Hi All, We're having some problems with transmitting using the WBX board on a USRP1 (not an old one). We have a flow graph with a NULL source going into a NBFM, then through a multiply_const and into the USRP. At low frequencies (100MHz) the signal looks ok, but when we get up passed 500MHz we can see/hear that what should be an unmodulated carrier also has a single side-band (and is audible as a tone when demodulated) . And by increasing the const in the multiply_const, we can see our wanted signal getting stronger while the side-band remains there at a constant level.
We've had a play with manually adjusting the DC offset of the USRP sink, which seems to change the size of the side-band a bit, but we don't really know what to do with that. We've tried several USRPS and several WBX boards and seen the same problem on all of them. We don't see it on the USRP2. We don't see it with the flex400 board. This picture http://tinyurl.com/27w5s8n shows the side-band on the left and the wanted signal on the right. The grc file is also attached. Any help you can offer would be greatly appreciated thanks! Drew -- Andrew Read +64 (03) 357 0787 Test Analyst Design Verification and Validation Team Tait Electronics Ltd ======================================================================= This email, including any attachments, is only for the intended addressee. It is subject to copyright, is confidential and may be the subject of legal or other privilege, none of which is waived or lost by reason of this transmission. If the receiver is not the intended addressee, please accept our apologies, notify us by return, delete all copies and perform no other act on the email. Unfortunately, we cannot warrant that the email has not been altered or corrupted during transmission. =======================================================================
weird-sideband.grc
Description: Binary data
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