FY6800 - DDS signal generator questions - Page 1
Forum section: electronics / testgear

author: Andreas
author_rank: Super Contributor
timestamp: June 22, 2019, 07:29:07 pm
content: Hello,I am trying to use the USB connection of the FY6800 since I plan to write a software to automate some measurements.There are 2 things that I have found which are annoying:(At least with the "delivered" documentation which is also not complete).I want to do 80% AM modulation (e.g. 1kHz) on a variable frequency (sweep) and amplitude.1) every time that I change the frequency with the WMF command e.g. with a terminal program then the AM modulation gets switched off. I will have to re-switch on with the undocumented "WPM4" command.Which a) cost time (~400ms) and b) gives together with issue 2) glitches on the output power.2) When doing AM I would expect that when I switch on the modulation that the average amplitude remains the same and changes between 20% and 180% with 80% modulation against the 100% unmodulated signal.Not so the FY6800: the modulated signal changes between 20% and previous 100%.This way the 80% AM modulation turns out to be only m = (1.03-0.217) / (1.03 + 0.217) = 65% instead of 80%.Are there any (undocumented) commands which solve my issues?with best regardsAndreas

author: windsmurf
author_rank: Frequent Contributor
timestamp: June 22, 2019, 11:19:35 pm
content: Quote from: Andreas on June 22, 2019, 07:29:07 pmMaybe just make the 100% level your desired 180%?1.03v x 1.8 = 1.854vFor the desired 80% modulation (20% level), set it to : 1 - (1.03v x 0.2) / (1.03v x 1.8 ) = 88.3%

author: Andreas
author_rank: Super Contributor
timestamp: June 25, 2019, 04:13:04 am
content: Hello,most probably this will be the way to go.on the other side: when I change the frequency manually by using the rotary switch: the AM modulation is not switched off.So there should be also a way to change the frequency from the USB interface without switching off the AM.with best regardsAndreas

author: ed512
author_rank: Newbie
timestamp: August 21, 2019, 09:03:25 pm
content: My FY6900 seems to have a USB interface but the supplied DDS Signal PC Software does not connect or seem to be able to connect. The user's manual does not say anything clear about the interface. I have noticed in this forum that some users have been able to connect their PC to the FY6900. What am I doing wrong?

author: Andreas
author_rank: Super Contributor
timestamp: August 21, 2019, 09:27:49 pm
content: Hello,assuming that the FY6900 is not different to the FY6800 in this regard:- You need a CH340/341 driver for the USB interface.- when attaching the USB-connection you should get a new virtual COM-Port in the Device Manager.- You should be able to communicate with a terminal-Program "WMF100000000" should set the frequency to 100 Hz.- Some programs do not work with COM-Ports above COM-Port 9 -> eventually re arrange the COM-Port numbers- I have tried the FY6800 Software together with my FY6800-> it works on a Windows XP machine which I have used together with "portmon" to log the commands.The main functions should not be different between the models. (so perhaps the FY6800 Software is worth a try).Can you check if my 2 problems regarding remote control are still there with the FY6900? (either with a terminal program or with the delivered software)with best regardsAndreas

author: ed512
author_rank: Newbie
timestamp: August 21, 2019, 09:40:19 pm
content: MY FY6900 user manual states: "Under setting frequency status, press ADJ Knob to change frequency units among MHz, KHz, Hz, mHz, μHz."I want to change the units from kHz to Hz. How do I access the 'setting frequency status' screen? Also, my adjust knob does not have a 'press' function; it only rotates.

author: ed512
author_rank: Newbie
timestamp: August 21, 2019, 09:43:30 pm
content: What is a CH340/341 driver? I am using a Win7 machine.

author: bdunham7
author_rank: Super Contributor
timestamp: August 22, 2019, 03:37:39 am
content: Quote from: ed512 on August 21, 2019, 09:40:19 pmPress the "FREQ" button, then use the 'OK' button to change the units. I guess they forgot to rewrite that part...

author: ed512
author_rank: Newbie
timestamp: August 22, 2019, 03:20:09 pm
content: Yes, I think there is a lot they forgot to write. I am not very good at guessing how to use something; I usually need specific instructions. Anyway, your frequency units instructions worked. Thanks.Do you know anything about the USB interface? From another post response I learned that the interface is not like every other USB interface on the planet. Apparently I need to do some hacking to make their user interface chat with the generator.