Forum: GNU Radio Radio interoperability

03d96e38f7592042a54ebf4760d069c0?d=identicon&s=25 Bijendra Singh (Guest)
on 2013-10-10 09:29
(Received via mailing list)
Attachment: ssb_rx.grc (40 KB)
Attachment: hf2vhf.grc (60 KB)
Attachment: fmtxtest.grc (60 KB)
Attachment: fmrxu.grc (40 KB)
Attachment: ssbtx1.grc (30 KB)
Hello every one,
I'm working on a college level project to show interoperability between
HF
and VHF radio using GNU radio.
My aims are listed below:
1)   To obtain FM transmitter and receiver waveform in GNU radio as
flowgraph, so that i can communicate between laptop and VHF radio (In my
case I'm using radio of the range 30-89.899 MHz)  :- This I have already
achieved

2)    To obtain AM transmitter and receiver waveform in GNu radio as
flowgraph, so that I can communicate between laptop and HF radio (In my
case I'm using a HF radio of the range 3-30 MHz)    :- I was able to
download a SSB receiver and it is functional but the noise level is
high.

3)   To integrate Fm transmitter with AM receiver, so that one way
communicaton is possible from HF radio to VHF radio. :- This I have
already
achieved, but with too much of noise and low pitch voice.

4)   To integrate AM transmitter with FM receiver so that one way
communication is possible from VHF radio to HF radio.  I'm still lackung
behind in this.

5)  To integrate both the 3rd and 4rth flowgraphs in a single flowgraph
to
make Hf and VHF radio interoperable from both sides.

6)  My GNU version is 3.6.4.1, I'm using two usrp's 1 for the HF with
lftx
and lfrx daughter boards and the other for VHF with basic trans and
basic
receive daughter cards.Also I'm using dipole antenna.

&0 Please guide me. I'm here attaching some .grc file I have downloaded,
and which are working in my GNU, but noisy( only ssb_rx is noisy and
sstx1
is not working)
Ad80d352eb445a3d7dccd5a779db0e43?d=identicon&s=25 Martin Braun (CEL) (Guest)
on 2013-10-10 10:24
(Received via mailing list)
Hi Bijendra,

it's not quite clear what your question is.

A couple of things you might want to consider:

- AM is per se noisy. A commercial HF receiver would also have much
  better filters than you can achieve with an LFRX-only setup, so expect
  much noise here
- FM is much better with noise.
- You're not supposed to rx AM signals with an FM receiver.
- VHF and HF usually designate (separate) frequency ranges. So when
  talking about 'interoperability' between those, most people will be
  confused. Well, I am.

MB

On Thu, Oct 10, 2013 at 12:58:06PM +0530, Bijendra Singh wrote:
>
>
> lfrx daughter boards and the other for VHF with basic trans and basic receive
> daughter cards.Also I'm using dipole antenna.
>
>
> &0 Please guide me. I'm here attaching some .grc file I have downloaded, and
> which are working in my GNU, but noisy( only ssb_rx is noisy and sstx1 is not
> working)
>






> _______________________________________________
> Discuss-gnuradio mailing list
> Discuss-gnuradio@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio


--
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin Braun
Research Associate

Kaiserstraße 12
Building 05.01
76131 Karlsruhe

Phone: +49 721 608-43790
Fax: +49 721 608-46071
www.cel.kit.edu

KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association
03d96e38f7592042a54ebf4760d069c0?d=identicon&s=25 Bijendra Singh (Guest)
on 2013-10-10 10:40
(Received via mailing list)
Well it is a project I'm working on. I am trying to receive an AM signal
from HF radio which will be provided in the usrp source in my gnu and
will
transmit a FM signal as output in the usrp sink which I'm trying to send
it
to the VHF radio. And vice versa. I'm using CNR-900 VHF radio which freq
range is 30 to 89.899 MHz and RS-HX radio which freq range is 3 to 30
MHz.
When I tried the hf2vhf.grc file, it is working, but with noise. Same
thing
will be possible for VHF to Hf, I guess. And I'm stuck in this. Any
possible remedies??
7d89a70df32c0ae27c1235016f9e5441?d=identicon&s=25 "Marcus Müller" <marcus@hostalia.de> (Guest)
on 2013-10-10 12:06
(Received via mailing list)
Hi Bijendra,
I, too, am confused.
So let's try to understand what you are doing here!
On 10/10/2013 10:39 AM, Bijendra Singh wrote:
> Well it is a project I'm working on.
> I am trying to receive an AM signal from HF radio
Yes, so receiving amplitude modulated audio on a carrier somewhere
between 3MHz and 30Mhz (==HF)
> which will be provided in the usrp source in my gnu
You want to capture that using a USRP and GNU Radio, I presume.
> and will transmit a FM signal as output
Aaaaha! Second chain of operation! You want to simultaneously generate
an FM signal
> in the usrp sink which I'm trying to send it to the VHF radio.
And you want to transmit that using a USRP (the same USRP?) to another
Radio receiver, that listens on a VHF carrier (30MHz-300MHz) then.
> And vice versa.
Huh? Your radio receivers usually can't transmit, so that's confusing
> I'm using CNR-900 VHF radio which freq range is 30 to 89.899 MHz and RS-HX radio
which freq range is 3 to 30 MHz. When I tried the hf2vhf.grc file, it is 
working,
but with noise. Same thing will be possible for VHF to Hf, I guess. And I'm 
stuck
in this. Any possible remedies??
>
OOooooh ok... this is military communications, and I was under the
impression we're talking broadcast Radio stations.
I must try to reunderstand now:
You're trying to set up a relay station, for someone with some kind of
HF AM tactical radio to communicate with someone with a VHF FM tactical
radio, right?
Anyway, Martin is right: Whatever you do, AM will always be noisy
because it's AM, and unless you use laaarge antennas the HF signal on
the USRP will most probably be strongly attenuated (1/2 wavelength of
30MHz is 5m...). So your SNR gets even worse.

Greetings,
Marcus
7d89a70df32c0ae27c1235016f9e5441?d=identicon&s=25 "Marcus Müller" <marcus@hostalia.de> (Guest)
on 2013-10-11 07:57
(Received via mailing list)
Hi Bijendra,

I'm under the expression that Wayne has already supplied you with the
idea of the AM tx flowgraph; it's your project, clicking together the
flowgraph after his description is up to you ;)

Well, if you need full-duplex, you will need two independent RX and two
independent TX radio interfaces, so you need to have two USRP sources,
two USRP sinks, and connect everything correctly.

Again: AM Rx will always be noisy as long as you don't do stunts on the
analog/physical side of your receiver; I haven't had a look at your GRC
files though, so is it possible you don't low pass your received signal?
AM transmission seldom have a bandwidth significantly higher than 3kHz;
this is partly because usually analog AM receivers have quite narrowband
RF filters, to avoid picking up a lot of noise. Since this is totally
anti-software defined radio, the LFRX doesn't have such filters.
Get a filter, get a preamp, get a higher gain antenna. Do what you must
do to get a cleaner signal.

Happy hacking,
Marcus
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