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Author Topic: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator  (Read 10214 times)

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Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #75 on: July 24, 2017, 07:36:38 PM »
Does the JDS6600 carry a CE mark?

I'm asking, because without it German customs may
have me return the unit or scrap it at my cost which is not funny.

Yes, I know the CE story. It basically means China Export :-DD
yes, we have CE mark for JDS6600, you can go to our page to check
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #76 on: July 24, 2017, 08:07:49 PM »
Having 11 Bit resolution is already quite good from an simple R2R chain at the FPGA. For me it looks surprisingly good.
Medium grade DDS chips like the AD9850 only use an 10 Bit ADC, though they use a longer table (e.g. 4096 points). With just 2048 points for a period, there is limited use of more than 10 Bit resolution though.

The staircase like waveform with quite some ringing suggests that there is no good reconstruction filter. So one can expect quite some high frequency images. The fast output amplifier also has some disadvantages here.

Some jitter in the square wave is normal for directly generating the square from the FPGA.
thank you for your answer, our Waveform vertical resolution is 12 bit, 4096 points, and waveform is about 2048 points . so at x-2048 points, y-4096 points, at this
coordinate system, it show our waveform. For  R2R , it is not easy to design, because it is hard to design, so many DDS don't use this way, if it is design better , it will be more stable than chiop way.
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #77 on: July 24, 2017, 08:19:31 PM »
The jitter should not depend on the H/L ratio. It should be just a question of the 5 ns time raster. So it depends on the frequency too. This might even be the worst aspect of it. At frequencies that don't have a period that is an integer multiple of 5 ns will show the jitter. So more like low jitter only at a few special good frequencies.
This generator does not have jitter at non-multiple frequencies, unlike other budget DDS.
 

Offline Diabolo

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #78 on: July 25, 2017, 03:41:08 AM »
Hello,

Here are some curves with FY2300H.
Square 10Mhz
-
Sinus 25 Mhz
-
Triangle 20 Mhz
-

Only everything is not perfect, the suite is here:
- https://www.eevblog.com/forum/testgear/new-generateur-dds-avec-altera-cyclone4/

Sorry for the hs.
Regards,
Diabolo
 
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Offline Enoch

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #79 on: July 25, 2017, 12:48:23 PM »
I received my JDS6600 yesterday, phase tracking no problem. :scared:
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #80 on: July 25, 2017, 03:54:29 PM »
I received my JDS6600 yesterday, phase tracking no problem. :scared:
Turn on infinite persistence And tuning of frequencies.
When the frequency is tuned, the synchronized second channel loses the phase randomly.
« Last Edit: July 25, 2017, 04:20:30 PM by pantelei4 »
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #81 on: July 25, 2017, 04:06:04 PM »
The jitter should not depend on the H/L ratio. It should be just a question of the 5 ns time raster. So it depends on the frequency too. This might even be the worst aspect of it. At frequencies that don't have a period that is an integer multiple of 5 ns will show the jitter. So more like low jitter only at a few special good frequencies.
This generator does not have jitter at non-multiple frequencies, unlike other budget DDS.
at square wave, our wave is not jitter . this is my advantage. so you have JDS6600, you can check
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #82 on: July 25, 2017, 04:10:24 PM »
The jitter should not depend on the H/L ratio. It should be just a question of the 5 ns time raster. So it depends on the frequency too. This might even be the worst aspect of it. At frequencies that don't have a period that is an integer multiple of 5 ns will show the jitter. So more like low jitter only at a few special good frequencies.

Depending on how frequency calibration is done the good frequencies can be slightly different, depending on the exact quartz frequency. In principle they could use a different frequency scale - allowing only good ones (e.g. divider) and maybe warn about poor ones.
yes, that is a standar too to judage a DDS
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #83 on: July 25, 2017, 04:19:21 PM »
A special DAC chip is generally better than using just a resistor chain at the FPGA output. Most DACs do not offer that much of isolation between the digital side and analog output. So noise is in both cases a question of a good layout. This is still a low cost generator - so the cheap resistor ladder DAC is a kind of compromise.

The failure is to label it 14 Bit resolution if they actually only get 11 Bits.

The Resistor chain looks like 8 Bit R2R and 14 or 15 resistors thermometer style. So at best they could get something like 12 Bit resolution. Still I am surprised how good it seemed to work. If not careful, even at 8 Bits R2R one can get significant errors. One sees that with other low cost generators that call for 8 or 12 Bit resolution and only deliver 6-7.  With an actual 11 Bit resolution it is already a big step forward.

