Skip to main content

Popular posts from this blog

History of HPSDR Mercury and Quick Silver

History of HPSDR Mercury and Quick Silver Philip Covington, N8VB Early HPSDR and XYLO In 2005 I started a High Performance SDR (HPSDR) project which was to consist of a motherboard carrying a FPGA/USB 2.0 interface and power supply with the provision for plug in modules through 40 pin headers. I had planned a narrow band high dynamic range module based on a QSD/DDS/PCM4202 audio ADC and a wide bandwidth module based on a high speed 16 bit ADC: http://www.philcovington.com/SDR/PICS/HPSDR_FPGA_USB_Board_top1_800600.jpg http://www.philcovington.com/SDR/PICS/HPSDR_FPGA_USB_Board_top4.jpg I soon selected the LTC2208 ADC from Linear Technology. A representative from Linear Technology came across my blog ( http://pcovington.blogspot.com/ ) and offered evaluation boards and samples to support the project. At about the same time my HPSDR project came about, Phil Harman, VK6APH and Bill Tracey, KD5TFD were interested developing a sound card replacement to be used with the SD
1 comment
Read more

2323 Wilt

Post a Comment
Read more

Possible QSD/ISD Switches/ ADC Idea/Misc

QSD/ISD Switches: Here is a link the PDF data sheets of analog switches that can be investigated for use in QSD/ISD circuits: http://www.philcovington.com/HPSDR/QSD_SWITCH/ Interesting ADC: Here is a link to an interesting ADC by Analog Devices: http://www.analog.com/UploadedFiles/Data_Sheets/AD7760.pdf It is a 24 bit, 2.5 MSPS ADC. Here is the circuit idea: http://www.philcovington.com/HPSDR/TEMP_STUFF/AD7760QSD.pdf It uses 1/2 of a QSD (not quadrature sampled) to mix the frequency band of interest down to zero Hz with a bandwidth of something like 250 kHz. The IF would be offset to something like 125 kHz. The ADC samples the 1/2QSD output and results in a real data stream. A FPGA or CPLD mixes the real data stream with a complex NCO to generate a quadrature data stream which is sent over USB to the PC where the remaining processing is done. The advantage is a 1 X LO and no I/Q balance problems. One disadvantage is that your sampling rate should be 4 times the desired bandwidth
5 comments
Read more