Attention all RF/HAM Gurus! Using the propeller for a VLF to Short Wave (or DC to 30mhz) SDR?
rwgast_logicdesign
Posts: 1,464
in Propeller 1
Ive been working with those $10 dollar real tek dongles has a hobby for about a year. I mean ive just basically learned more about how radio works how to design antennas, lna's, and analog filters.
I would love to make my own SDR for 0 to 30Mhz. I dont quite understand SDR and IQ, and know it is something I would have to learn. I guess what I am wondering is if the propeller could be used to make an SDR without some kind of front end tuning chip Obviously a prop can interface to a realtek chip or some fancy analog devices chip like the ones in the Ettus. But this is really about learning and I would think that an OCed propeller should be capable of picking up and dealing with at least a 25mhz signal.
Does anyone have any insight on this, im thinking you can use a nice ADC connected to an antenna, or even the props capability to do sigma delta. then send that to that data to the prop to run whatever algorithms SDR's run to get I and Q and then straight out the serial port to the pc?
I know this by far is not an easy project and RF isnt the easiest signals to work with, but I would like to do this to learn how an SDR works then. maybe move on to an arm with with a front end tuner if I wanted to try to make something more advanced
I would love to make my own SDR for 0 to 30Mhz. I dont quite understand SDR and IQ, and know it is something I would have to learn. I guess what I am wondering is if the propeller could be used to make an SDR without some kind of front end tuning chip Obviously a prop can interface to a realtek chip or some fancy analog devices chip like the ones in the Ettus. But this is really about learning and I would think that an OCed propeller should be capable of picking up and dealing with at least a 25mhz signal.
Does anyone have any insight on this, im thinking you can use a nice ADC connected to an antenna, or even the props capability to do sigma delta. then send that to that data to the prop to run whatever algorithms SDR's run to get I and Q and then straight out the serial port to the pc?
I know this by far is not an easy project and RF isnt the easiest signals to work with, but I would like to do this to learn how an SDR works then. maybe move on to an arm with with a front end tuner if I wanted to try to make something more advanced
Comments
http://forums.parallax.com/discussion/105674/hook-an-antenna-to-your-propeller-and-listen-to-the-radio-new-shortwave-prog/p1
-Phil
http://armradio.weaksignals.com/
Like I said I would love to do 1-20/30 mhz SDR maybe even throw a DSP in the thing with an LCD and make it portable. Something I have been thinking about though is communications bandwidth to the host PC. I tried one of those analog devices USB isolation chips on a realtek dongle only to find that that dongle operates way faster than usb full speed i.e 12mbit. SDRs like the HackRF and Ettus stuff use ARM/FPGA designs so they already have a nice high speed USB peripheral built in to there hardware.
What would be the fastest way of sending data to the PC from the prop? I know Maxim makes some usb chips but they seem to be full speed from what I can tell. The prop scope uses an FTDI chip I believe so is it only running at 12mbits or less?
win exe + source code
https://sites.google.com/site/swljo30tb/home/files
What would be the fastest way of sending data to the PC from the prop? I know Maxim makes some usb chips but they seem to be full speed from what I can tell. The prop scope uses an FTDI chip I believe so is it only running at 12mbits or less?
12 Mbit/s is full-speed, and is available from FTDI chips. High-speed (480 Mb/s) FTDI chips are available but the Propeller wouldn't be able to keep up with 480 Mbit/s. Some ARM chips have high-speed USB interfaces and XMOS chips can handle it in software.
Reinhard, thank you ill look in to that when I get some time... off to build a crossover system for someone, and my toddler wont stop climbing on me
Does anyone have any insight on this, im thinking you can use a nice ADC connected to an antenna, or even the props capability to do sigma delta. then send that to that data to the prop to run whatever algorithms SDR's run to get I and Q and then straight out the serial port to the pc?
I would expect direct ADC connect would need a serious ADC and serious crunching power, better may be to get to a lower IF first and then process a more manageable
frequency.
Some quite good Synthesis chips are around, like Si5351A, just over $1, which can to 2.5kHz to 200MHz, which could clock a dual-D-FF and Mixer to get I & Q signals
A front end Band-Pass and IF band-pass would give better/simpler rejection than a direct ADC can offer.
I've also tested a Si504 which has the appeal it is set with a 4 byte float, but SiLabs have just EOL'd the Si504 series - so not a good long-term choice.
At a glance, google finds AD8333 (maybe ADL5387 or AD8348) and LT5517 as candidates for the IQ demod