Author Topic: Siglent SDG830 sync bug in sweep?  (Read 1226 times)

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Offline paul

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Re: Siglent SDG830 sync bug in sweep?
« Reply #25 on: August 22, 2020, 03:13:05 pm »
Looks like Siglent updated the user manuals for the older non X models a while ago and added a section on the sync output.
Both the SDG1000 and SDG800 have the same section in the new manuals on the sync output showing how the output state changes for the mode etc.
eg. “For a Sweep, when the sweep starts, the Sync Signal becomes TTL Level High. The Sync frequency equals the specific Sweep time.”

This whole section is missing from my original manual, which is probably a good thing as unfortunately it does not work that way on the SDG1000, the sync output changes in sweep mode to output a pulse at the beginning of the sweep (and it still works if the stop frequency is 20MHz).
The `Trig out` BNC socket on the rear panel outputs the square wave of the sweep time, which is where you would expect to find it, but only if enabled in the sweep menu.

Which brings me to the Sync option in the Utility menu. I was only getting a 200mV pulse out of the Sync BNC socket until I found the Sync menu, and the fact that you have to press “Done” for any change in settings to take affect, now I have a 5V sync pulse :) and no this is not covered in the manual. :(

So it looks like the manuals are not quite 100% correct, or complete just yet (or keeping up with firmware changes ?)
 

Offline regenfreak

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Re: Siglent SDG830 sync bug in sweep?
« Reply #26 on: August 22, 2020, 05:17:45 pm »
Quote
Which brings me to the Sync option in the Utility menu. I was only getting a 200mV pulse out of the Sync BNC socket until I found the Sync menu, and the fact that you have to press “Done” for any change in settings to take affect, now I have a 5V sync pulse :) and no this is not covered in the manual. :(

So it looks like the manuals are not quite 100% correct, or complete just yet (or keeping up with firmware changes ?)

I have heard quite a few users got caught out by this poor user interface. How many people do sweep without sync?

Quote
which is probably a good thing as unfortunately it does not work that way on the SDG1000, the sync output changes in sweep mode to output a pulse at the beginning of the sweep (and it still works if the stop frequency is 20MHz).

Beside the obvious bug, the SDG830 only gives out pulse sync which really  sucks for determining the center frequency on the scope. I am not trying to bash Siglent products. They make great stuff.  If you do not do sweep with sync, it is perfectly fine. For me it is a deal breaker, I returned mime and got a full refund rather than mucking around and using another signal generator to produce sync square waves.. I am going to purchase the Rigol  1022Z which suits more for RF AM and FM receiver alignment.
My hats off to Siglent engineer acknowledging the bug and listening to users' feedback though.
« Last Edit: August 22, 2020, 05:24:19 pm by regenfreak »
 

Offline paul

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Re: Siglent SDG830 sync bug in sweep?
« Reply #27 on: August 22, 2020, 10:03:02 pm »
Quote
I returned mime and got a full refund rather than mucking around and using another signal generator to produce sync square waves.

I can understand this, no telling how long it will take for a bug fix, although Siglent were quite quick fixing the log sweep bug a few years ago :)

I have to correct my previous comment on the Sync output working at 20MHz on sweep, there is a pulse at the start of the sweep only its at the low level of 30mV (I forgot I had the 10x on the scope) . Once you go above 2MHz with the Sync output on there is a warning message on the screen and the Sync output is disabled (not completely as it still `leaks` out at 30mV)

From the manual (For the SDG1000 and SDG800)

   “For non-modulated waveform, the Sync Signal reference is the carrier.”

This works up to 2MHz, as per spec. (it actually is still outputting a 30mV pulse correctly up to 3.9MHz after that it gets a bit random)

   “For internal modulating AM, FM and PM, the Sync signal reference is the modulated signal (not the carrier signal).”

Again this works only when the carrier is below 2MHz, although the output is still there in its disabled state reduced to 30mV. This a obviously a bug :(

   “For ASK and FSK, the Sync Signal Reference is the keying Frequency.”

