Re: [Discuss-gnuradio] Fwd: Problem in uhd_fft

[Karan Talasila]

Hi Josh,

            we tried using the same grc flowgraph and tried transmitting at frequencies 33Mhz and 35 Mhz. Though we could see a constant source output on the fft, the frequency at which that was occuring was at -31Mhz and -29Mhz. The output log is shown below for frequency of 33 Mhz. I have attached a screenshot of my grc too.

enerating: "/home/anrc/Downloads/top_block.py"

Generating: "/home/anrc/Downloads/top_block.py"

Executing: "/home/anrc/Downloads/top_block.py"

linux; GNU C++ version 4.6.3; Boost_104800; UHD_003.004.005-0-unknown

Using Volk machine: sse4_1_64

-- Opening a USRP1 device...

-- Using FPGA clock rate of 64.000000MHz...

UHD Warning:

    The hardware does not support the requested RX frequency:

    Target frequency: 33.000000 MHz

    Actual frequency: -31.000000 MHz

-- Opening a USRP1 device...

-- Using FPGA clock rate of 64.000000MHz...

U

>>> Done

On Thu, Jul 4, 2013 at 6:36 AM, Josh Blum <address@hidden> wrote:

On 06/29/2013 09:14 AM, Karan Talasila wrote:
> ---------- Forwarded message ----------
> From: Karan Talasila <address@hidden>
> Date: Sat, Jun 29, 2013 at 6:44 PM
> Subject: Re: [Discuss-gnuradio] Problem in uhd_fft
> To: "address@hidden" <address@hidden>
>
>
> Hi Josh,
>             I am using USRP 1.   I am using a sma-bulkhead cable from Tx_A
> of basic tx daughter board and similarly a sma-bulkhead cable from Rx_A
> terminal of the Basic Rx daughter board. and then i am connecting a sma-sma
> cable from usrp transmitter to a coupler on powerline cable. Similarly I am
> connecting a sma-sma cable from usrp receiver to another coupler on the
> powerline cable.
>
> so in all I am using 2 usrp 1, 2 sma-sma cables, 2 sma-bulkhead cable and
> two couplers. Please let me know if i am not clear with the description.
> Thank you.
>

Seems to work OK for me. I used a single USRP1, BasicRX, BasicTX. RXA is
connected to TXA and RXB is connected to TXB. Attached is a GRC flow
graph. Hope that helps.

-josh

>
> On Sat, Jun 29, 2013 at 11:24 AM, Josh Blum <address@hidden> wrote:
>
>>
>>
>> On 06/27/2013 09:44 AM, Karan Talasila wrote:
>>> Hi,
>>>       I am using a basic tx and basic rx daughterboard for transmission
>> and
>>> reception. The spec says basic tx and basic rx run from 0 to 250 MHz. But
>>> when i run transmitter and check the uhd_fft at receiver, after 32 Mhz,
>>> there is no signal. If i set the transmitter frequency in my flowgraph as
>>> 33 MHz, I don't get a signal at 33 Mhz, But when i enter frequency as
>>> -31Mhz in the uhd_fft i get a received signal on my fft. why does this
>>> happen? If it's in the range of daughter board it should be receiving it
>> at
>>> that particular frequency right.
>>>
>>>
>>
>> Can you tell me more about the cabling setup? Which ports of the Basic
>> TX and RX are you using, and how are they connected via SMA cable?
>>
>> -josh
>>
>>>
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>
>
>
>
>
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--
Regards
Karan Talasila

Screenshot from 2013-07-04 11:09:24.png
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