Using true 14 or maybe just 12 Bit DACs is a cost factor - though they might save on the amplitude control this way.
About  a resistor chain at the FPGA output, I have explain, and your explain is good and right too , for any plan, it was designed better , it will all be good.
about the bit, I don't why where you find, because we write 12 bit Waveform vertical resolution , not 14bit.
about the 14 bit , we have updated, but we only sell at china for now. because we need to test in china, after test, and no one find the problem, so we sell to the world. it is our rule for publishing the products. all our products have this progress.
thank you for your support again
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #84 on: July 25, 2017, 04:23:42 PM »
we have updated, but we only sell at china for now. because we need to test in china, after test, and no one find the problem, so we sell to the world. it is our rule for publishing the products. all our products have this progress.
thank you for your support again
Why then I received an imperfect product? |O
 

Offline qq354813374

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #85 on: July 25, 2017, 04:40:29 PM »
Form the picture it looks like the DAC is not a pure R2R chain, but more like using thermometer style for the upper bits. So maybe someone confuses the 14 I/O pins used for control with a 14 bit resolution. At least the DAC seems to work reasonably well as 11 Bit this way.

The DAC type does not have direct influence on the noise with small signals. The waveform should be generated at constant amplitude and only the following multiplier and attenuators reduce the amplitude if needed.

You can look at the delicate degree of 14bit waveform

I'm sorry to be rude, but I am a bit concerned about your posts in this thread. I think you are trying to imply from the context and content of your posts that you are a mere consumer who has tried the Rui-Deng model and a FeelTech model function generator. Your profile says you're from England.

However:
  • you list "feeltech" in your profile
  • your username is typical of the email addresses offered primarily to Chinese users by Tencent
  • a google search for that username reveals other posts in Chinese in various technical forums
  • your English, while adequate, leads me to believe you speak English as a second language
  • FeelTech is headquartered in China, and I'm not able to find any offices in the UK

I should note that all of this is just from information you offered (your username, listing feeltech in your profile) or otherwise publicly available information. And I don't know of any reason or rule that one's profile must be correct on this forum, so I doubt you've done anything wrong. I suppose I could believe that you are an Chinese expat living in the UK.

In any case, if you do work for Feeltech (and perhaps if you designed the product you are discussing) I  think you should be up front and honest about that fact. After all, who else would be better qualified to analyze the properties of a modern cheap function generator than a person who just designed a modern cheap function generator?

Thanks.

First of all, I am a Chinese, I did not deliberately hide my nationality, I and everyone like FeelTech users, which is me in the "forum" learning reasons, because here you can get more technical articles, out of By chance, I saw RD Tech in the forum to promote FeelTech product designers are their students, so I will call to FeelTecH confirmation. Got FeelTecH designer Sun Yi Jie negative answer. At the request of Sun Yi Jie, I made a comparison of the FY6600 and JDSS6600, responded to the "Forum"


« Last Edit: July 25, 2017, 04:43:21 PM by qq354813374 »
 
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Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #86 on: July 26, 2017, 04:28:09 PM »
products are being updated. we are working on it. if we sloved alll problem, i will tell you
 

Offline SaabFAN

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #87 on: August 03, 2017, 06:44:14 AM »
Can these problems be fixed in software and can user update the firmware themselves?

Or is this more a hardware-issue?
How can customers tell the difference between the updated and non-updated devices?

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #88 on: August 03, 2017, 01:53:09 PM »
Can these problems be fixed in software and can user update the firmware themselves?

Or is this more a hardware-issue?
How can customers tell the difference between the updated and non-updated devices?
there are two small problem,
1, background noise, it was caused by DC power supply. it is small and it doesn't affect normal using , I can make sure
2, at low frequency for square wave form, when you amplify 1000 times, you will find that there is little no sync. this don't affect normal using .
excep those , otheres are not my problem.
because those are small problem and don't affect normal using , so we gradually update those things. now we have already update 2 problem, if you order now
thank you for your concern
have a nice day
 

Offline SaabFAN

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #89 on: August 04, 2017, 05:20:17 AM »
Okay, good to know.
But is there a possibility to install new Firmware via USB, or can the Firmware only be updated by programming the microcontroller via the JTAG-Header?

