Sunday, 27 June 2010
Comtech BSU479LX1DS Modules
Above is a photo of the inside of one of the Comtech modules I bought.
I plan using this module as a 1.3 GHz down converter so that I can
receive 1.3 GHz DVB-T on a domestic digital TV. Rather than using a PIC
controller to program the synthesiser I am considering using a USB chip
in its parallel port mode. I have a couple of DLP2232M-G development
modules. These can either be programmed as 2 serial ports or as two 8 bit
parallel ports. The spare lines I can use to control RF relays etc. I have used
these devices in the Windows environment but never under Linux.
Talking about DVB-T. I have now managed to get a stable transmission.
To do this I had to increase the size of the Kernel buffers that the UHD module
uses to communicate with the USRP2. I can now send up to 19 Mbits.
The TV reports a BER of zero. You can have too much of a good thing
though, if I increase the kernel buffers too much the whole program locks up
because all the internal queues empty and my program tries to fill them
with NULL transport packets.