Post subject: Image anf IF rejection Posted: Thu Mar 23,
2006 1:24 pm
Joined: Wed Mar 08, 2006
Guys - any idea on how to measure the image
frequency and IF rejection ratio say your in band is 98MHz.
Posted: Thu Mar 23, 2006 5:05 pm
Thu Sep 25, 2003 1:19 am
Measure your desired IF signal. Apply the image frequency at the
input and then measure the image IF.
Post subject: Image anf IF RejectionPosted:
Fri Mar 24, 2006 11:18 am
Feb 17, 2006 12:07 pm
Location: London UK
specifically if the IF is 10.7MHz, then set the sig gen to 98MHz
and note a reference level immediately after the IF filter stage.
Avoid taking a level any further down the IF chain, as the presumably
FM receiver will have a nonlinear limiter.
Set the generator
frequency to 21.4 MHz above or below the 98MHz channel, eg 76.6MHz
and increase the level of the generator until it reaches the previous
level. Note the attenuator level setting difference. This is the
Image Rejection ratio in dB
Set the generator to 10.7MHz
and repeat the measurement. The attenuator difference is the IF
Post subject: Posted: Tue Apr 04, 2006 8:54 am
Joined: Wed Mar 08, 2006 8:18 am
Thank you Guys.
I dont have the attenuator so this is what I did.
the direct inject sensitivity at operating freq. and inject the
image - the difference is my ratio. same thing on 10.7MHz for IF.