Virtual Trackgen

Information and discussions on Spectrum Analysis
PeterW
Posts: 8
Joined: Sat Apr 06, 2019 7:08 am

Re: Virtual Trackgen

Postby PeterW » Sun Apr 14, 2019 11:58 am

AussieSusan wrote:
cmr77 wrote:I'm tempted to get one of the ADF4351 board and have a play with some filtering as it's a cheap device.

Agreed that it is a cheap device but how do you intend to go about the filtering.
The 'simplistic' approach is a LPF that would cut out the higher frequency harmonics of the square wave. But the issue I see is that the LPF would need to be tuneable.
At the low end of the frequency range - lets say 50MHz for an example, - the harmonics are at 150Mhz, 250MHz,350MHz etc. All of these are perfectly valid frequencies that the device can create as the fundamental frequency. Therefore any LPF that would work at the low end of the frequency range would remove all higher fundamentals as well.
Trying to make a tuneable LPF or BPF that covers such a wide range of frequencies would be an engineering challenge I suspect.
The data sheet for the device really only talks about how to use the device for 2.2GHz and up frequency output and you need to use the internal 'divide by x' register for the lower frequencies which is why the signal is 'squared up'.
I think that this chip would be very useful for the range it is intended to be used, but that other DDS chips would be better at the lower frequencies.
Susan


I have ordered a test board from this guy, https://www.sv1afn.com/adf4351m.html

currently on back order but his plot seems fine anyway on small bandwidth tho.
But I will test it myself on my old HP8566B spectrum analyzer, my goal is to have some tracking possibility up to 500 MHz
over that it is more difficult to make filters anyway, and I think if I cover the most used HAM bands could be a practical use .

I have used in another project the AD9910 with is little more expensive but have a fine sinewave up to 400 MHz it is based up on a 14 Bit DAC

I get back with test result when i have them, meanwhile Steve have to enable Spectrum analyzer software do accept DDS tracking for frequency over 90 MHz

//Peter
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M1ASR
Posts: 6
Joined: Tue Feb 06, 2018 5:46 pm
Location: Skipsea, UK

Re: Virtual Trackgen

Postby M1ASR » Sun Apr 14, 2019 6:43 pm

I’m interested in putting together a virtual tracking generator system and I’m new to Arduino (Used raspberry pi’s up to now) but I’m happy to learn. Where can I find out more about where to download the virtual trackgen software and info on interfacing to pc etc?

Thank you

Graham
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Regards
Graham

SteveAndrew
Posts: 206
Joined: Thu Nov 16, 2017 11:06 pm
Location: Gold Coast, QLD, Australia

Re: Virtual Trackgen

Postby SteveAndrew » Mon Apr 15, 2019 12:32 am

M1ASR wrote:I’m interested in putting together a virtual tracking generator system and I’m new to Arduino (Used raspberry pi’s up to now) but I’m happy to learn. Where can I find out more about where to download the virtual trackgen software and info on interfacing to pc etc?

Thank you

Graham

Hi Graham

Check the first post in this thread for the virtual Trackgen source code. It only very basic skeleton code in C# to demonstrate how to connect to the analyser. You will only need this if you intend to develop your own tracking generator. If you intend to use an AD9850 or an AD9851 then the Arduino firmware zip files can be found in the analyser's installation directory - see manual.

Steve

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M1ASR
Posts: 6
Joined: Tue Feb 06, 2018 5:46 pm
Location: Skipsea, UK

Re: Virtual Trackgen

Postby M1ASR » Fri Apr 26, 2019 7:25 pm

Hi Steve,

Thanks for the info. AD9851 arrived today, so hopefully up and running next week. I found Need to research how to upload hex files to Arduino now?

Regards
Graham
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Regards
Graham

Mike2459
Posts: 320
Joined: Mon Jul 24, 2017 8:24 pm

Re: Virtual Trackgen

Postby Mike2459 » Fri Apr 26, 2019 9:36 pm

Uploading hex files with XLoader.exe is much much simpler than using the command line tool.

