I have been searching for some basic documentation describing the GRC components without much luck. For instance, I can't find an explanation of why multiplying with a 50ksps sine wave specified to have zero frequency and an amplitude of 1 has any effect, though I have seen it in several examples e.g. an SSB transmitter. I am using the LFRX, which has no frequency conversion capability, but the "Frequency" setting in the USRP2 block certainly has an effect. What is it doing to the LFRX hardware? How can I decimate in the USRP2 block and separately specify a frequency? If I put a constant input to a USRP2 sink, it produces a tone at the frequency specified in the block. I am not sure what is actually happening in the LFTX daughterboard in that case since it seems to be a DC input. I want to read about the Throttle block, how it works, and when it is needed. I want to understand the differences between the frequency translating FIR filter and decimation. I looked at the Doxygen documents on gnuradio.org, but those are more about describing data structures and such details. The Ettus FAQs also don't cover these issues.
Individual basic questions like these are likely inappropriate for this forum, so I would like some suggestions about places to find the answers to questions that many others must have also asked. Please direct me to something more like a user manual or some more informal collection of documents if one exists.