Re: [Discuss-gnuradio] VHF Transmitter

[Pavol Ďuriš]

BasicTX allow transmit only up to 44MHz, isn't it ?

Pavol Duris

Dimitris Symeonidis  wrote / napísal(a):

What about BasicTX, which does 1-250MHz?

Dimitris Symeonidis
"If you think you're too small to make a difference, try sleeping with
a mosquito!" - Amnesty International



On Thu, Nov 27, 2008 at 15:22, Ed Criscuolo <[EMAIL PROTECTED]> wrote:
  

The project I'm working on (an SDR for a spacecraft
communication groundstation) needs to transmit VHF at
around 145 MHz.  There seems to be a distinct "gap"
in the transmit capabilities of the USRP daughterboards
between 32 MHz and 400 MHz.

I'm looking for suggestions as to how to best accomplish
this.  My initial thought was to output at 10 MHz using
an LFTX board, and upconvert to 145 MHz with an external
mixer, LO, and filter. This seems straightforward, but
would be a custom implementation, and my project wants
to stay with commercial-off-the-shelf if possible.

Another suggestion was to skip the modulation (GMSK) and
output the baseband signal with an LFTX.  This could then
be fed into a commercial off-the-shelf VHF FM transmitter.

I was also wondering if it would be possible to modify
an RFX-400 daughterboard to go down that low (Matt?).

Anyway, I was hoping to hear what people thought of these
suggestions, and any others they might have.

@(^.^)@  Ed



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Re: [Discuss-gnuradio] Interest in beamforming and GNSS receivers

[Pavol Ďuriš]

Hi all,

I have an interest in radioastronomy. I plan to make simple beamforming 
phase array (primary with 4 and later with 8 antennas) with USRP (later 
with 2) and GNU Radio. I am inspired by LOFAR radiotelescope.
Now I collect all available information about using GNU Radio and USRP 
for it.


Martin, could you send more information about your solution, project 
(url etc.) ?


Thanks,
Pavol

PS: I haven't USRP yet. However, I am buying my first USRP, right now :)

Martin Dvh wrote:

Carles Fernandez wrote:
  


How well are they synchronized?


They run off the same 64 MHz clock, so are synchronised.
I have even used two connected USRPs running of the same clock (one is master 
and exports its clock to the slave USRP)
(You use an additional flatcable between the USRPS and an align software block 
in gnuradio which aligns the samples)
This gives you 8 ADCs. This means 8 real channels or 4 complex channels.

I used this setup for a phase array with 4 DBSRX daughterboards.
(DBSX daughterboards use complex sampling so they need two ADCs)
DBSRX boards also support the GPS frequencies and are a lot cheaper, so you 
might want to consider them.
But they are receive only.

You can even go higher and connect 4, 8 or 16 USRPS.
  
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