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M1ASR
Posts: 6
Joined: Tue Feb 06, 2018 5:46 pm
Location: Skipsea, UK

Re: Virtual Trackgen

Postby M1ASR » Sat Apr 27, 2019 11:22 am

Thanks for all the help on this thread (I will read the manual next time as well). First experience with arduino (raspberry pi man), so now up to speed with that as well.

All up and running. Checked spot frequency @ 10Mhz and bang on.

I'm wondering if there are any plans to use the ADF4351, which would nicely compliment the 9851 and allow tracking 35Mhz - 2Ghz?

I am a Radio Amateur, experimenting with DATV. I have built a transmitter operating 437Mhz, 1.2Ghz and 2.4Ghz so the addition of an extended range would be more than helpful.

Regards
Graham
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Graham

SteveAndrew
Posts: 206
Joined: Thu Nov 16, 2017 11:06 pm
Location: Gold Coast, QLD, Australia

Re: Virtual Trackgen

Postby SteveAndrew » Sun Apr 28, 2019 4:16 am

M1ASR wrote:All up and running. Checked spot frequency @ 10Mhz and bang on.

Hi Graham

Is that with the Arduino running the Trackgen firmware ? - If so, did you experience any problems getting the analyser to connect to the Arduino module ? which Arduino module are you using ?

M1ASR wrote:I'm wondering if there are any plans to use the ADF4351, which would nicely compliment the 9851 and allow tracking 35Mhz - 2Ghz?

PeterW has one on order and hopefully will report his findings. If it turns out to be useful, then I'd certainly consider adding support for it.

Steve

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M1ASR
Posts: 6
Joined: Tue Feb 06, 2018 5:46 pm
Location: Skipsea, UK

Re: Virtual Trackgen

Postby M1ASR » Sun Apr 28, 2019 10:22 pm

Steve,

I’m using the Arduino UNO (Chinese). Connection sometimes requires a couple of goes, but when connected sweeps as designed. I did notice that the 9851 amplitude reduces quite a bit towards the top end of its range. This isn’t an issue for narrow band sweeps.

Regards
Graham

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Regards
Graham

SteveAndrew
Posts: 206
Joined: Thu Nov 16, 2017 11:06 pm
Location: Gold Coast, QLD, Australia

Re: Virtual Trackgen

Postby SteveAndrew » Mon Apr 29, 2019 12:34 am

M1ASR wrote:I’m using the Arduino UNO (Chinese). Connection sometimes requires a couple of goes, but when connected sweeps as designed. I did notice that the 9851 amplitude reduces quite a bit towards the top end of its range. This isn’t an issue for narrow band sweeps.

Hi Graham

Thanks for the information. The connection problem is being looked into. Amplitude reduction of the DDS output as frequency increases is normal. This thread discusses the same problem and includes a link to a very informative web page that explains why this is so. As it mentions, some DDS systems apply the correction internally, or you could calculate the correction factor needed for any frequency, and apply it to the data point you are measuring.

viewtopic.php?f=12&t=4336&start=10#p14966

Steve

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PeterW
Posts: 8
Joined: Sat Apr 06, 2019 7:08 am

Re: Virtual Trackgen

Postby PeterW » Tue Apr 30, 2019 6:05 pm

SteveAndrew wrote:
M1ASR wrote:All up and running. Checked spot frequency @ 10Mhz and bang on.

Hi Graham

Is that with the Arduino running the Trackgen firmware ? - If so, did you experience any problems getting the analyser to connect to the Arduino module ? which Arduino module are you using ?

M1ASR wrote:I'm wondering if there are any plans to use the ADF4351, which would nicely compliment the 9851 and allow tracking 35Mhz - 2Ghz?

PeterW has one on order and hopefully will report his findings. If it turns out to be useful, then I'd certainly consider adding support for it.

Steve


Hi all , I have now get my first ADF4351 board, I have tested it first on a arduino and I found 2 problem it was 2 CAPs that was bad so output power was limited and Refinput CAP was also bad so i have changed them so now it is up and running ok.

As I am more to Microchip PIC I will translate the source to run on PIC instead but right now I have limited time for this project but I will work on it as soon as possible.

I update info here as the progress go.

//PW

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