New HAM-radio multimode beacon

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pe1mxp
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New HAM-radio multimode beacon

Postby pe1mxp » Sun Sep 13, 2015 9:24 pm

Hi all.

Since a year I have a HAM-radio beacon running in the 4m amateurband.
I did this with the populair AD8950 and an Atmega (ofcourse a 28Mhz-70Mhz
transverter with PA too). The Idea I got from the OZ7IGY beacon (google it).
But one mode was not enough to experiment, so programmed more modes.
Now I am running CW, PI4, ISCAT-B and JT9H mode. And this is the end
of capabilities because an AD8950 in serial programming mode has his
limits. And I want to go up for 2000bd frequency hopping. Also it has very
bad inband harmonics. So decide to buy another DDS, an AD9910 with higher
sampler rate (1Ghz). Also it has parallel programming (the AD8950 does also,
but still slow and bad signal ouput). So looking for the right processor (and cheap)
I buyed a blue pill C8T6. So I have a nice project for the winter to learn and
experiment.

73 de Roelf, pe1mxp@hotmail.com

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ahull
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Re: New HAM-radio multimode beacon

Postby ahull » Sun Sep 13, 2015 10:17 pm

I'm a little unclear, do you mean AD9850 and/or AD9959 - I'm not familiar with the part numbers you quoted. I was however thinking of having a play with the AD9850 at some stage to add a 0 - 40 MHz signal generator to the $10 scope.
- Andy Hull -

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mrburnette
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Re: New HAM-radio multimode beacon

Postby mrburnette » Sun Sep 13, 2015 11:56 pm

@pe1mxp

Welcome to the forum.

Ray
Silly projects: https://www.hackster.io/rayburne

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RogerClark
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Re: New HAM-radio multimode beacon

Postby RogerClark » Mon Sep 14, 2015 5:54 am

@pe1mxp

I have an AD9850 and produced FM audio using it, but changing the frequency very quickly. From what I recall it works OK even on 100Mhz but very little output.

I'm not familiar with the other Tx modes you wrote about. FM and CW should work also PSK (but thats similar to FM) as the AD9850 has a phase control.

I can't recall if the AD9850 can do AM, i.e whether there is an output level control.

PS. I have a UK ham license in perpetuity (G4KYF) but as I no longer live in the UK I am not active

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ahull
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Re: New HAM-radio multimode beacon

Postby ahull » Mon Sep 14, 2015 9:35 pm

pe1mxp wrote:Hi all.

Since a year I have a HAM-radio beacon running in the 4m amateurband.
I did this with the populair AD8950 and an Atmega (ofcourse a 28Mhz-70Mhz
transverter with PA too). The Idea I got from the OZ7IGY beacon (google it).
But one mode was not enough to experiment, so programmed more modes.
Now I am running CW, PI4, ISCAT-B and JT9H mode. And this is the end
of capabilities because an AD8950 in serial programming mode has his
limits. And I want to go up for 2000bd frequency hopping. Also it has very
bad inband harmonics. So decide to buy another DDS, an AD9910 with higher
sampler rate (1Ghz). Also it has parallel programming (the AD8950 does also,
but still slow and bad signal ouput). So looking for the right processor (and cheap)
I buyed a blue pill C8T6. So I have a nice project for the winter to learn and
experiment.

73 de Roelf, pe1mxp@hotmail.com



You might also be interested in this SI5351A board from Adafruit. It claims to be able to produce frequencies from 8KHz to 160MHz (and you can also pick it up on ebay for a few bucks more).

It might also make an interesting clock source for STM32/GD32 experiments.
- Andy Hull -

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martinayotte
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Re: New HAM-radio multimode beacon

Postby martinayotte » Mon Sep 14, 2015 11:35 pm

There was even an article on Hackaday yesterday about this board and/or chip : http://hackaday.com/2015/09/13/arduino- ... ital-mode/

pe1mxp
Posts: 10
Joined: Sun Sep 13, 2015 7:11 pm

Re: New HAM-radio multimode beacon

Postby pe1mxp » Wed Sep 16, 2015 6:19 pm

martinayotte wrote:There was even an article on Hackaday yesterday about this board and/or chip : http://hackaday.com/2015/09/13/arduino- ... ital-mode/


Yes, I knew that. Disadvantage of the Si5351A/SI570 is it has only a square-wave. But directly on frequency it can work.
And also a D-class amplifier with BS170 works good. But had to do with a SBL-1 rf-mixer and a Mitsubishi 30W module.
So I chose for an AD8950. Beside that, I had already some breakout boards.

pe1mxp
Posts: 10
Joined: Sun Sep 13, 2015 7:11 pm

Re: New HAM-radio multimode beacon

Postby pe1mxp » Wed Sep 16, 2015 6:44 pm

RogerClark wrote:@pe1mxp

I have an AD9850 and produced FM audio using it, but changing the frequency very quickly. From what I recall it works OK even on 100Mhz but very little output.

I'm not familiar with the other Tx modes you wrote about. FM and CW should work also PSK (but thats similar to FM) as the AD9850 has a phase control.

I can't recall if the AD9850 can do AM, i.e whether there is an output level control.

PS. I have a UK ham license in perpetuity (G4KYF) but as I no longer live in the UK I am not active


Were you that guy on YouTube, bitbanging music on the parallelport of the AD8950?
Well, when you ever have checked the output on a spectrum analyzer an AD8950
is even bad on HF with inband harmonics and high noise level. Therefor a DDS
with higher sample rate and a higher bit-resolution.
All modes I make are in FM (FSK), so a single frequency. Not experimented
with PSK because it was not necessary.
But the AD8950 has some limitations. And to be prepared for the future,
experimenting and a clean RF signal I chose for a expensive fast DDS (US5,- vs US$80,-)

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RogerClark
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Re: New HAM-radio multimode beacon

Postby RogerClark » Wed Sep 16, 2015 8:30 pm

Were you that guy on YouTube, bitbanging music on the parallelport of the AD8950?


No. Whoever did that on YouTube it was not me.

I recall using the ADC on a Uno and fed the values to the AD9850, to constantly change its fequency and then listened on a normal FM radio on around 100Mhz. The signal was easily detectable and the audio seemed clean

pe1mxp
Posts: 10
Joined: Sun Sep 13, 2015 7:11 pm

Re: New HAM-radio multimode beacon

Postby pe1mxp » Thu Sep 17, 2015 10:36 pm

RogerClark wrote:
Were you that guy on YouTube, bitbanging music on the parallelport of the AD8950?


No. Whoever did that on YouTube it was not me.

I recall using the ADC on a Uno and fed the values to the AD9850, to constantly change its fequency and then listened on a normal FM radio on around 100Mhz. The signal was easily detectable and the audio seemed clean


I know that trick. Playing with dirty signals. Now I am busy to figure out which pins I can use to connect the DDS.
Use TIM1, so those I/O pins I cannot use. Also a GPS is connected with 1PPS. In my previous project with the AD8950
I used an Atmega. That was simple. On the new DDS I go a STM32C8T6 for serial usage, like register setting and
for single frequency mode. And using a 2nd STM32C8T6 for using the parallel mode. In all facts, setup the DDS
for every mode is only via serial. And I noticed also why they use a FPGA. When doing a parallel bitbang, my speed
aprox, 3 times higher compared with the serial programming. But the maximum speed for changing the I/O is 27ns.
According the DDS datasheet I can speed up the data transfer rate 4x but therefor I need a faster CPU. Well, everything
is fast enough for the now know digital modes for HAM-radio. I will prepare my PCB design so that I can exchange
the parallel cpu for a FPGA.


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