Building a (cheap) software radio

I am trying to build a software radio with a budget of about $60, but I
don't really know what to get. If I got it right (correct me if i'm
wrong), I need an antenna, something to amplify the signal, something
to filter the band, something to downsample, and something with a
bandwidth big enough (200 kHz i think) to be able to get FM

The problem is that I have no idea in any of this on what I should buy,
nor even where I should buy it, besides that I might get a TV tuner
card because they have a wide input bandwidth, but then I don't know
how wide it can be, and then I wouldn't know which card I should buy.

PS : Please do not point me to any GnuRadio page, cuz i've already read
it all many times, and don't advise me to buy some $600 ADC, thanks

You might get some joy by using an FM tuner and digitizing the 10.7MHz
IF output.  You would however lose the ability to tune it in software.

Interesting project.  The ultimate would be a single TQFP postage stamp
with a pin each for the power, antenna, speakers and control
pushbuttons.

Jim A.

Michel Rouzic wrote:
> I am trying to build a software radio with a budget of about $60, but I
> don't really know what to get. If I got it right (correct me if i'm
> wrong), I need an antenna, something to amplify the signal, something
> to filter the band, something to downsample, and something with a
> bandwidth big enough (200 kHz i think) to be able to get FM
> 
> The problem is that I have no idea in any of this on what I should buy,
> nor even where I should buy it, besides that I might get a TV tuner
> card because they have a wide input bandwidth, but then I don't know
> how wide it can be, and then I wouldn't know which card I should buy.
> 
> PS : Please do not point me to any GnuRadio page, cuz i've already read
> it all many times, and don't advise me to buy some $600 ADC, thanks

Your best option if you do only want to receive FM is to use a standard 
FM receiver, remove the IF filter, replace it with a wider filter, and 
then tap the output off to your ADC of choice.
The ADC will be much cheaper than $600, probably more like $10.  But you 
would need to make up a PCB etc to house it, and some processor to 
demodulate the FM signals.

Not the best project to attempt unless you've got quite a bit of 
experience with electronics in general.  It's very unlikely you'd get it 
to work as desired without quite an indepth knowledge of electronics.

I recall GnuRadio advising the use of a particular receiver board, I 
think they even made it available for order via the Internet or some 
such.  If you just care about the software side of things, then this 
would be the most economical option (if your time is worth anything 
anyways).

"Michel Rouzic" <Michel0528@yahoo.fr> wrote in message 
news:1133090382.299016.154370@g47g2000cwa.googlegroups.com...
>I am trying to build a software radio with a budget of about $60, but I
> don't really know what to get. If I got it right (correct me if i'm
> wrong), I need an antenna, something to amplify the signal, something
> to filter the band, something to downsample, and something with a
> bandwidth big enough (200 kHz i think) to be able to get FM
>
> The problem is that I have no idea in any of this on what I should buy,
> nor even where I should buy it, besides that I might get a TV tuner
> card because they have a wide input bandwidth, but then I don't know
> how wide it can be, and then I wouldn't know which card I should buy.
>
> PS : Please do not point me to any GnuRadio page, cuz i've already read
> it all many times, and don't advise me to buy some $600 ADC, thanks

$60 ?

I take it you mean a software radio reciever ?

How much has to be in software ?

What sort of radio signal ?

Could try doing it all in an fpga
and use the input as a adc or is that in virtex4 only ?

Virtex only
http://direct.xilinx.com/bvdocs/appnotes/xapp154.pdf
http://direct.xilinx.com/bvdocs/appnotes/xapp155.pdf

spartan3 starter kits from xilinx are available for US$99
<http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?sGlobalNavPick=PRODUCTS&sSecondaryNavPick=Design+Tools&category=&iLanguageID=1&key=DO-SPAR3-DK>
http://www.xilinx.com/products/boards/DO-SPAR3-DK/reference_designs.htm

Maybe one of the micros with builtin 1Msps+ adc
one of the silabs 8051's or analog 8051's or arm7 chips

Alex 

Jim Adamthwaite wrote:
> You might get some joy by using an FM tuner and digitizing the 10.7MHz
> IF output.  You would however lose the ability to tune it in software.
>
> Interesting project.  The ultimate would be a single TQFP postage stamp
> with a pin each for the power, antenna, speakers and control
> pushbuttons.
>
> Jim A.

