Hi guys, I don't know if this information is of any use to anyone, but here is what they said:
Cal, Theoretically you can monitor a 60MHz chunk of spectrum, but there are a few limitations to consider: The standard software for USRP1/USRP2 sends samples as 16bit, complex (I/Q) values. For practical purposes, this means the USRP1 can pass 8Msps over USB2 and the USRP2 can pass 25Msps over gigabit ethernet. Those figures translate directly into 8MHz and 25MHz of instantaneous spectrum access respectively. If you want to monitor a wider bandwidth, you would need to use fewer bits per sample. I believe there may be community implementations of 8bits or less per sample, and we are working on our own, but no eta. You are of course free to take the software/fpga code and do this yourself. We do not currently spec frequency switching time (LO lock time) of our daughterboards. It is likely to be substantial fractions of seconds if you need to change the LO on the daughterboard. If you are wanting to do frequency hopping, my suggestion would be to stick within a 60MHz window and then use the DDC to select smaller chunks of the 60MHz to send over the bus from USRP to Host PC. Even better would be to hop within the 8MHz or 25MHz of instantaneous bandwidth on your host pc using the analysis filter bank. Then you could have very fast switching. Jason - Hide quoted text - On Fri, Jul 23, 2010 at 12:57:06PM +0100, Cal Leeming [Simplicity Media Ltd] wrote: > Hey, > > I have been monitoring the progress of the USRP for almost 2 years now, and > have finally convinced myself to spend some money on investing in some radio > fun! > > I just wanted to confirm the following points (please excuse me if I have > used the wrong terminology!): > > > - In the DBSRX specifications, it states that the software can monitor a > channel as wide as 60mhz. Does this mean the accuracy of data or the error > probability goes higher, when you increase the channel width? And also, does > the resolution suffer greatly by monitoring a wider band? (i.e. if I was to > monitor a single 1mhz channel, and then switched to a wide 60mhz channel, > would the data be less precise?) - let me know if this question doesn't make > any sense! > > - How quickly is the USRP able to switch frequencies? (From the moment I > send a python query, to the point of the daughter board physically switching > over) > > > Cheers! > > -- > > Cal Leeming > > Operational Security & Support Team > > *Out of Hours: *+44 (07534) 971120 | *Support Tickets: * > [email protected] > *Fax: *+44 (02476) 578987 | *Email: *[email protected] > © 2010 Simplicity Media Ltd. All rights reserved. > Registered company number 7143564 -- Cal Leeming Operational Security & Support Team *Out of Hours: *+44 (07534) 971120 | *Support Tickets: * [email protected] *Fax: *+44 (02476) 578987 | *Email: *[email protected] Simplicity Media Ltd. All rights reserved. Registered company number 7143564
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