IF Frequency of WBX board

Hello G.s,

What is the IF frequency of the WBX board? I could not find this in the
WBX documentations. Any pointers? Thank you.

Kind regards,
Yahia Tachwali

On 03/28/2011 02:18 PM, Tachwali, Yahia wrote:

Hello G.s,

What is the IF frequency of the WBX board? I could not find this in the WBX
documentations. Any pointers? Thank you.

The IF frequency is generally the error in tuning between the target
center frequency and the actual center frequency. You can also manually
control the tuning, so the IF frequency could be anywhere between +/- 40
MHz (for example).

Theses links may be relevant to you:

See
http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html

Also see
http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__result__t.html

-Josh

Hello Josh,

Thank you very much for the reply. It seems to me that these functions
are generic and not WBX specific. If I understood you correctly, WBX
board does not have a fixed IF frequency. I had some experience with
other SDR platforms where their RF boards have fixed IF frequencies at
30 MHz (Super-heterodyne receiver). This is not the case for WBX board?

Kind regards,
Yahia Tachwali


From: [email protected]invalid
[[email protected]invalid] on behalf of Josh
Blum [[email protected]]
Sent: Monday, March 28, 2011 5:23 PM
To: [email protected]
Subject: Re: [Discuss-gnuradio] IF Frequency of WBX board

On 03/28/2011 02:18 PM, Tachwali, Yahia wrote:

Hello G.s,

What is the IF frequency of the WBX board? I could not find this in the WBX
documentations. Any pointers? Thank you.

The IF frequency is generally the error in tuning between the target
center frequency and the actual center frequency. You can also manually
control the tuning, so the IF frequency could be anywhere between +/- 40
MHz (for example).

Theses links may be relevant to you:

See
http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html

Also see
http://www.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__result__t.html

-Josh


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http://lists.gnu.org/mailman/listinfo/discuss-gnuradio

On 03/29/2011 11:29 AM, Tachwali, Yahia wrote:

Hello Josh,

Thank you very much for the reply. It seems to me that these functions are
generic and not WBX specific. If I understood you correctly, WBX board does not
have a fixed IF frequency. I had some experience with other SDR platforms where
their RF boards have fixed IF frequencies at 30 MHz (Super-heterodyne receiver).
This is not the case for WBX board?

Kind regards,
Yahia Tachwali
All boards except for the original TV_RX use a Zero-IF architecture,
wherever possible. Sometimes, however, the coarseness of the PLL
synthesizer on the RF cards requires a little bit of “clean up”, so
that the final stage of down-conversion is done in the FPGA to convert
your
desired center frequency to DC. For example, if the PLL synthesizer
can only “tune” in 25KHz steps, and you’ve asked for a frequency
that isn’t a multiple of 25KHz, the cooperation between UHD, the FPGA
seeks to make sure that your baseband DC frequency is precisely
(within 1Hz, and subject to the accuracy of the master clock) where
you expect it to be.

The TV_RX used an IF at (if I recall correctly) 5.75MHz, which was
down-converted inside the FPGA to DC. I think the new TV_RX2 uses
a Zero-IF architecture, but I’m happy to be corrected on this.

The Zero-IF or direct-conversion approach has distinct benefits over a
superheterodyne approach, although it does require a
complex (I and Q) “format” in order to make it work correctly.


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

OK, It is clear now. Thank you very much to all.

Kind regards,
Yahia Tachwali


From: [email protected]invalid
[[email protected]invalid] on behalf of Marcus
D. Leech [[email protected]]
Sent: Tuesday, March 29, 2011 3:47 PM
To: [email protected]
Subject: Re: [Discuss-gnuradio] IF Frequency of WBX board

On 03/29/2011 11:29 AM, Tachwali, Yahia wrote:

Hello Josh,

Thank you very much for the reply. It seems to me that these functions are
generic and not WBX specific. If I understood you correctly, WBX board does not
have a fixed IF frequency. I had some experience with other SDR platforms where
their RF boards have fixed IF frequencies at 30 MHz (Super-heterodyne receiver).
This is not the case for WBX board?

Kind regards,
Yahia Tachwali
All boards except for the original TV_RX use a Zero-IF architecture,
wherever possible. Sometimes, however, the coarseness of the PLL
synthesizer on the RF cards requires a little bit of “clean up”, so
that the final stage of down-conversion is done in the FPGA to convert
your
desired center frequency to DC. For example, if the PLL synthesizer
can only “tune” in 25KHz steps, and you’ve asked for a frequency
that isn’t a multiple of 25KHz, the cooperation between UHD, the FPGA
seeks to make sure that your baseband DC frequency is precisely
(within 1Hz, and subject to the accuracy of the master clock) where
you expect it to be.

The TV_RX used an IF at (if I recall correctly) 5.75MHz, which was
down-converted inside the FPGA to DC. I think the new TV_RX2 uses
a Zero-IF architecture, but I’m happy to be corrected on this.

The Zero-IF or direct-conversion approach has distinct benefits over a
superheterodyne approach, although it does require a
complex (I and Q) “format” in order to make it work correctly.


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org


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