Advise for amateur RF software projects

In my endless quest to acquire measurement hardware for cheap, I ended
up with a piece of hardware which I can't see how I will use it.  Most
of the work I do on the job involves displacement, acceleration and
sound pressure measurement up to 100kHz.  

I thought it would be fun to refurbish a cPCI based FPGA development
system with a host controller that I saw (and bought) from eBay.   I
guess in retrospect this might have been a mistake but I did only
invest a few hundred dollars in it.  Now that the system is all
working to specifications I find out the ADC has an input filter which
restricts the minimum frequency to 400kHz.  Oops.  

The actual specification is, 8 channels simultaneously sampled, 0.4MHz
to 204MHz, 0 to 22dBm with a PGA which extends the range.  The output
is 6 channels, simultaneously sampled, DC to 1MHz 0 to 10V.  Both feed
into/out of a Vertex-4 SX55 FPGA, this is the DSP block heavy version.
I bought the thing because it supported model based development from
Simulink and had a pretty well developed host interface and full
source for the FPGA.

So, after that long preamble, my question is.  Does anyone have some
suggestions for an amateur radio or other HF projects which I might
play around with in my spare time?  I did some searching on the
internet and have not come up with anything yet.  After I put so much
time into rounding up software and parts I hate to waste this system
by just putting it back on eBay.  The only thing I can come up with so
far is making an AM/FM software tuner.  My idea of RF is kind of rusty
since the last time I even thought about it was at the University
class.

Mark DeArman

Mac Decman <dearman.mark@gmail.com> wrote:

(snip)
> I thought it would be fun to refurbish a cPCI based FPGA development
> system with a host controller that I saw (and bought) from eBay.   I
> guess in retrospect this might have been a mistake but I did only
> invest a few hundred dollars in it.  Now that the system is all
> working to specifications I find out the ADC has an input filter which
> restricts the minimum frequency to 400kHz.  Oops.  

(snip)

> So, after that long preamble, my question is.  Does anyone have some
> suggestions for an amateur radio or other HF projects which I might
> play around with in my spare time?  I did some searching on the
> internet and have not come up with anything yet.  After I put so much
> time into rounding up software and parts I hate to waste this system
> by just putting it back on eBay.  The only thing I can come up with so
> far is making an AM/FM software tuner.  

I will disagree with your use of the term 'software' in 
describing what is implemented in an FPGA, but otherwise
that is about what I would have thought up.

> My idea of RF is kind of rusty since the last time I even 
> thought about it was at the University class.

-- glen

On Wed, 24 Oct 2012 08:42:06 +0000 (UTC), glen herrmannsfeldt
<gah@ugcs.caltech.edu> wrote:

>Mac Decman <dearman.mark@gmail.com> wrote:
>
(snip)
>I will disagree with your use of the term 'software' in 
>describing what is implemented in an FPGA, but otherwise
>that is about what I would have thought up.

Well by software I was talking about the host parts.  VHDL, drivers,
synth components, flash utilities, etc.

>> My idea of RF is kind of rusty since the last time I even 
>> thought about it was at the University class.
>
>-- glen

On Wed, 24 Oct 2012 02:00:20 -0700, Mac Decman
<dearman.mark@gmail.com> wrote:

>On Wed, 24 Oct 2012 08:42:06 +0000 (UTC), glen herrmannsfeldt
><gah@ugcs.caltech.edu> wrote:
>
>>Mac Decman <dearman.mark@gmail.com> wrote:
>>
>(snip)
>>I will disagree with your use of the term 'software' in 
>>describing what is implemented in an FPGA, but otherwise
>>that is about what I would have thought up.
>
>Well by software I was talking about the host parts.  VHDL, drivers,
>synth components, flash utilities, etc.
>
>>> My idea of RF is kind of rusty since the last time I even 
>>> thought about it was at the University class.
>>
>>-- glen

oops, nix that one, I misread your reply.  Yes, I disagree with
'software' in FPGA too ;-)  My mistake in the post.  I got the SDR
acronym too stuck in my head.

