User Perspective: Paradigm Shift
By Lee Crocker,* W9OY
I recently was asked, “Is SDR ready for prime time?” Let me
answer that with some personal ham history.
Paradigm shift: I had two “big iron” boxes, Hallicrafters and
Hammarlund.
Paradigm shift: Japanese companies entered the
with a wide variety of simple transceivers. My big iron went the
way of the dodo. Transceivers made more sense—lighter, cheaper,
ever more features in ever smaller boxes.
The latest paradigm shift, full SDR, has already occurred. SDR
is of the present; the others, in my view, have become of the past.
SDR is cheaper to build and more feature-packed. Old-time radios
are basically etched in stone. Change is at the margins (add a filter
or two), not much more. The SDR can be changed radically in
form and function simply by changing the computer code. The
SDR can be perfectly customized to your station’s need, be it
ragchewing, DXing, contesting, etc. Upgrading involves a download,
not a soldering iron; entire radio fleets can be upgraded by
simple download.
Another paradigm shift: open source licensing. While others
use proprietary code, FlexRadio freely promotes experimentation
within the code among hams. Multiple branches of individually
developed code reside on the Flex servers for download. As good
ideas come to fruition they are readily included into the main trunk
of the SDR code, giving each owner a better radio experience. A
hundred enthusiasts’ brains are far more creative than one factory
engineer making all the decisions. It’s a critical mass of hobbyist
brain power, super-charging the future of our hobby.
Freedom and flexibility: We are almost at the point of “if you
can think it, you can do it.” These paradigm shifts are not “future.”
The results sit on my desk today, with performance that is as good
as or better than anything else the market offers. Today,
my desk holds only SDRs, radios that are not “of the future.” The
paradigm shift has already occurred.
The Paradigm shift HAS happened in spades!!! In this mornings email I received a note from Rich WB2JBS regarding this web site:
http://www.websdr.org/
If you go into the first site you are greeted with this
This is a partial display of an 8 band SDR available over the internet that is usable by multiple users. This picture displays 40M 30M 20M and 17M as well as the control panel. I always wanted to see what 40M SWBC looked like in Europe. If you look at the 40M band it looks like the sky is on fire. This is what 40M SWBC looks like in Europe. The sky is on fire with RF!! I placed the filter on the strongest station in the pass band. Just take a look at the S-meter! -26 dBm is a true 47dB over S-9. I never see this kind of signal on my Flex stuff even in the strongest contest situation. The strongest stations on my Flex radios are in the -50 dBm range.
With this receiver you are able to see the activity on 8 bands, and all users can see that activity. Recall that the output of the SDR is some bandwidth like 96khz. The hardware acts like a data engine. It sucks in a slice of the RF spectrum (like 96khz) and spits out that 96 khz as data. This radio on the other hand is a data engine on steroids!! It uses a very fast A/D converter that sucks in the entire shortwave band up through 18mhz. The A/D then spits out the data as a 18mhz digital base band. This raw 18mhz digital base band is further displayed, processed, filtered and demodulated in a FPGA.
In fact within this bandwidth you can place dozens of individual "filter/demodulator" (what Flex calls a "watch receiver"), and this is how this radio works. When you sign in, a watch receiver is assigned to your IP address. It is that watch receiver that you can slide around the various bands. Moving the filter, by left clicking on the black of the band of interest moves your freq up and down the band. You also can grab the filter and slide that up and down the band by left clicking and holding. If you put the cursor in the waterfall of the band of interest you can zoom in and out by using the wheel on the mouse. Once you do the zoom you can move up and down in the band by click and grab within the waterfall, and move the freq of the water fall up and down. Once you have a station tuned in you can adjust the bandwidth of the filter, each side independently. By judiciously adjusting you can center the filter according to the CW offset to which you like to listen. You can also grab focus on the filter and tune by moving that up and down. Your watch receiver is represented by a little icon that looks like a filter. To change bands you simply click the new band. Its very intuitive and ergonomic. PowerSDR also allows for dozens of receivers but the problem is there is no easy way to allow all that data coming from many receivers to be interpreted. After about 2 receivers the brain starts flashing OVERLOAD OVERLOAD. This of course is the solution. If you have many receivers sucking in tons of data, you need many ham operator brains to understand the data!! PA3FWM's program will allow receiver numbers of 100 or more!
There is also a display that shows who is using the "radio" along with you. Below is a partial display:
If you put your callsign in the box at the top where your watch receiver will be displayed with your call sign, and it will show what band and where in the band you are listening. If you don't supply the call you will be displayed by your IP address. If you look in the 40M box you will find my call sign. On the 8 bands there is a total of 68 watch receivers aka users in the entire bandwidth of the digital base band
How cool is this? The software was written by PA3FWM and the "radio" resides at the University of Twente in the Netherlands. This thing is cooler than a box of softrocks. If you go to his webpage you can see for yourself the hardware associated with the signals to which you are listening.
How would you like to know what your signal looks like in the Netherlands? Set up a few of these around the country and you will always have a different take on propagation. Imagine being in a contest where you could just change the position of your receiver across the face of the earth. Oh I bet those grumpy old contesters that hate anything new are peeing into their boot right now at the prospect!!! I can hear 'em now crowing ROOFING FILTER ROOFING FILTER BEAM BEAM (If you crow this in a small group it will sounds like the angry crowd chasing after Frankenstein) That mental picture is kind of the picture I get when the contesters get a load of this!!!
This is a picture of the hardware!!! Look at how simple this looks. It points out once again that the money shot for this kind of radio IS IN THE SOFTWARE
Just remember if you get fired for listening to the radio from your desk all day long it isn't MY FAULT
Check this out soon as the 8 band version is going off line in a few days and will be replaced by a 3 band version that uses 3 RX's with 48khz bandwidth
Beam me up Scotty this sucker ROCKS
73
