Using gnuradio as a amateur radio

GNU Radio
1

Hi all,
I’m using gnuradio to receive and transmit to 2 meters amateur radio,
and when
I went to buy the cable, I didn’t know what impedance should I use w/
the
usrp. 50 ohm or 75 ohm?

Can I connect an amplifier to the basic-tx without any problem?

thanks
rafael diniz

2

On Mon, Jun 16, 2008 at 05:48:05PM -0300, rafael2k wrote:

Hi all,
I’m using gnuradio to receive and transmit to 2 meters amateur radio, and when
I went to buy the cable, I didn’t know what impedance should I use w/ the
usrp. 50 ohm or 75 ohm?

Can I connect an amplifier to the basic-tx without any problem?

thanks
rafael diniz

Please explain to me how you are planning on transmitting on 2 meters
using the basic tx daughterboard and how you are planning on
controlling out of band emissions.

Thanks,
Eric

3

Hi Eric

thanks
rafael diniz

Please explain to me how you are planning on transmitting on 2 meters
using the basic tx daughterboard and how you are planning on
controlling out of band emissions.

By 2 meters (the wave length) radio I mean the range of 144-148 Mhz
(here
in brazil, is the band for amateur radio class C) - I can receive and
transmit using the examples that come w/ gnuradio (fm_tx4.py and
usrp_nbfm_rcv.py).

I already bought an small antena (1/4 of wave length - its working), but
I’d like to put an antenna in the top of my home (to receive, w/
basic-rx), so I’d like to know what impedance (for the cable) should I
use.

Another issue is that in the future I would like to put an amplifier in
the output of the basic-tx to reach farther places. Is it simple as I
think it is?

USRP is really a great piece of hardware!!

I did not thought about the out of band emissions yet… may be I could
add some filters too…

Thanks,
Rafael D.

4

On Wed, Jun 18, 2008 at 12:24:46AM -0700, [email protected] wrote:

It’s a 50 Ohm single-ended input. You could interface with a common
ameatur 2m amp as long as the input is 50 Ohm. Most amps include a
strict band filter.

Jonathan

FYI, when using the Basic Tx to transmit in the 2m band (144MHz),
we’re running in the second nyquist zone. Unless you use a serious
amount of filtering, the vast majority of the power emitted is “out of
band”.

Eric