At 03:39 AM 3/6/2008, you wrote: >I've simulated the Tayloe integrator in LTSpice - sort of. I simulated >the circuit in "Part-I of SDR for the Masses" using Helmut's 74HC >library for the logic chips with the voltage controlled switch devices >forming the heart of the FET multiplexer. The switching stuff works >ok, but the simulation is so slow, and has to run so long in order to >see something at baseband; it's just not practical. > >I'm going to give it another try, this time I'll eliminate the 74HC >devices as they may be causing a lot of the slow-down. I'll replace >them with voltage pulse sources at the switch control inputs. I might >also do with some deeper optimization as well. I'm simulating in WinXP >SP2+ on a 3.2GHz Prescott with 2GB of RAM. > >Regards, David >
I have a similar setup with a circuit of my own design, it includes the quadrature generation, and from the antenna to the amplified I and Q signals. On a 2.4 MHz Pentium 4 it takes a couple seconds to simulate the first 200uS. I use a sub-circuit to emulate the actual performance of the switches so LTspice is nice and speedy. You may need to post the circuit on the LTspice group so some of the experts can figure why it's so slow for you. I had similar problems in the beginning but I forget what I did to make it speed up. Cecil K5NWA www.softrockradio.org www.qrpradio.com "Blessed are the cracked, for they shall let in the light."