If the latter is the case, I'd suggest that this feature is implemented as soon as possible, as it will add significant value to the instrument. If any problem is discovered that can be corrected with a firmware-update, users can just update to the new firmware instead of buying a new unit or living with that problem. It also allows you to add features later, maybe as paid options, further adding value.

Offline SaabFAN

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #90 on: August 04, 2017, 05:31:37 AM »
It also appears that the JDS6600 does not have the capability to modulate the signal, is that correct?

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #91 on: August 04, 2017, 05:50:47 PM »
Okay, good to know.
But is there a possibility to install new Firmware via USB, or can the Firmware only be updated by programming the microcontroller via the JTAG-Header?

If the latter is the case, I'd suggest that this feature is implemented as soon as possible, as it will add significant value to the instrument. If any problem is discovered that can be corrected with a firmware-update, users can just update to the new firmware instead of buying a new unit or living with that problem. It also allows you to add features later, maybe as paid options, further adding value.
Thank you for your reply , friend
in fact , those are no problem. it don't affect our using totally. we only say it is not perfect, because there is no perfect thing in the world. those thing are just like there is small dot on shell of a device , those don't affect normal using totally, useless you use a magnifying glass to see , you can see this dot.
but we are trying to make it perfect .. thank you
about the modulating the signal , we don't have this function, because this is a just DDS signal generator ..
thank you again . hope you understansd what I said
 :)
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #92 on: August 28, 2017, 04:16:44 PM »
Brands shopping week will begin from 28st Aug to 1 st Sep ( US time). There is the Biggest discount in this year on aliexpress, there are many coupons on aliexpress. And our shop discount is from 17% off - 30% off. And there are many coupons:
8 usd for over 75 usd value at home page  (https://rdtech.aliexpress.com/store/923042 )
And 2 USD , 3 USD . 5 USD coupons.
1, DP and DPS power supply : 24%-30% off https://rdtech.aliexpress.com/store/group/Power-Supply-module/923042_252253169.html?spm=2114.12010608.0.0.2995e5c0hedOO2
2, USB Tester meter : 24%-30% off https://rdtech.aliexpress.com/store/group/USB-Tester-meter/923042_250764074.html?spm=2114.12010612.0.0.5bdadf47DMFSF9
3, 7 in 1 OLED multifunction meter 24%-27% off https://rdtech.aliexpress.com/store/group/7-in-1-OLED-METER/923042_502024032.html?spm=2114.12010612.0.0.5bdadf47VDGoeX
4, JDS6600 : 20% off (23% off at phone app) https://rdtech.aliexpress.com/store/group/DDS-SIGNAL-GENERATOR/923042_252907419.html?spm=2114.12010612.0.0.5bdadf47O3g0YO
Hope this can help you. Happy shopping
Have a nice day
Best Regards
RD official store
 

Offline smarteebit

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #93 on: September 02, 2017, 05:58:16 PM »
yes, we have CE mark for JDS6600, you can go to our page to check

Where is your web page?  Could you please provide your official website?
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #94 on: September 02, 2017, 06:46:16 PM »
yes, we have CE mark for JDS6600, you can go to our page to check

Where is your web page?  Could you please provide your official website?
https://rdtech.aliexpress.com/store/923042
you can check
 

Offline pascal_sweden

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #95 on: September 02, 2017, 07:20:55 PM »
Do you maintain a list with an overview of all known hardware and software problems?

In this list you can each time add new problems and also indicate which problems that are solved.

You can give each problem a title, and classify it as a hardware problem, a software problem or a combination of both.

You can indicate in which hardware revision, and/or software revision the problem has been solved.

When customers order a product on your webstore, you can indicate which hardware revision and which software revision they will get. This avoids discussions later on, as the customer will know upfront what he will get.

Good luck in fixing all your hardware and software problems! :)
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #96 on: September 04, 2017, 01:05:39 PM »
Do you maintain a list with an overview of all known hardware and software problems?

In this list you can each time add new problems and also indicate which problems that are solved.

You can give each problem a title, and classify it as a hardware problem, a software problem or a combination of both.

You can indicate in which hardware revision, and/or software revision the problem has been solved.

When customers order a product on your webstore, you can indicate which hardware revision and which software revision they will get. This avoids discussions later on, as the customer will know upfront what he will get.

Good luck in fixing all your hardware and software problems! :)
thank you so much for your advice , it is good idea.
but we did not make a record . because those problem is small problem, don't affect normally using , so we did not record those .
thank you again
now we have update all those small problem.
 


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