Re: [Discuss-gnuradio] A rfx2400 is down, which chip on the borad is broken?

[Lin HUANG]

What are you doing to the boards?

We are using the rfx2400s to make a 2*2 MIMO-OFDM platform. We also run some other programs like usrp-fft, spectrum sensing etc.

What are you connecting them to?

2 common 2.4G antennas, not the PCB antennas from Ettus.

What level signals are you connecting to the inputs?

RF signal from air. According to the received data in PC, I don't think they are too high. And we have used them for several weeks with the current connection.

What are you using for the power supply?  The one that came from Ettus
Research, or something else?

They are exactly the ones from Ettus Research.

 

The story is like this: We use the platform everyday. Then in someday morning or afternoon, we started the USRP and found they had no responses?! Nobody touched the boards during the period. And when we leave the lab, we always shut off the power of the boards. The enclosures are usually open because we often plug in and out the daughterboard. At that time we are always very careful.

 

So we are very confused. What's the reason?
 

HUANG Lin
 

2007/5/24, Eric Blossom <address@hidden>:

On Thu, May 24, 2007 at 07:35:15PM +0800, Lin HUANG wrote:
> Hi everybody,
>
> I'm the colleague of Hanwen. Today I checked the broken board. I need
> your
> help especial Ettus' help.
>
> We can assure that the mother board is OK, because when we plug other
> rfx2400, it works well. For this broken rfx2400:
>
> 1. The switch control signal, U204 7404
> A1 B1 A2 B2 : 0 1 0 1
> It seems no problem. And 3.3V voltage is normal.
>
> 2. The TX side: For the power supply circuit, U111 ADP3336 has input 6V
> and
> output 5V and U110 has 5V input and 3.3V output. For the AD8349,
> VCC=5V, and
> ADF4360 has VCC=3.3V. They all seem normal. But when we run the transmit
> program, the graph always stops immediatly and there is no any error
> report
> on screen. I'm very confused with this.
>
> 3. The RX side: the power circuit U6 has 6V input and 5V output, but U5
> cannot output 3.3V. So U3 ADF4360 has no power supply. If U5 is the
> reason
> for board broken, I can try to replace this chip.
>
> But I'm not sure the broken chip is U5. I remember Ettus said that the
> TX
> and RX path is completely indenpendent. Why our TX path doesn't work
> either?
> Untill now we have already broke THREE rfx2400s, all with the same
> problem.
> I worry about other boards will be broken too.
>
> Can anybody give some advice? Thank you very much!
>
> HUANG Lin

What are you doing to the boards?

What are you connecting them to?

What level signals are you connecting to the inputs?

What are you using for the power supply?  The one that came from Ettus
Research, or something else?

Eric