The DDS IF is the frequency to which the RF signal is down converted before being digitized when receiving. It needs to be sufficiently away from the signal of interest because of the "DC noise" and anti-alias filter at the IF center point (also called the 0 Hz point) will interfere with reception.
-9 KHz was chosen because it is usually outside of the RX passband of dual side band modes, such as AM and FM and LSB. Unless your RX passband filter is greater than 9KHz wide. The only reason to change it would be to better center the Panadapter when running low sampling rates (like 48K), but the tradeoff is that you may have that "DC noise" in your RX passband. I routinely set the DDS IF to 4500 Hz for my FLEX-1500, but I use this rig exclusively for digital modes and don't use wide LSB (DIGL) filters when running ASFK RTTY. -Tim -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of George R Allen Sent: Saturday, June 11, 2011 1:37 AM To: [email protected] Subject: [FlexEdge] 9Khz IF I have calibrated my Flex to WWV as per instructions in the Knowledge Base. On the calibration screen, there is an IF setting of 9Khz. I can change the IF; but, why would I want to do this? ----------------------------------------------------------------------------------------------------------------------- I am finding that the F5K has capabilities that are almost beyond belief. I find that it is really a very powerful lab instrument! George K2CM _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software. _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software.
