Question on RX structure

some paper suggests a structure for RX,
RF signal from antenna is fed to a up-mixer and then a second down-mixer, followed by filter and AGC
I wonder what is the merit of this structure?
why is the signal first up-converted and then down-converted?

thank you.

Possibilities include

1-Image Rejection
2-Ease of filter design
3-VCO Tuning Bandwidth


Dave
www.keystoneradio.com

i think the both mixers are downconverters , and this is called superhetrodyne architecture ,

check ur info again

khouly

maybe I need a more detailed explanation....
one application of this structure is for wide band, e.g. dvb-t.

Added after 5 minutes:

up-conv and then down-conv, definitely.