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RadioBox - the radio amateur's toolkit for RF

Posted: Mon Oct 26, 2015 12:57 am

a new project is born at the sky of Red Pitaya: an application called RadioBox that includes facilties for
transmitting and receiving radio signals.

The main idea behind this contributed application to the Red Pitaya ecosystem is to use the FPGA to create
blocks for doing modulation, filtering, FFT and so on by its own, without the big help of an external processor.

At the moment (2015-10-26) there are two DDS oscillators, one modulating the other, giving frequency modulation
(FM) and phase modulation (PM). Additionally an output mixer enables for amplitude modulation (AM), also.

It is in my interrest to expand for single-side-modulation (SSB) and to include filters for signal forming and noise

Thinking more ahead: automatic data encoders and decoders would give new possibilities to design own data
transfer variants. For getting that into action I will include (R)-FFT blocks for these enhanced modulation modes.

I am very exited to have a new "winter project" to beat against the November blues, yeah! :P

@see here for the short introduction about the facilities included in RadioBox so far:

@see here for the GitHub account:

@see here for pre-compiled binaries to put on an ecosystem-0.94 - some pictures are included here, also: ... j3R1a?dl=0


Feel free to test this (mini) application that growth rapidly. :D

Vy 73

PS: sorry for cross-posting, I have seen this folder to late for making up my mind.

Re: RadioBox - the radio amateur's toolkit for RF

Posted: Mon Oct 26, 2015 1:19 pm
by pavel
Hi Uli,

I'm very impressed with the road map of your project!

Do you think that it would be possible to fit all the radio related processing blocks and the Red Pitaya ecosystem into the same FPGA configuration?

Looking at this commit and especially at the
to rebuild your FPGA sources to work with Vivado2015.2 again, the way as Xilinx does explain in their tutorials
part, I'd like to point out that the Tcl based design flow is a perfectly valid design flow supported by Xilinx and explained in the following Xilinx tutorials: ... ado-ip.pdf ... ipting.pdf ... torial.pdf ... erview.htm

I agree that the advantages of using Tcl scripts to build the FPGA configuration bitsream files are not obvious. However, Tcl scripts simplify things really a lot for the next steps when one needs to build u-boot, boot.bin and devicetree.dtb. It also simplifies migration from one Vivado version to another.



Re: RadioBox - the radio amateur's toolkit for RF

Posted: Mon Nov 02, 2015 9:07 pm
by Bulova
Hello Uli,

I am interested in your RadioBox project. I am not a programmer, so is it easy to use your APP anyway? The files -- do I have simply to add these in the repository of all the others in the Eco system? Or what elso do I have to do?

Thanks in advance.


Re: RadioBox - the radio amateur's toolkit for RF

Posted: Sun Nov 08, 2015 12:06 am
Exactly, that is how it works. Simply add the new radiobox folder to the ecosystem application folder.
I have it running with ecosystem 0.94-396. Your requests are welcome.

Current status: the RF Input 1 and RF Input 2 are enabled for the signal modulator (AM, FM, PM) since today.

Sorry for the delay, many time I have invested to get a double precision value transfer between the web front-end
and the back-end running. Now, you can enter frequenies, modulation grades, amplification values in decimal
with 16 digits accuracy.

Due to the 48 bit DDS Oscillators, the minimal frequency as well as a frequency step is abt. 444 µHz small.

Vy 73
Uli, DF4IAH 8-)

Re: RadioBox - the radio amateur's toolkit for RF

Posted: Mon Nov 09, 2015 9:58 pm
by fisafisa
Now having the ability to switch to an external clock with good precision and stability would be good.
Can this be done?

Re: RadioBox - the radio amateur's toolkit for RF

Posted: Fri Nov 20, 2015 6:11 pm
by Bulova
Hello Uli,

now I finally found the time to manage it and -- had fantastic success! RadioBox works great. I tested i. e. 1 MHz carrier and 1 kHz AM with 80 % grade. You certainly could imagine, what this is for. Yes, it is for EMC test. It would be very good to complete a functionality, where you can go frequency steps of 1 % and with a set time delay. This is for testing and observing the influence to a probe (EUT). It is not possible to go up to 80 MHz with RP, but at least to 50 MHz.
I will test the RadioBox for some more functions.


Re: RadioBox - the radio amateur's toolkit for RF

Posted: Thu Nov 26, 2015 11:20 pm
Thank you for your replies, folks!

Due to a flu I were some days off.

A time precision mode I have in mind. That was the first thing, when I made my GPS controlled 10 MHz-Ref.-Osc. @see there:

So simply spoken a VCTCXO would be taken to run on 20 MHz and to be clocked into the FPGA. In reverse direction a PWM signal would pull the VCTCXO to the exact frequency and phase. I
have done that already with the 10 MHz-Ref.Osc. It would be a pleasure for me to have that frequency/phase correction to be included to that RedPitaya board.

