USRP for Ku band?

GNU Radio
1

Is it possible to utilise USRP2 with a daughter board to receive a
signal on
the Ku band? I checked Ettus website but all the available
daughterboards
have carrier frequencies less than the required.

What do you think?

Cheers,

Zohair

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2

Yes,

For example, use an TV LNB as a downconverter, LO 10.7-12.75 GHz, then
use
an L-band receiver (DBSRX, etc)

Patrik

----- Original Message -----
From: “Zohair” [email protected]
To: [email protected]
Sent: Monday, February 20, 2012 12:33
Subject: [Discuss-gnuradio] USRP for Ku band?

3

On 20/02/12 05:33 AM, Zohair wrote:

Is it possible to utilise USRP2 with a daughter board to receive a signal on
the Ku band? I checked Ettus website but all the available daughterboards
have carrier frequencies less than the required.

What do you think?

Cheers,

Zohair

The usual way people do that is to use a Ku-band LNBF – the same type
that people use for satellite TV.
These downconvert into L-band, so a DBSRX or WBX card can be used to
receive the downconverted
signal. Get one that is “digital ready”–they have better local
oscillators that are more stable.

Typical units downconvert 11.7GHz to 12.7GHz down to 950Mhz to 1800MHz.

–
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

4

That’s great! I will do that. Thank you very much.

Zohair wrote:

–
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5

Dear all,

I am trying to implement the DVB-S2 satellite standard which has two
sample
rates:

30.9 MBaud and 29.7 MBaud.

My question is : can USRP N210 sample at these sample rates?

I don’t seem to be able to decimate the 100 MSps to these rates. is
there
away to do this?

Would you direct me to a usefull documentation regarding this issue,
please?
Thanks

Zohair wrote:

What do you think?

Cheers,

Zohair

–
View this message in context:
http://old.nabble.com/USRP-for-Ku-band--tp33353983p33407375.html
Sent from the GnuRadio mailing list archive at Nabble.com.

6

On Tue, Feb 28, 2012 at 7:23 AM, Zohair [email protected] wrote:

I don’t seem to be able to decimate the 100 MSps to these rates. is there
away to do this?

You can only sample at integer decimations of the 100Msps native sample
rate of the N210. So you can get 50Msps (only possible with 8 bit
sampling,
recently added to UHD), 33.3333Msps, 25Msps, 20Msps, etc.

DVB-S2 uses QPSK or 8PSK, so your symbol rate will be divided down from
the
bit rate accordingly, and the required sample rate is a function of
symbol
rate (plus rolloff), not bit rate. As a result, you can sample at lower
sample rates than the native bit rate to receive your DVB-S2 signal. The
rolloff of DVB-S2 30.9Mbit is 0.20, so the maximum channel occupancy of
a
30.9Mbit QPSK (2 bits per symbol) stream would be
1.20*(30.9e6/2)=18.54MHz.
Sampling at 20Msps with the N210 would suffice in this instance to
completely capture the signal. For 8PSK 29.7Mbit (rolloff=0.25, 3 bits
per
symbol), you need 1.25*(29.7/3)=12.375Msps. The closest sample rate
would
then be 12.5Msps.

If your decoding scheme requires an integral number of samples per
symbol,
you can resample the incoming stream using Gnuradio’s polyphase
resampler
block to achieve whatever sample rate you require.

–n