Mark DeArman

On 24.10.12 11:32 , Mac Decman wrote:
> In my endless quest to acquire measurement hardware for cheap, I ended
> up with a piece of hardware which I can't see how I will use it.  Most
> of the work I do on the job involves displacement, acceleration and
> sound pressure measurement up to 100kHz.
>
> I thought it would be fun to refurbish a cPCI based FPGA development
> system with a host controller that I saw (and bought) from eBay.   I
> guess in retrospect this might have been a mistake but I did only
> invest a few hundred dollars in it.  Now that the system is all
> working to specifications I find out the ADC has an input filter which
> restricts the minimum frequency to 400kHz.  Oops.
>
> The actual specification is, 8 channels simultaneously sampled, 0.4MHz
> to 204MHz, 0 to 22dBm with a PGA which extends the range.  The output
> is 6 channels, simultaneously sampled, DC to 1MHz 0 to 10V.  Both feed
> into/out of a Vertex-4 SX55 FPGA, this is the DSP block heavy version.
> I bought the thing because it supported model based development from
> Simulink and had a pretty well developed host interface and full
> source for the FPGA.
>
> So, after that long preamble, my question is.  Does anyone have some
> suggestions for an amateur radio or other HF projects which I might
> play around with in my spare time?  I did some searching on the
> internet and have not come up with anything yet.  After I put so much
> time into rounding up software and parts I hate to waste this system
> by just putting it back on eBay.  The only thing I can come up with so
> far is making an AM/FM software tuner.  My idea of RF is kind of rusty
> since the last time I even thought about it was at the University
> class.
>
> Mark DeArman
>


For amateur RF projects, there is no substitute to the ARRL handbook.
It contains plenty of good leads when you have determined the direction
you want to go. Also, there is a solid RF basics foundation.

-- 

Tauno Voipio, OH2UG

On Wed, 24 Oct 2012 02:07:56 -0700, Mac Decman wrote:

> On Wed, 24 Oct 2012 02:00:20 -0700, Mac Decman <dearman.mark@gmail.com>
> wrote:
> 
>>On Wed, 24 Oct 2012 08:42:06 +0000 (UTC), glen herrmannsfeldt
>><gah@ugcs.caltech.edu> wrote:
>>
>>>Mac Decman <dearman.mark@gmail.com> wrote:
>>>
>>(snip)
>>>I will disagree with your use of the term 'software' in describing what
>>>is implemented in an FPGA, but otherwise that is about what I would
>>>have thought up.
>>
>>Well by software I was talking about the host parts.  VHDL, drivers,
>>synth components, flash utilities, etc.
>>
>>>> My idea of RF is kind of rusty since the last time I even thought
>>>> about it was at the University class.
>>>
>>>-- glen
> 
> oops, nix that one, I misread your reply.  Yes, I disagree with
> 'software' in FPGA too ;-)  My mistake in the post.  I got the SDR
> acronym too stuck in my head.
> 
> Mark DeArman

"SDR" seems to be applied to radios that are primarily defined by FPGA 
firmware.

I think we just need to live with the fact that the terms "firmware" and 
"software" are gonna overlap (and, for that matter, "firmware" and 
"hardware" is going to overlap a bit, too).

-- 
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

On Wed, 24 Oct 2012 01:32:19 -0700, Mac Decman wrote:

> In my endless quest to acquire measurement hardware for cheap, I ended
> up with a piece of hardware which I can't see how I will use it.  Most
> of the work I do on the job involves displacement, acceleration and
> sound pressure measurement up to 100kHz.
> 
> I thought it would be fun to refurbish a cPCI based FPGA development
> system with a host controller that I saw (and bought) from eBay.   I
> guess in retrospect this might have been a mistake but I did only invest
> a few hundred dollars in it.  Now that the system is all working to
> specifications I find out the ADC has an input filter which restricts
> the minimum frequency to 400kHz.  Oops.
> 
> The actual specification is, 8 channels simultaneously sampled, 0.4MHz
> to 204MHz, 0 to 22dBm with a PGA which extends the range.  The output is
> 6 channels, simultaneously sampled, DC to 1MHz 0 to 10V.  Both feed
> into/out of a Vertex-4 SX55 FPGA, this is the DSP block heavy version. I
> bought the thing because it supported model based development from
> Simulink and had a pretty well developed host interface and full source
> for the FPGA.
> 
> So, after that long preamble, my question is.  Does anyone have some
> suggestions for an amateur radio or other HF projects which I might play
> around with in my spare time?  I did some searching on the internet and
> have not come up with anything yet.  After I put so much time into
> rounding up software and parts I hate to waste this system by just
> putting it back on eBay.  The only thing I can come up with so far is
> making an AM/FM software tuner.  My idea of RF is kind of rusty since
> the last time I even thought about it was at the University class.
> 
> Mark DeArman