Same as above :(

   “For a Sweep, when the sweep starts, the Sync Signal becomes TTL Level High. The Sync frequency equals the specific Sweep time.”

This one we know about :) 

   “For the Burst, when the burst starts, the Sync Signal is Level High.”

Again limited to 2MHz, in Ncyle the Sync pulse is at the 50% point between the bursts, in Gated its at the start of the burst.

   “For the External Gated Burst, the Sync Signal follows the External Gated Signal.”

Nope, it stays with the internal signal :(

I can only assume theses are rarely used functions, especially by me :) as I have not seen these problems reported before, but if you need them or bought the generator after reading the spec / manual specifically needing this functionality I can see how this would be an issue :(
 

Offline regenfreak

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Re: Siglent SDG830 sync bug in sweep?
« Reply #28 on: August 22, 2020, 10:45:43 pm »

Quote
Again this works only when the carrier is below 2MHz, although the output is still there in its disabled state reduced to 30mV. This a obviously a bug :(

Damn. :palm:

Quote
I can only assume theses are rarely used functions, especially by me :) as I have not seen these problems reported before, but if you need them or bought the generator after reading the spec / manual specifically needing this functionality I can see how this would be an issue :(

Perhaps I am a rare minority hobbyist that still builds and repairs valve and transistor FM radios using sync sweep.

 I was pulling my hairs out when i could not do FM sweep with the SDG830.  :-BROKE I kept doubting myself  :-/O, doubting my Silgent SDS1202x-E trigger function, and thinking I was using it wrong. :horse: Even I bought a new Rigol DS1201 Z-E scope because I thought my Siglent SDS1202X-E had bugs with the normal trigger function.   

Now I have both 200MHz Siglent and Rigol scopes, it is not a bad thing as sometimes, measurement looks funny in one scope, i can switch to another scope to see the difference,
 

Offline egonotto

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Re: Siglent SDG830 sync bug in sweep?
« Reply #29 on: August 23, 2020, 02:21:08 am »
Hello    regenfreak,

try to use the arb waveform. Define a waveform with 10 sinus periods with EasyWave. And sweep with arb with 1.07 MHz center. Maybe the sync out works than. The generator gives 10 time the frequency thus 10.7 MHz.

Best regards
egonotto
 

Offline regenfreak

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Re: Siglent SDG830 sync bug in sweep?
« Reply #30 on: August 23, 2020, 08:55:10 am »
Hi As i wrote above, the Uk dealer has given me full refund for the SDG830.  I will order a Rigol DG1022Z and will not need to mess around finding fix of the bug. On reflection, i learnt a great deal about how sweep sync works. So the experience was not all negative.
« Last Edit: August 23, 2020, 08:57:27 am by regenfreak »
 

Offline TurboTom

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Re: Siglent SDG830 sync bug in sweep?
« Reply #31 on: August 23, 2020, 07:52:15 pm »
Why don't you consider a DG811 and hack it to perform as a DG992. This has to be by far the best option for hobby users from a price vs. performance point of view. The enclosure may look a little (urgh) funny...but otherwise, it's a decent design. Have a look at the corresponding thread if you like.
 

Offline regenfreak

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Re: Siglent SDG830 sync bug in sweep?
« Reply #32 on: August 23, 2020, 08:15:12 pm »
I have pulled the trigger and ordered the Rigol DG1022Z.  This model is a bit old now but I am 100% sure it will do hassle-free sweep sync. 

I am not an adventurous type who would want to hack something and void the warranty. I am not sure if the  DG811 can do exactly what I want. I may save $100 but I risk encountering the same problem as in the Siglent SDG830.

 I have learnt the lesson of false economy :palm:... wasting lots of time and money to acquire cheap gears and they turn out to be no good, and you know the score. :rant:
« Last Edit: August 23, 2020, 08:26:01 pm by regenfreak »
 


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