anyone use SDRs?

i am looking at the Ciaoradio. it is 349 Euros, and i think it comes with
the software. i may invest in the software alone at first.

i would like an RFspace SDR, because it can record 160 khz band to hard
drive. both that and the Gnuradio hardware are too expensive.

i am using my sound card for DC to 22 khz reception.

my Sony ICF2001 is doing poorly. i suspect there is corrosion in the
potentiometers. and i may have blown out the front end somehow. i hear you
can mess up a front end and the radio will still work, but you can't hear
much of anything.

my choices now a

1. repair the Yaesu transceiver
2. use the Yaesu FRG7 receiver
3. get a Sangean or Ciaoradio
4. focus on ELF with an Maudio card

i'd love to have an SDR, but i still want to decode RTTY and do other
things. so a gen purpose receiver may be easiest.

Gravity

Have ya looked at WinRadio's line?

"gravity" wrote in message
reenews.net...
anyone use SDRs?

i am looking at the Ciaoradio. it is 349 Euros, and i think it comes with
the software. i may invest in the software alone at first.

i would like an RFspace SDR, because it can record 160 khz band to hard
drive. both that and the Gnuradio hardware are too expensive.

i am using my sound card for DC to 22 khz reception.

my Sony ICF2001 is doing poorly. i suspect there is corrosion in the
potentiometers. and i may have blown out the front end somehow. i hear
you
can mess up a front end and the radio will still work, but you can't hear
much of anything.

my choices now a

1. repair the Yaesu transceiver
2. use the Yaesu FRG7 receiver
3. get a Sangean or Ciaoradio
4. focus on ELF with an Maudio card

i'd love to have an SDR, but i still want to decode RTTY and do other
things. so a gen purpose receiver may be easiest.

Gravity

gravity wrote:
anyone use SDRs?

i am looking at the Ciaoradio. it is 349 Euros, and i think it comes with
the software. i may invest in the software alone at first.

i would like an RFspace SDR, because it can record 160 khz band to hard
drive. both that and the Gnuradio hardware are too expensive.

i am using my sound card for DC to 22 khz reception.

my Sony ICF2001 is doing poorly. i suspect there is corrosion in the
potentiometers. and i may have blown out the front end somehow. i hear you
can mess up a front end and the radio will still work, but you can't hear
much of anything.

my choices now a

1. repair the Yaesu transceiver
2. use the Yaesu FRG7 receiver
3. get a Sangean or Ciaoradio
4. focus on ELF with an Maudio card

i'd love to have an SDR, but i still want to decode RTTY and do other
things. so a gen purpose receiver may be easiest.

Gravity

I think analog front end and RF DSP demo is the way to go. I wish the
market would work more on such a product. I don't consider DSP in the
analog to be the solution. I'd like to see a FFT panoramic display in
the radio, or at least a port to feed it to a PC.

wrote:
So I could make a short wave radio out of a laptop
using this software?

You can make an Extremely Low Frequency radio out of a computer,
tunable across the bandwidth of its sound system. You could tune up to
about 1/2 the sampling frequency of the sound systems analog-to-digital
converter. Typical sample rates are 48kHz but high end systems go up to
192 kHz so the tuning range would be up to 24 kHz and 96 kHz
respectively, provided the computer can execute the SDR DSP software
fast enough. If you connected an antenna to the microphone input, you
might hear something. To tune higher frequencies, you can use a
conventional superhet receiver as a tunable downconverter, connecting
its last IF (if higher than the computer's audio input range) to a
fixed downconverter, e.g., from 455 kHz to 12 kHz.

Some radios, like the DX-394, can be readily modified to integrate the
fixed downconverter or attach it externally. And there are exceptional
radios that already include a 12 kHz IF output ready to be plugged into
the computer.

I have had great fun using the DX-394 with Dream and SDRadio software
demodulators. The performance on SW-AM broadcasts and SSB is truly
remarkable because of the steep-skirted IF filter and synchronous AM
demodulation.

Tom

Tom wrote:
wrote:
So I could make a short wave radio out of a laptop
using this software?

