Software Defined Radio Vlog - Part 2

Part 2 - I show the progress of a homebew Software Defined Radio(SDR) or Direct Conversion receiver (DC). IQ signals now being generated correctly, but harmonics picked up from electronics.

Complete project details will be available in the upcomming video for element14 http://www.youtube.com/user/jeriellsworth

Category:

People & Blogs

Tags:

• Software defined radio
• SDR
• DC reciever
• Jeri Ellsworth
• FPGA
• electronics
• ham
• radio
• sortwave

[rogercritchlow]

Very nice progress since the last video.

Someone commented that running the LO through the FPGA -- I think he meant as in implementing the I/Q divider flipflops in the FPGA -- would make a bunch of phase noise. Are flip-flops in programmable logic necessarily phase noisy, or does it depend on how they get laid out?

[JeriEllsworthJabber]

@rogercritchlow I'm not currently using the FPGA for clock phases. It would not be a problem to constrain the FPGA to control the phase between each output.

[whydontyoublogabouti]

@rogercritchlow I'm working with an SDR design at the moment and have tried using the Spartan-3A DCM to synthesise LO frequencies and because it's a delay locked loop, it has awful phase noise. The Spartan-6 has PLLs, which may be better. I've since gone all the way and am using a DDS, driven by an OCXO, and will be steering that using a GPS-derived 1pps signal (overkill for one SDR, but handy if a network of independent receivers need to be perfectly synchronised in frequency and phase)

[JeriEllsworthJabber]

@whydontyoublogabouti Very nice!

[tagno25]

Will you add a TX function, or just leave it RX only?

[JeriEllsworthJabber]

@tagno25 RX for now. I won't have time before the Element14 video is due. I'll come back someday and make a transmitter the same way.

[gccengineering1996]

I need a SDR receiver and want to learn on how to build one. I need something that would cover 1 kHz to 30 MHz.

[Soupie62]

I'm researching SDR on Yahoo - this looks good!

My own idea is / was to hack a DSO203 prtable 'scope... convert IF using tha fast ADC, then re-program the built in FPGA. Sound goes to PC via USB connector.

[sparkyrocky12131963]

your work bench is a mess LOL.

but you are definately a good tech.

bravo with those SD boards sincerely

KC9RSV.

[sparkyrocky12131963]

your work bench is a mess LOL.

but you are definately a good tech.

bravo with those SD boards sincerely

KC9RSV.

[tpulley]

I didn't know about WinRad prior to seeing your videos. Having visited their site I noticed that there are newer versions. Is there any particular reason you're using 1.33 instead of a newer one?

[thewii552]

you have a really big laptop...