Re: [Discuss-gnuradio] Using USRP w/o Daughterboard's

[Robitaille, Michael]

> > frequencies to get the data rate up some.  Based on my current 

> > specification, none of the DB would be of much use so I am trying to 

> > use the USRP w/o daughterboard's.

 

John's response

> Don't.  Use the Basic daughterboards.  The main board itself has no useful
connectors for hooking up your

> signals.  The Basic daughterboards translate the high-pin-count
daughterboard connector to a couple of SMA

> connectors and to a bunch of debug headers.

 

> Matt has posted how to get very low frequencies -- all the way to DC

> through the Basic daughterboards.  You have to do something like replace
the transformer on the Basic 

> daughterboard, which couples the SMA connectors onto the motherboard
connector.  I can't find his message

> right now, but I've attached a note where he talks about the issue.

 

I modified a connector to input the signal at the same daughterboard pins
(pins 60 and 62) that the J18 connector feeds basically bypassing the
transformer.  The only problem is that the software is looking for the card,
most likely getting a signal from the eeprom chip that identifies the board.
There is no real processing or substantial signal conditioning on the board
(only takes an unbalance input and converts it to balance).  If I could just
bypass the software that looks for the eeprom respond, I could just use my
modified 64 pin connector to connect to the USRP.

 

Could you please point me to a reference of how I can modify the Basic RX
DB?  I looked and could not find it on this board so far.

 

Thanks,

 

Mike