You can make an Extremely Low Frequency radio out of a computer,
tunable across the bandwidth of its sound system. You could tune up to
about 1/2 the sampling frequency of the sound systems analog-to-digital
converter. Typical sample rates are 48kHz but high end systems go up to
192 kHz so the tuning range would be up to 24 kHz and 96 kHz
respectively, provided the computer can execute the SDR DSP software
fast enough. If you connected an antenna to the microphone input, you
might hear something. To tune higher frequencies, you can use a
conventional superhet receiver as a tunable downconverter, connecting
its last IF (if higher than the computer's audio input range) to a
fixed downconverter, e.g., from 455 kHz to 12 kHz.


Err, Ummm, well, yeah, in THEORY you could. In practice you'll need to
decouple your computer from the antenna pretty well. This means you'll
need a very high Q antenna with a very low noise amplifier to isolate
it, and a very well isolated DC supply to power the amplifier. If those
things exist, you can build your very own VLF receiver from a sound
card. In fact, if your sound card can manage a sample rate of at least
120 kSamples/second then you could use it to tune in WWVB at 60 kHz or
perhaps the German equivalent at 77 kHz if you can manage to sample at
twice that rate.

Other than WWVB, I don't think much is still down there. The earth's
ionosphere resonates at about 7 Hz if memory serves, so that might be a
lower limit to what you might want to try monitoring. The Omega system
was decommissioned years ago, though I've heard rumors that some parts
of it might still be in service in some corners of the world. Finally,
if there are any old FDM coaxial systems nearby, you might detect some
leakage from their traffic (I doubt there are any who still use this
method to trunk VF traffic together, but if there are a few, you might
still hear it)

And yes, a very few radios have a third IF at 50 kHz which you could use
such a sound card with. That experiment has potential.

73,

Jake Brodsky
Amateur Radio Station AB3A

Jake Brodsky wrote:
Tom wrote:
wrote:
So I could make a short wave radio out of a laptop
using this software?

You can make an Extremely Low Frequency radio out of a computer,
tunable across the bandwidth of its sound system. You could tune up to
about 1/2 the sampling frequency of the sound systems analog-to-digital
converter. Typical sample rates are 48kHz but high end systems go up to
192 kHz so the tuning range would be up to 24 kHz and 96 kHz
respectively, provided the computer can execute the SDR DSP software
fast enough. If you connected an antenna to the microphone input, you
might hear something. To tune higher frequencies, you can use a
conventional superhet receiver as a tunable downconverter, connecting
its last IF (if higher than the computer's audio input range) to a
fixed downconverter, e.g., from 455 kHz to 12 kHz.


Err, Ummm, well, yeah, in THEORY you could. In practice you'll need to
decouple your computer from the antenna pretty well. This means you'll
need a very high Q antenna with a very low noise amplifier to isolate
it, and a very well isolated DC supply to power the amplifier. If those
things exist, you can build your very own VLF receiver from a sound
card. In fact, if your sound card can manage a sample rate of at least
120 kSamples/second then you could use it to tune in WWVB at 60 kHz or
perhaps the German equivalent at 77 kHz if you can manage to sample at
twice that rate.

Other than WWVB, I don't think much is still down there. The earth's
ionosphere resonates at about 7 Hz if memory serves, so that might be a
lower limit to what you might want to try monitoring. The Omega system
was decommissioned years ago, though I've heard rumors that some parts
of it might still be in service in some corners of the world. Finally,
if there are any old FDM coaxial systems nearby, you might detect some
leakage from their traffic (I doubt there are any who still use this
method to trunk VF traffic together, but if there are a few, you might
still hear it)

And yes, a very few radios have a third IF at 50 kHz which you could use
such a sound card with. That experiment has potential.

73,

Jake Brodsky
Amateur Radio Station AB3A

Yeah, everything looks easy in theory. Computers are serious noise
machines.

You've probably seen this website:
http://www.vlf.it/

Think of painting a room. Isn't 90% of the work the preparation? Well,
in signal analysis, conditioning the signal is a serious chunk of the
work. Once you have something clean, then digital analysis can be done.