I'm not looking for receiving only FM actually. I mentionned the FM
thing cuz I know that due to the bandwidth it takes you gotta take that
in consideration before you buy anything.

A single TQFP postage stamp? I just googled TQFP and it seems like it's
a chip, but what is it for?

Bevan Weiss wrote:
> Your best option if you do only want to receive FM is to use a standard
> FM receiver, remove the IF filter, replace it with a wider filter, and
> then tap the output off to your ADC of choice.

Interesting option, however I'm not looking forward only receiving FM,
and then I don't think I would even know what to remove in some FM
receiver.

> The ADC will be much cheaper than $600, probably more like $10.  But you
> would need to make up a PCB etc to house it, and some processor to
> demodulate the FM signals.

A PCB? Printed Circuit Board? to house an ADC? *scratches head* I
thought that some computer audio input or some tv tuner input would be
sufficient, depending on the bandwidth needed. And some processor to
demodulate the FM signals? I thought that it would be the software's
job, like GnuRadio is supposed to do.

> Not the best project to attempt unless you've got quite a bit of
> experience with electronics in general.  It's very unlikely you'd get it
> to work as desired without quite an indepth knowledge of electronics.

Um... my experience with electronics consisted pretty much of putting
in pieces everything I could get my hands on when I was 12, besides
that, ain't got much experience. And from what I think i understood, I
just thought I'd have to buy the right hardware and put it together..
you make me confused

> I recall GnuRadio advising the use of a particular receiver board, I
> think they even made it available for order via the Internet or some
> such.  If you just care about the software side of things, then this
> would be the most economical option (if your time is worth anything
> anyways).

Please, tell me you're not talking about the Universal Software Radio
Peripherial, only the motherboard costs $550, i'm ok to spend up to
$100 on this project, but not $550 just for that (not even talking
about the daughterboards).

My motivation in doing this is pretty much getting some simple hardware
which I can easily understand the function and getting as an input some
un-demodulated signal that I can deal with, with already existing
software like GnuRadio or even by writing my own, I'm pretty much
looking for the fun, educational and explanative side of all that you
know, so I guess I'd like to avoid such thing as the USRP anyways.

I'm just looking forward information on what hardware I need in order
to get signals in my computer, no matter whether it's AM, FM, SSB or
morse.

Alex Gibson wrote:
> $60 ?

It could be $100.. at most..

> I take it you mean a software radio reciever ?

yup

> How much has to be in software ?

?? in case you're talking about money, $0.00.

> What sort of radio signal ?

AM, FM, SSB, why not TV too, nothing precise

> Could try doing it all in an fpga
> and use the input as a adc or is that in virtex4 only ?
>
> Virtex only
> http://direct.xilinx.com/bvdocs/appnotes/xapp154.pdf
> http://direct.xilinx.com/bvdocs/appnotes/xapp155.pdf
>
> spartan3 starter kits from xilinx are available for US$99
> <http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?sGlobalNavPick=PRODUCTS&sSecondaryNavPick=Design+Tools&category=&iLanguageID=1&key=DO-SPAR3-DK>
> http://www.xilinx.com/products/boards/DO-SPAR3-DK/reference_designs.htm
>
> Maybe one of the micros with builtin 1Msps+ adc
> one of the silabs 8051's or analog 8051's or arm7 chips

*scratches head again* I thought you guys would advise me a good type
of antenna, some amplifier, some TV tuner card as an ADC, but all I
hear about is chips.

I just thought I'd need something like an antenna, an amplifier, some
kind of analog band-pass filter, and some ADC, and I thought you guys
would point out if something was lacking or not being necessary, and
advise me on what I should buy...

Michel Rouzic wrote:
> Jim Adamthwaite wrote:
> 
>>You might get some joy by using an FM tuner and digitizing the 10.7MHz
>>IF output.  You would however lose the ability to tune it in software.
>>
>>Interesting project.  The ultimate would be a single TQFP postage stamp
>>with a pin each for the power, antenna, speakers and control
>>pushbuttons.
>>
>>Jim A.
> 
> 
> I'm not looking for receiving only FM actually. I mentionned the FM
> thing cuz I know that due to the bandwidth it takes you gotta take that
> in consideration before you buy anything.
> 

A digital general purpose radio for $60 is very ambitious. I'm not saying
it can't be done, especially if you don't consider the cost of the PC, but
you're likely to pay at least $100 for a bare printed circuit board you
will design.

