SDR (Software Defined Radio) Transceiver

[martywittrock]

Pavel,

Just a note to let you know that I downloaded and loaded a new SD card with your latest image and it works wonderfully with the new PTT function and with the audio as you mentioned the other day. Outstanding work making this happen - you're making Red Pitaya compete with rigs costing hundreds of dollars more than what it costs to own a Red Pitaya.

Now if my PC boards will arrive for my T/R switch and receive and transmit amplification...Can't wait to get that going to have the Red Pitaya operating on the HF bands like the rest can...Stay tuned...

73 de Marty, KN0CK

[jgroves]

Hi Marty,

Does your board have provision for band pass and low pass filters, either on board or external? Or are you hoping to connect something like an ALEX setup?

It's beneficial to have band pass filters for the RX chain and before the TX power amp and then low pass filter after the power amp.


On another note...will your boards be available to buy once you've finished testing?

Kind Regards,

Julian. G1AUN

[dd8jm]

Hello Pavel,

I have a question, how do you implement the predistortion at Red Pitaya see.
If the FPGA suitable to implement this function?

If YES, you have to implement before this feature in the Red Pitaya.


Best wishes

Jörg de DD8JM

http://cq-nrw.de
http://forum.cq-nrw.de/

[martywittrock]

Julian,

When I designed the Preamp/PA board my design goals were:

1.) Provide 22dB gain for receive
2.) Provide a PA output of 10 - 15W with 12VDC power input
3.) Provide a T/R switch such that the independent receive and transmit I/Os were resolved to a single antenna connection
4.) Provide a connector on the Preamp/PA board to handle PTT keying such that common microphones could be wired into the system rather than the PC microphone
5.) Provide a 'mezzanine' structure to allow for easy connection/disconnection
6.) Provide an integrated fan for the FPGA that's not mounted on the Red Pitaya
7.) Keep all the filtering separate and on a completely different subassembly to allow for TAPR filters that work well with PowerSDR to be used, or wait for my designed filter assembly
8.) Allow provisions later on for upconversion to allow the Red Pitaya to operate in the 2m Band (to be implemented)

All those things are in my current designed board and I have 3 prototype boards that were sent to fab last Friday (2/19) and I expect that they will be depaneled and sent to me within the next 3 - 4 days. I have all the parts for my first prototype in hand - so when the boards arrive I'll be able to populate all three, but they'll be 'first cut' boards and subject a subsequent design spin for the boards that will qualify for 'first production' run. I'm anticipating that in the next two weeks I'll have my first prototype built and will be testing it. If all goes well, then I will do a final spin and resubmit that design for fab of 20 boards about the middle of March - - some of those will be built with the intention to be sold at the Dayton Hamvention in late May, but I would think I will have a few to sell and I'll keep you posted on that. Just watch the posts here on my progress.

But, yes, the receive preselect and the transmit PA filtering will not be part of this assembly due to size. The current board design I have matches the size of the Red Pitaya and will mount with standoffs to keep it a fairly unified assembly.

Keep watching for the progress posts here - 73,

de Marty, KN0CK

[pavel]

I have a question, how do you implement the predistortion at Red Pitaya.
If the FPGA suitable to implement this function?
If YES, you have to implement before this feature in the Red Pitaya.

Hello Jörg,

I agree that it would be nice to have predistortion implemented. At the moment, it's not implemented.

However, I could not find any detailed description of how predistortion (Pure Signal) is implemented by the HPSDR project. The only sources of information that I currently have are

• the Hermes source code: http://svn.tapr.org/repos_sdr_hpsdr/tru ... 1/Hermes.v
• this recent forum thread: http://lists.openhpsdr.org/pipermail/hp ... 71746.html

I can't find where the Pure Signal algorithm is implemented in the PowerSDR mRX code:
http://svn.tapr.org/repos_sdr_hpsdr/tru ... DR_mRX_PS/

There are also technical problems. The Hermes FPGA code uses two additional receivers for the Pure Signal algorithm. I'm afraid that I can't add two receivers to the SDR HPSDR application for Red Pitaya. However, I could try to add one more receiver and reuse the existing receivers in some way.

Without more detailed information about the Pure Signal algorithm, I can add some code that would behave more or less similarly to the Hermes code but I don't know if it's enough for the Pure Signal algorithm to work with Red Pitaya.

Best regards,

Pavel

[pavel]

I've just found a bug in the FPGA configuration of the SDR HPSDR application. The GPIO debouncer module was connected to a wrong clock signal. It's fixed in the following commit:
https://github.com/pavel-demin/red-pita ... 4b34546482

The new version (0.94-874) is now available via the Red Pitaya application market place. I've also updated the customized SD card image.

[dd8jm]

Hello Pavel,
thanks for the, as always quick reply.
I have the mail published in our forum maybe there is someone who has more information about the Theam.
Best wishes
Jörg

[Onnosr]

Dear Pavel,

Openhpsdr has a CWX window.
On that windows are a knob "Key" and a knob "Keyboard" to activate the keyboard.
But using it does not activate transmitting. The leds in the left upper corner are working.
Is there a solution or do I see something wrong.

And many thanks for your work !

Onno PA0ONO

[pavel]

Openhpsdr has a CWX window.
On that windows are a knob "Key" and a knob "Keyboard" to activate the keyboard.
But using it does not activate transmitting. The leds in the left upper corner are working.
Is there a solution or do I see something wrong.

On the HPSDR hardware, a significant part of the CW/CWX functionality is implemented in FPGA and consists of the following modules:

http://svn.tapr.org/repos_sdr_hpsdr/tru ... 1/iambic.v
http://svn.tapr.org/repos_sdr_hpsdr/tru ... /profile.v

There is an interesting discussion of this problem on the Hermes-lite mailing list:

https://groups.google.com/forum/#!topic ... uhZmuDNZko
https://groups.google.com/forum/#!topic ... Pte1OypQBQ

At the moment, it's not clear to me how to implement the CW/CWX functionality in the Red Pitaya SDR transceiver compatible with HPSDR.

A possible workaround could be using fldigi:
http://www.w1hkj.com/

Some instructions on how to interface fldigi with PowerSDR mRX can be found at the following link:
http://www.coilgun.info/hamradio/hermes-sdr.htm

[pavel]

I've added two receivers required by Pure Signal.

The new version (0.94-881) is now available via the Red Pitaya application market place. I've also updated the customized SD card image.

To use Pure Signal with Red Pitaya, some PowerSDR settings should be adjusted. The following screenshots show the settings that work for me. To access the "Calibration Information" panel press Ctrl+Alt+i. The attenuated feedback signal from the amplifier should be connected to IN2.