About a month or so ago (after receiving my radio) I ran some Tx tests in which I nulled the Transmit sideband image on the various bands and noted the resultant Phase and Gain settings (using both a 3586B selective level-meter and an 8568B spect. analyzer).
I don't have the numbers, but I recall that if you take the time, you can null each band's xmit sideband quite far down (although there was at least one case where the carrer was only 32 dB below the signal. Unfortunately, band-by-band nulling means that for optimal band-by-band performance you really should have settings stored away for each band, rather than one "global" setting. Fortunately, this is a s/w fix. - Jeff -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jim Lux Sent: Tuesday, December 13, 2005 11:15 AM To: Christoph - HB9AJP Cc: [email protected] Subject: Re: [Flexradio] TX Image Rejection Question At 10:43 AM 12/13/2005, Christoph - HB9AJP wrote: >Hi Jim >It is with speech: my ham friends say they hear me with S9+20 on 80m/LSB >and when listening to USB they hear my signal at abt S8. Is what they hear inverted (i.e. LSB)? Is it spectrally correct, or are there holes (for instance, if you dial in the image rejection for a single audio tone at 1kHz, then the rejection would be expected to get worse as you get higher or lower, so the image would have just highs and lows, but no mids.) Has anyone tried a good test of this out there? Create a WAV file consisting of a series of tones, run it out the SDR1000 transmitter, and look at it on some other receiver. By the way, I think the the impulse calibration will only calibrate the receive side, and, since the transmit and receive use entirely different electronics (i.e. different audio path, different chip for QSE), it's not clear that optimizing receive balance would optimize transmit balance. > When I try to adjust the image rejection with transmit rejct in the DSP > setup, I get abt 40db of rejection of the single tone. >73, Chris HB9AJP Jim _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