The trick is to downconvert to an IF that a high end PC audio input can
process. I've heard that some ADCs on some audio chips can run up to
200 K samples/s. That's where going back to GNU Radio and reading up
will serve you, even if you don't use a single scrap of code from them.

> A single TQFP postage stamp? I just googled TQFP and it seems like it's
> a chip, but what is it for?
> 

He was talking about a (non-existent) single chip all digital (perhaps)
radio, something that is maybe a few years away. But at that point,
what's the fun?

I'm in the thinking stage of such a project, but I want to build an
all digital unit. By all digital, that means no IF, just really fast
digitizing of the signal, and then digital processing after that.
It can be done, but it is difficult, and I guess the budget needs to
start at about 5000 US$ just for parts and boards. But that's not the
same thing as starting from IF, of course.

Michel Rouzic wrote:
> Alex Gibson wrote:
> 
>>$60 ?
> 
> 
> It could be $100.. at most..
> 
> 
[...]
>>
>>Virtex only
>>http://direct.xilinx.com/bvdocs/appnotes/xapp154.pdf
>>http://direct.xilinx.com/bvdocs/appnotes/xapp155.pdf
>>
>>spartan3 starter kits from xilinx are available for US$99
>><http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?sGlobalNavPick=PRODUCTS&sSecondaryNavPick=Design+Tools&category=&iLanguageID=1&key=DO-SPAR3-DK>
>>http://www.xilinx.com/products/boards/DO-SPAR3-DK/reference_designs.htm
>>
>>Maybe one of the micros with builtin 1Msps+ adc
>>one of the silabs 8051's or analog 8051's or arm7 chips
> 
> 
> *scratches head again* I thought you guys would advise me a good type
> of antenna, some amplifier, some TV tuner card as an ADC, but all I
> hear about is chips.
> 

No such thing exists as an off the shelf product. If it did, it would
probably sell, but that's what the USRP is all about - it's just too
expensive for your bugdet.

PCs are not fast enough to demodulate IF, so all these peripherals (radio
and TV cards for PCs) present you with baseband, and there is no opportunity
to demodulate anything.

If you can get an IF low enough, that's where the possibilities open up
for using a PC.

> I just thought I'd need something like an antenna, an amplifier, some
> kind of analog band-pass filter, and some ADC, and I thought you guys
> would point out if something was lacking or not being necessary, and
> advise me on what I should buy...
> 

"Bevan Weiss" <kaizen__@NOSPAM.hotmail.com> wrote in message
news:mxhif.3972$vH5.223504@news.xtra.co.nz...
> Michel Rouzic wrote:
> > I am trying to build a software radio with a budget of about $60, but I
> > don't really know what to get. If I got it right (correct me if i'm
> > wrong), I need an antenna, something to amplify the signal, something
> > to filter the band, something to downsample, and something with a
> > bandwidth big enough (200 kHz i think) to be able to get FM
> >
> > The problem is that I have no idea in any of this on what I should buy,
> > nor even where I should buy it, besides that I might get a TV tuner
> > card because they have a wide input bandwidth, but then I don't know
> > how wide it can be, and then I wouldn't know which card I should buy.
> >
> > PS : Please do not point me to any GnuRadio page, cuz i've already read
> > it all many times, and don't advise me to buy some $600 ADC, thanks
>
> Your best option if you do only want to receive FM is to use a standard
> FM receiver, remove the IF filter, replace it with a wider filter, and
> then tap the output off to your ADC of choice.
> The ADC will be much cheaper than $600, probably more like $10.  But you
> would need to make up a PCB etc to house it, and some processor to
> demodulate the FM signals.
>
> Not the best project to attempt unless you've got quite a bit of
> experience with electronics in general.  It's very unlikely you'd get it
> to work as desired without quite an indepth knowledge of electronics.
>
> I recall GnuRadio advising the use of a particular receiver board, I
> think they even made it available for order via the Internet or some
> such.  If you just care about the software side of things, then this
> would be the most economical option (if your time is worth anything
> anyways).

I have this board - it's quite good but the trouble is that the software is
written in Python and all things Linux!
It took me two weeks in one operating sysytem to load most of it and I still
had errors. Then I switched to another linux OS and wasted anotehr two weeks
(full time!). There is a newsgroup email thing that is useful but in my
opnion it's a bit of a nightmare.

McC