DATV Express unmodulated carrier

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g8vpg
Posts: 387
Joined: Fri Oct 11, 2013 9:35 am

DATV Express unmodulated carrier

Post by g8vpg » Wed May 18, 2016 3:15 pm

I have been using my DATV Express for 146.5MHz operation, mostly 333ks/s. Suddenly, without knowingly making any changes, it is only outputting an unmodulated carrier. I cannot see anything wrong with the Vmix or DATV Express software settings. Whilst doing this, it is also rapidly filling up the TX buffer. Any advice would be greatly appreciated.
73 Shaun.

G4GUO
Posts: 729
Joined: Tue Feb 16, 2010 12:51 pm

Re: DATV Express unmodulated carrier

Post by G4GUO » Wed May 18, 2016 4:44 pm

Hi Shaun,
I suspect the Express board software has crashed you will need to re-cycle the power on the board
and restart the application. It is probably due to a USB issue. The buffer filling up means the
board has ceased to read the USB2 data.

- Charles

g8vpg
Posts: 387
Joined: Fri Oct 11, 2013 9:35 am

Re: DATV Express unmodulated carrier

Post by g8vpg » Wed May 18, 2016 5:45 pm

Charles,
Thank you for responding so quickly. Yes, that did the trick. Maybe I am overtaxing a modest laptop by running both Vmix, DATV Express and Minitioune on the same device. I have a solution in preparation; I have ordered one of the Lynx 1010b Windows tablets so that I can split transmit and receive between two computers.
73 Shaun.

G4GUO
Posts: 729
Joined: Tue Feb 16, 2010 12:51 pm

Re: DATV Express unmodulated carrier

Post by G4GUO » Wed May 18, 2016 8:01 pm

I suspect the issue is in the FPGA code design. I think that occasionally the board can get into a state
where it can't recover and the only solution is to re-power it. It happens most often when it starts
up or when you do a restart. Both times a lot of I2C messages are sent to the chips on the board
and I think that is when it occurs. Usually when it is up and running the problem does not occur and that
is because little I2C traffic occurs over the internal bus.

- Charles

g8vpg
Posts: 387
Joined: Fri Oct 11, 2013 9:35 am

Re: DATV Express unmodulated carrier

Post by g8vpg » Thu May 19, 2016 7:35 am

Thanks for your quick help and support Charles. Shaun.

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