SDR (Software Defined Radio) Transceiver

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Matony
Posts: 5
Joined: Wed Aug 06, 2014 6:44 am

Re: SDR (Software Defined Radio) Transceiver

Post by Matony » Sun Feb 08, 2015 11:12 am

Nils, look at http://gqrx.dk/. What are the current possibilities for network streaming with red pitaya ? Digital Down Converter (DDC) may be used ? Thanks ;)

Nils Roos
Posts: 1441
Joined: Sat Jun 07, 2014 12:49 pm
Location: Königswinter

Re: SDR (Software Defined Radio) Transceiver

Post by Nils Roos » Mon Feb 09, 2015 8:30 pm

@Matony
It will take me a while to find out how the Red Pitaya could fit in there.

@piccolo
Sent you an email.

mrzfrn
Posts: 2
Joined: Sun Feb 01, 2015 9:34 pm

Re: SDR (Software Defined Radio) Transceiver

Post by mrzfrn » Mon Feb 16, 2015 4:33 pm

http://www.box73.de/download/zeitschriften/015-02.pdf
Funkamateur 2015-2 pag 158-165 (German magazine)
-SSB-Sendessignalaufbereitung mit dem Red Pitaya
Can some body read it and make a "resumé" (English!), just the key points ?
Can this paper be available free to Red Pitaya forum registered users ?

pavel-demin
Posts: 33
Joined: Tue Dec 23, 2014 10:52 pm

Re: SDR (Software Defined Radio) Transceiver

Post by pavel-demin » Wed Feb 18, 2015 1:16 pm

Hi,

I've developed a SDR receiver with I/Q demodulator and filters running directly on the FPGA. The I/Q data stream is transmitted via IP multicast to the SDR programs such as SDR# and HDSDR.

With a basic loop antenna I can receive some broadcast stations. Strong stations sound very good.

I would be very interested to know if somebody could test this SDR receiver with a good antenna and post the results.

You can find more information about this SDR receiver together with a bootable SD image and a plug-in for SDR# and HDSDR at

http://pavel-demin.github.io/red-pitaya ... -receiver/

Cheers,

Pavel

mrzfrn
Posts: 2
Joined: Sun Feb 01, 2015 9:34 pm

Re: SDR (Software Defined Radio) Transceiver

Post by mrzfrn » Fri Feb 20, 2015 10:39 am

Very cool !
Add Downconverter FM2SW NTi FMC 108-28 ( http://www.nti-online.de/eFMC%20108-28.htm) and you can decode well FM87.5-108.
Or use undersampling . Instead of low pass filtering ( 1 Nyquist zone 0-60 MHz) ) put band pass filtering of 2 Nyquist zone ( 60-120) .
Some tickering at input is in order. Is that possible ? Schematic of analog input badly needed!

At web site http://www.sdr-j.tk/index.html you find a lot of open source Linux SDR software
well tested (even DAB+ decoder , but Nyquist zone 4 , perhaps not doable by RP).

Altair
Posts: 4
Joined: Fri May 08, 2015 1:40 pm

Re: SDR (Software Defined Radio) Transceiver

Post by Altair » Fri May 08, 2015 1:44 pm

I've measured sensitivity of Red Pitaya in SDR role. I got only 10 uV...
I didn't use special tool for measuring SNR, but i have enough experience for approximately estimation it.

pavel-demin
Posts: 33
Joined: Tue Dec 23, 2014 10:52 pm

Re: SDR (Software Defined Radio) Transceiver

Post by pavel-demin » Fri May 08, 2015 9:07 pm

Thanks a lot for this measurement!

I'd say that 10 uV over 2 V is not far from the maximum performance that we could expect from the Red Pitaya board.

The effective number of bits of the ADC is not better than 12 bits, then we get 4-5.5 additional bits from the decimation. If I'm not mistaken 10 uV over 2 V corresponds to 17.5 usable bits.

At what rate (50, 100, 250 or 500 kSPS) do you obtain this result?

