi

Filtering:

Waveguide cutoff (1125) will remove cellular band (see lbw dewar).
Bandpass filter 1225 to 1525. filter out satellite band 1550 and above.

Headroom in the system:

Location	power level Dbm	1 db compression	headRoom db
Dewar Output (30K Tsys,300Mhz)	-58	+5	63
Fiber Input	-25	+10 (melts??)	35
Downstairs Amps	-9 ?	+ 13	22
Digitizer 12 bit (3bits Tsys-->9bit)			66 (54)
Digitizer 8 bit (3bits Tsys --> 5bit)			42 (30)

(Further discussion)
The san juan radar has a good chance of saturating the downstairs amps and probably the digitizer (but... estimating pulsed power levels with a spectrum analyzer is probably not the smartest way of doing it).

Harmonics created in the IF (downstairs amps):

The current system has harmonics of radars created in the 2nd IF.

Placing the radar 130 Mhz below the 260 Mhz IF creates harmonics (the birdies 1330 to 1340 are caused by the 8bit digitizer) (further discussion)

ALFA harmonics created in the IF depends on the lo.

next previous