Juma TRX2A and DSP

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Juma TRX2A and DSP

Postby NQ3RP » 13 Dec 2017 20:39

I read in the manual > "DsPIC30F6014A is also clocked with this reference oscillator. The
current software version operates with a 30MHz clock. The 30MHz frequency is connected to the micro
controller via 0R jumper R54. For future use there is the possibility to install a flip flop IC6 and get 7,5MHz
external clock rate for the dsPIC30F6014A micro controller. This “low frequency” clock is needed if the
dsPIC30F6014A internal PLL is used for clock frequency generation. With internal PLL , the 120MHz
clock rate can be produced. This is needed if software performs heavy DSP operations."

Is anyone doing this or is there a possibility to implement this in the near future, maybe REV. D board?

John
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Re: Juma TRX2A and DSP

Postby 5B4AIY » 14 Dec 2017 07:03

Hi, John,

Whilst I do not know what may be the future intentions of the designers, I would have to say that, in my opinion, a DSP version of the TRX2A is highly unlikely, for the following reasons:

1. In order to digitally process the signal, there would have to be a connection from the audio stages to the A-D convertor. This would require major surgery to the existing printed circuit boards.

2. Equally, after processing the audio you would want to recover it, and this would also mean adding a D-A convertor, again, involving some major surgery.

3. The on-board A-D is only a 12-bit device, and whilst some signal processing could be performed with this limited word length, most other transceivers employing a DSP chip use much larger word sizes.

Therefore, I cannot honestly see any prospect of a DSP version using the existing hardware. It would involve such a major re-design that it would be far better to start from scratch with a completely new hardware design, and take advantage of the improvements in IC performance that have been made since this transceiver was originally conceived.

Of course, I could be wrong! I would be delighted if someone out there had actually managed to implement a DSP version of this really nice little rig, but I'm not holding my breath on this.

73, Adrian, 5B4AIY
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Re: Juma TRX2A and DSP

Postby NQ3RP » 15 Dec 2017 14:16

Adrian -

I agree with the changes that would have to be made, also the A/D would have to be changed, etc. But I think it would be easy to do with another board containing an A/D, D/A and a STM processor doing the Fourier transform. Would need to changed the clock speed to 7.5Mhz in that case, the 160Mhz would be fine. Not sure how I would integrate into the software for DSP filter, band width, etc. Might try this as an experiment next year.

John
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Re: Juma TRX2A and DSP

Postby 5B4AIY » 16 Dec 2017 07:44

Hi, John,

Taking another look, if you were to use a plug-in daughter board using the voice memory option connector, you have access to the audio in/out, microphone in/out as well as the SPI bus, and thus there is a possibility of incorporating an advanced DSP module without any surgery, or, at most only a minor amount. Take a look at the voice memory option board schematics.

As the firmware, including mine, accesses and controls the voice memory module, this could be re-designed and re-written as a DSP control module. The problem comes when you try to integrate a user interface - there are simply no more push buttons available, and even my firmware makes full use of both primary and secondary button functions for all the existing buttons.

To attempt to incorporate a third level function would certainly pose a challenge, it would depend on just how much user control of a DSP module would be required apart from configuration and setup. These actions could easily be incorporated into the existing calibration and setup and user configuration menus.

So, without even modifying the existing clocking arrangements, if a plug-in DSP daughter board were designed to use the existing voice memory option connector, and if this board incorporated its own microprocessor and was controlled via the existing SPI bus, then very little hardware modifications would be necessary, and the DSP controls could be incorporated into the existing firmware.

To see what existing firmware modifications would be required, take a look at my firmware, and in particular the isd1700.c voice memory control module, as well as the various button logic modules, and the calibration and setup, and user configuration routines to give you an idea of how to extend these for DSP setup.

Food for thought?

73, Adrian, 5B4AIY
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Re: Juma TRX2A and DSP

Postby NQ3RP » 16 Dec 2017 12:54

Adrian -

I will look at your firmware and thanks for the tips about the voice memory connection description. I've run into the problem with limited button / function problem in many hardware interface routines before. I see that each button is used in several ways but there is no combination of buttons. The Button A is checked for short push or long push or maybe even double push but not A +B (a knew function for DSP filter setting for example) or B + C for band width. I'm not ready to dig into the software as I only got the kit today. But will look at this in a few months. I'll let you know what I come up with. Thanks for your input and will be asking for more advice since you are the expert with the TRX2A.

John\NQ3RP
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Re: Juma TRX2A and DSP

Postby OH2NLT » 26 Dec 2017 19:57

Days back when TRX2 DDS board was designed I was also experimenting with DSP radio concepts. My old experimental project can be found here
http://www.kolumbus.fi/juha.niinikoski/ ... ap_dsp.htm

I had plans to make codec option board and implement at least DSP filters maybe speech processor etc digital audio functions. For this reason dspic30F6016 prosessor was selected. 30F6014 is overkill for rest of the radio control functions. Option connectors J5, J7 and J8 enables access to the audio path and contains all CODEC bus signals CSDI ... COFS.
If you like to experiment with DSP functions my old Cheap_DSP project may give you good starting point.

We did not agree about DSP options and no DSP add on board was never done for the TRX2. Small Microchip based DSP transceiver however saw light in different format on the other side of the world.
http://www.sdr-cube.com/
dsPIC is not the most powerful DSP architecture but enough for to implement full featured digital transceiver. dsPIC benefits are price and "manageable hardware". Simple enough for understandinh how things works and physical chips are TQFP format not many hundred pin ball grid arrays.

Fine moments with your DSP experiments. 73 Juha oh2nlt
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