Is there any radio in particular that you want to build?  If so, perhaps 
you could start there and see if your hardware will support it.

Are you saying that the ADC filter restricts the _minimum_ frequency?  
I.e., it's a high-pass?  If so, then you're in hog heaven from an RF 
point of view.  And if you really want to go lower, you may be able to 
modify the filters for a lower cutoff.

It looks like you have the RF resources to do a full-featured HF-band 
radio, although you may be disappointed by its small-signal performance 
because of spurs from the PC: you'd pretty much have to experiment to see.

-- 
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

one typical FPGA application is predistortion for RF power amplifiers, if
you have ADCs and DACs that can handle a reasonable intermediate frequency.


It is possible to "bootstrap" such a project without high-end measurement
equipment - use memory to stream and record data, and do the processing
initially offline. But it will be quite a big project, even with a clear
understanding of the algorithms involved.

On Wed, 24 Oct 2012 11:50:04 -0500, mnentwig wrote:

> one typical FPGA application is predistortion for RF power amplifiers,
> if you have ADCs and DACs that can handle a reasonable intermediate
> frequency.
> 
> 
> It is possible to "bootstrap" such a project without high-end
> measurement equipment - use memory to stream and record data, and do the
> processing initially offline. But it will be quite a big project, even
> with a clear understanding of the algorithms involved.

Yup.  It'll keep you out of trouble for months.

I had a client doing some specialized cell phone stuff that used an ADC 
card to stream to disk, then did solutions off-line.  They were going 
after "side" information rather than needing fully functional cell-phone 
conversations, so they didn't need to do things in real-time.  My 
deliverables to them were Scilab prototypes and C++ code that they 
integrated into their larger application.

It was an inneresting project, to be sure.  I would have liked to have 
been involved in a whole SDR project -- maybe someday.

-- 
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

Tim Wescott <tim@seemywebsite.com> wrote:

(snip, I wrote)
>>>>I will disagree with your use of the term 'software' in describing what
>>>>is implemented in an FPGA, but otherwise that is about what I would
>>>>have thought up.

>>>Well by software I was talking about the host parts.  VHDL, drivers,
>>>synth components, flash utilities, etc.

(snip)
>> oops, nix that one, I misread your reply.  Yes, I disagree with
>> 'software' in FPGA too ;-)  My mistake in the post.  I got the SDR
>> acronym too stuck in my head.

> "SDR" seems to be applied to radios that are primarily defined by FPGA 
> firmware.

As I understand it, the earlier ones were done at lower frequencies
on DSP, and so were software (or firmware if in EPROM). 

At higher frequencies, it is usually done in FPGAs, programmable
hardware. 

One reason for noting the difference is that the thought process
for writing verilog is that of digital hardware (gates and flip-flops)
not software (if-then and for loops). 

> I think we just need to live with the fact that the terms "firmware" and 
> "software" are gonna overlap (and, for that matter, "firmware" and 
> "hardware" is going to overlap a bit, too).

I suppose. Firmware is usually used to describe software that
doesn't change so easily. When it was in ROM or EPROM that might
not have been so bad, but now that it is usually in FLASH, 
maybe it isn't quite as firm.

DSP programming is different from FPGA programming.

(I keep forgetting if the group is named for digital signal
processing or digital signal processors. Since it is in comp. it
seems to me it should be the latter.)

-- glen