--- In [email protected], FRANCIS CARCIA <[EMAIL PROTECTED]> wrote: > > I was just telling a lowfer friend about your radio also. he is part 5 on 137 KHz. > > i2phd <[EMAIL PROTECTED]> wrote: --- In [email protected], "Phil Covington" <p.covington@> > wrote: > > > > Since the actual DSP is done in the PC, RX bandwidths less than 25 Hz > > are possible. When I quoted 33 MHz to 1 kHz bandwidth I was stating > > the I/Q data rate to the PC (similar to soundcard sampling rate). The > > encode clock (whether 67 MHz or 133 MHz) is decimated to a much lower > > rate within the on board FPGA and/or AD6620 DDC co-processors. This > > rate can be as low as 1 kHz (or less) to the PC. > > > > Phil N8VB > > > > Phil, > > quite interesting, and congratulations for this new achievement. Is > the 100 kHz lower frequency limit dictated by some constraints, or > would it be possible to go down to e.g. 500 Hz, as the SDR-IQ does ? > That would be quite interesting both for ELF/VLF/LF reception and for > other uses, like bat detectors, etc. > > And, have you fixed any tentative price range yet ? > > 73 Alberto I2PHD
Alberto, The lower frequency limit is determined by the Minicircuits T1-6T RF transformer in the front end. Theoretically it should be good down to about 15 kHz, but I wanted to err on the side of caution by stating 100 kHz. The SDR-IQ uses an active PGA/ADC driver that sacrifices noise for lower frequency response (almost down to DC). I would think a better solution to people who want to receive below 100 - 250 kHz would be to use Analog's 2.5 MSPS 24 bit ADC. It has very impressive dynamic range below 100 kHz bandwidths. I will post more pricing info in a few weeks. I will probably have a few different options based on the particular ADC used and how many DDC co-processors are populated. I intend to support the LTC2205/6/7 and LTC2208/9 16/14 bit parts as well as some of the Analog Devices 14 bit and 16 bit ADCs. The pricing will probably be similar to the SDR-IQ and the USRP motherboard. I am also in the process of developing the open source software that will be used with the QS1R. The application will be called QSRunner and is likely to use GTK+ for Windows and Linux GUIs. The DSP will likely use DttSP or an adaptation of it for the processing engine. 73 de Phil N8VB