At the moment I have some works to do to have the "slow" XADC's running for the audio performance (in and out). By these modifications on the core for the PS (processing system) I found
out, that the core ran just on 500 MHz :lol: . Today I have successfully modified the clocking to 666 MHz full speed of the double core w/o any heat problems so far. All runs very smoothly now.

Next I would start with the SSB (USB/LSB) modulator, but I do understand that a sweep controller with start/stop and sweep-time adjusters would be fine. Ok, it is simple to implement and
the FPGA could do the job on its own after the right registers are programmed. That would make the CPU to loose another job to be done by the fast FPGA. ;)

So, thumbs up and until next time when the new RadioBox core runs on the latest ecosystem-0.94.

Vy 73
Uli, DF4IAH 8-)

Re: RadioBox - the radio amateur's toolkit for RF

Posted: Thu May 19, 2016 9:49 am
Today I like to announce the RadioBox RB_v0.94.08 release.

Binaries are available, here: ... (link is updated)

With this current release, this following features are implemented and running:
  • Receiver and Transmitter (at the same time running), with these voice modulation variants:
  • --> SSB (Single-Side-Band) as USB (Upper-Side-Band) and LSB (Lower-Side-Band)
  • AM (Amplitude Modulation)
  • FM (Frequency Modulation)
  • PM (Phase Modulation)
For the receiver part there are two AM demodulation variants. One decodes the AM as envelope (CORDIC magnitude),
the other does an AM synchron detection with the help of the SSB receiver branch where the carrier frequency
gets zero-beated.

All modulation and demodulation is done within the FPGA which allows the CPU to remain in idle state. That is a clear
difference to other SDR-solutions connecting the Red Pitaya as an ADC / DAC streaming device.

A nice frequency entering field allows fast entering and modification of the frequencies whith the help of:
  1. a dialer pad with erase and enter buttons.
  2. single digit up/down buttons.
  3. mouse-wheel controlled when pointer is hovered over the digits or up/down buttons.
  4. a frequency increment/decrement slider that instructs the FPGA to adjust the frequency 200.000x per second
    resulting to a glitch-free band scanning.
Input and Output of the RadioBox can be delivered by:
  • 2x RF In high-speed ADC-channels running @ 125 MSPS.
  • 2x RF Out high-speed DAC-channels running @ 125 MSPS.
  • 4x Audio In low-speed XADC-channels running @ 768 KSPS, where channel-0/8 is a stereo pair, and channel-1/9 the other one.
  • 4x Audio Out low-speed PWM-channels, not tested yet.
  • 2x Audio and/or SDR-data via Linux kernel AC97 sound driver in both directions handeled as common stereo-channels.
The new Linux sound driver allows to connect the RadioBox to every other SDR-software and/or to digital modulation variant
and data encoders or decoders like fldigi running on the Linux system of the Red Pitaya hardware.

The FPGA is enhanced for the RadioBox features, all other sub-modules are still working and could be used by the shared object for later use. A running scope or spectrum analysator could be implemented, when needed.

All ADC-channels are automatically offset corrected, there is no need for the user to interact with any offset voltage
problems that are based on bad offset values. This gives clear reception even on low signals.

Without any RF signal conditioning I am able to listen to 40 meter HAM radio as well as to the radio broadcast on the 41 m
and 31 m bands with a very clear and brilliant modulation on the night hours.

First sensitivity measurements gave me these figures:
  1. 75 µV SSB
  2. 350 µV AM-Synchro
  3. 500 µV AM-Envelope
  4. 700 µV PM
  5. 2500 µV FM

Have a screenshot of the current version:


Just received a test transmission on 9,760 kHz at 11:05 UTC, 2016-05-19:

FLAC compressed audio file: ... 05UTC.flac

Would be glad to see the RadioBox free application within the Bazaar. I do welcome the Red Pitaya team integrating
this sub-module into the Bazaar.
--> Thank you Črt and Pavel, all works fine now. The RadioBox app is now online at the Bazaar. :D


Vy 73
Uli, DF4IAH :)

Re: RadioBox - the radio amateur's toolkit for RF

Posted: Thu May 19, 2016 10:28 pm
by fisafisa

Re: RadioBox - the radio amateur's toolkit for RF

Posted: Fri May 20, 2016 2:20 pm
Now with automatic FPGA bit-file check and (re-)installation of a fresh RadioBox enabled fpga.bit file when needed to.

More details are here: ...

Find the latest app at the Bazaar:


Thank you for your comment, fisafisa. :D