Kind regards,

Pavel

Altair
Posts: 4
Joined: Fri May 08, 2015 1:40 pm

Re: SDR (Software Defined Radio) Transceiver

Post by Altair » Sun May 10, 2015 5:24 pm

The sample rate was 100 kSps.
I've got a bit ugly, self maid LNA based on GALI74+ with LPF on 2 MHz
I can try to connect it to the RedPitaya and make test again, now with nonlinear distortion meter. My ears are beautiful, but they aren't measurements tool :-)
LNA have 20 dB amplification - i measured it by the Spectrum Analyzer.

About sensitivity.
I saw signal on the waterfall with smaller input, but i meant receiver sensitivity with SNR 10 dB.

Yuri

N4TLF
Posts: 7
Joined: Fri May 29, 2015 1:39 am

Re: SDR (Software Defined Radio) Transceiver

Post by N4TLF » Fri May 29, 2015 2:05 am

Hello Pavel and others!
A friend and I just received our Red Pitaya boards, and are trying to set them up as SDRs. While I've been able to run the Red Pitaya apps, I'm having a hard time getting the Red Pitaya to work as an SDR. I know that either I'm doing something stupid, or I'm missing something.

Firstly, I cannot find the SD card image file for the SDR app. I've looked all over this page for the link to the image, no luck:
http://pavel-demin.github.io/red-pitaya ... -receiver/

I've also tried to follow the instructions to add the two files to a clean version of the current ecosystem (Ecosystem (0.92-65)), as described on the above page, under "Getting Started". Again, no luck. If I ssh into the Red Pitaya after booting it from that card, I can see the original /dev/xdevcfg file, plus a file named /dev/xdevcfg? (with a question mark at the end of the name). I'm assuming that's the main problem I am having, the old xdevcfg is not being overwritten, and the new version is named wrong, and therefore not found.

As an aside, I added the two lines to the Windows/Fat32 version of /etc/init.d/rcS, not the /etc/init.d/rcS in Linux after the RP boots.

I'm a ham (N4TLF, ex WB4JFI), and have been playing with various SDRs for several years now, from SoftRocks to SDR-IQ, homeuilt HiQSDR, and a Flex-6500. I want to do more with FPGAs, I've messed with Digilent Nexys2 and a "Charleston" SDR board. I'm most familiar with Windows, but have been using Linux off and on since it came out.

The RP looks like it has real potential, especially if one hooks a decent PGA or other preamp, and filtering in front of it. If I can get the RP SDR going, I'll probably buy a second one.

Thank you guys for any help you can provide!
Terry, N4TLF

pavel
Posts: 618
Joined: Sat May 23, 2015 5:22 pm

Re: SDR (Software Defined Radio) Transceiver

Post by pavel » Fri May 29, 2015 7:57 am

Hi Terry,

Thanks for your interest in my SDR project!
Firstly, I cannot find the SD card image file for the SDR app.
Initially, I had to build an SD card image for the very first version of the SDR. Then I found a way to make the FPGA configuration for the SDR compatible with the original Red Pitaya SD card.

Current version works with the ecosystem SD card and it should be installed as described in the "Getting started" section.
As an aside, I added the two lines to the Windows/Fat32 version of /etc/init.d/rcS
This is correct.

I've just managed to reproduce your problem. I edited the rcS with an editor that changed the end-of-line characters in this file from UNIX format (LF) to Windows format (CR LF). Then I indeed obtained two /dev/xdevcfg files with the following error messages on the Red Pitaya console:

Code: Select all

: not found/rcS: /opt/etc/init.d/rcS: line 16:
: not found/rcS: /opt/etc/init.d/rcS: line 18:
Could you try to either convert the rcS file back to UNIX format or edit the original rcS file with an editor that respects the end-of-line characters?

For conversion, there is a program called dos2unix:

http://waterlan.home.xs4all.nl/dos2unix.html

For editing, notepad++ works very well:

https://notepad-plus-plus.org

Kind regards,

Pavel

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