I believe Joe is trying to say that traditional test methods fall short of reality when applied to direct sampling SDR receivers, and I would believe he is correct - there are too many "other factors" to be considered (and some of them are yet unknown to most of us).
73, Don W3FPR On 5/19/2012 8:57 PM, Joe Subich, W4TV wrote: >> Guess we will have to await independent testing. The Flex folks seem >> to assert they have the equivalent of more than 24 bit when dealing >> with adjacent strong signals. > Yes we will need to wait for independent testing but given relatively > wide filters (200 KHz or more), that testing can't be done with only > two signals. The tests will need to be (notched) noise power tests or > multiple tone tests that stress the *total* power handling capability > of the system. > > It is the huge increase in instantaneous peak voltage when multiple > signals are present that causes multi-channel (multiplexed) power > amplifiers to be rated for peak powers as much as 20 dB higher that > their average operating (output) power. The same problem of peak to > average power (voltage) *will* impact the absolute voltage handling > requirements of the ADC used in any DDC system. Decimation may > improve resolution but not the absolute maximum and minimum signal > levels. > > 73, > > ... Joe, W4TV > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