If you do build any of those designs on vlf.it, you may want to
investigate better (lower noise) op amps.

Jake Brodsky wrote:
Tom wrote:
wrote:
So I could make a short wave radio out of a laptop
using this software?

You can make an Extremely Low Frequency radio out of a computer,
tunable across the bandwidth of its sound system. You could tune up to
about 1/2 the sampling frequency of the sound systems analog-to-digital
converter. Typical sample rates are 48kHz but high end systems go up to
192 kHz so the tuning range would be up to 24 kHz and 96 kHz
respectively, provided the computer can execute the SDR DSP software
fast enough. If you connected an antenna to the microphone input, you
might hear something. To tune higher frequencies, you can use a
conventional superhet receiver as a tunable downconverter, connecting
its last IF (if higher than the computer's audio input range) to a
fixed downconverter, e.g., from 455 kHz to 12 kHz.


Err, Ummm, well, yeah, in THEORY you could. In practice you'll need to
decouple your computer from the antenna pretty well. This means you'll
need a very high Q antenna with a very low noise amplifier to isolate
it, and a very well isolated DC supply to power the amplifier. If those
things exist, you can build your very own VLF receiver from a sound
card. In fact, if your sound card can manage a sample rate of at least
120 kSamples/second then you could use it to tune in WWVB at 60 kHz or
perhaps the German equivalent at 77 kHz if you can manage to sample at
twice that rate.

[snip]
And yes, a very few radios have a third IF at 50 kHz which you could use
such a sound card with. That experiment has potential.

73,

Jake Brodsky
Amateur Radio Station AB3A

The point of my message was that you cannot make a SW radio out of a
laptop alone ( the question he asked) but could make a VLF receiver out
of a laptop that could be used with a downconverter to tune SW. Many
have done so. The downconverter is typically a superhet radio whose
last IF is downconverted through an add-on to the audio frequency
range.

The audio frequency laptop receiver need not have especially high
sampling frequency or sample size when used with a downconverter for
SW. A 10 kHz wide passband is adequate for most transmission modes and
is readily provided by a 48 kHz sample rate - even 24 kHz could be
enough. Because the front end tuner has AGC and can regulate levels
into the sound card, the latter's A/D converter having something
approaching 16 bit resolution will have more than adequate dynamic
range - even 8-bits could be sufficient.

Of course, the state of the art is for higher resolution A/D converters
and higher sampling rates for direct conversion for DSP. As discussed
elsewhere, great care must be taken in controlling interference from
the SDR to itself, via the antenna or other unintended coupling.

Tom

gravity wrote:

it might make more sense to buy an off the shelf solution e.g. Ciaoradio,
RFspace, or Gnu Radio. however it would be cool to homebrew the whole
thing!

Gravity

73,

Jake Brodsky
Amateur Radio Station AB3A

Gravity, you really bring me down.

"Tom" wrote:

The point of my message was that you cannot make a SW radio out of a
laptop alone

yes that was my question

And now I'm clear on that...thanks!

I've just been debating buying a small portable SW
radio as I've gotten completely rid of TV and cable TV
and thinking maybe SW radio might be a good replacement
for it.

Sounds like it best for me to get a dedicated stand
lone small SW radio

I mistakenly assumed I could put some software on my
laptop and make a SW radio out it

wrote:
I've just been debating buying a small portable SW
radio as I've gotten completely rid of TV and cable TV
and thinking maybe SW radio might be a good replacement
for it.

Sounds like it best for me to get a dedicated stand
lone small SW radio

I mistakenly assumed I could put some software on my
laptop and make a SW radio out it

Well, SW is no equivalent to TV but it can be entertaining and
educational, in different ways. If you post a message requesting advice
on selecting a radio, you'll get lots! For not a lot of money, I would
suggest the Degen DE1103/Kaito KA1103 or the more attractive Eton E5,
all from the same factory with much in common, and in ascending order
of price.

Good luck!

Tom