What Does 75 Meters Look Like?

[Pete, WA2CWA]

Larry or Art or anybody:
Are there any lap top sound cards that work well with the SDR? I poked around the Flex web site but all I could seem to find that are "approved" are cards that are PCI based.

[W8ER]

Pete,  they specifically say that there are no laptop sound cards that are approved. The ones that are approved, and the radio is only guaranteed to work with those cards, are PCI based with the exception of one of the Creative cards and that may be USB attached. If your laptop has a USB port, that might work.

Art may know more about this as he has an SDR1000. I am sitting on the fence and near buying one but my exposure is limited to reading the doc and working with Dave W9AD a small amount on his.



--Larry

[Steve - WB3HUZ]

What can I say? Eighteen isn't 20. :lol:  But actually I was commenting on the free SDR/demodulator software out there used in combo with a receiver/downconverter and a PC soundcard. You'll be lucky to get 18 kHz out of that setup since most receivers don't have IF bandwidths anywhere near 18 kHz.

You won't even get a 20 kHz view (instantaneous or otherwise) using the sound card and the SDR software.

Steve .. what am I seeing then on the SDR waterfall display? If you carefully look at the scale it looks as if the window is 10 khz either side of the center frequency. A little interpolation makes it appear that the scan may go out to 9 khz, either side, or a total of 18 khz. That's not far from a 20 khz view!


--Larry

[Art]

"I am grilling Dave on his and thinking very seriously about one. They appear to be pretty impressive, especially the receiver. Steve pointed out the 3rd order IMD product was measured at only 29 db down by the ARRL Lab and I didn't notice that earlier. That is certainly NOT impressive. I notice that there is a lot of experimentation going on now with different sound cards, ones with higher sample rates like the m-audio card. I do not know what sound card the ARRL used although I assume it was the Turtle Beach Santa Cruz.

How is yours doing? Have you been using it on AM?"

. . . and do continue to grill Dave . . . it is barbecue season . . .

There was quite a flap at FlexRadio about the IMD measurement. Gerald Y. generated a letter that indicated the settings and configurations were incorrect. He has been accurate in all dealings with me so my sense is this is accurate. It does illustrate the cutting edge nature of the rig though. If I had it to do again I would purchase the base (1W out) system and build my own PA/ATU. OTOH the PA and tuner are high quality units and integrated into the "box".
I have a minor problem with broadband noise on my carrier that is generated by the Santa Cruz sound card. A simple R-C filter is the solution and the implementation is due today. So, my use of the SDR-1000 on AM has been limited. Reports from the gang on 3825 are very good however. It helps that an EQ and spectral analysis software are included in the PowerSDR software. I can also select my TX bandwidth up to 20KHz. Typically I leave it at 4KHz. It's kind of like the 180MPH speedo . . . it's there if condx allow.
Slop bucket reports have been glowing.

The PowerSDR ap hangs every once in a while and power out control is not always consistent. That might be due to the fact that you can control every aspect of your TX signal and I am continuously diddling. . .

Some of the GUIs that are being worked now would knock your socks off. Kinda like the big bucks Icom GUI but you can move the panel elements where you want on the front of the radio.

There were concerns about the parallel port interface going the way of the 5-1/4 floppy. Now there is a USB interface.

Bottom line: I would recommend the low power unit as the best value. The RX is the best thing since sliced bread with stepped front end gain and brick walls where you want them. The TX is still in process IMO. However, the "static" concept of waiting until the bugs are worked out doesn't apply. The bugs are always being worked out and it is a new rig every time you update the software.

[Art]

Pete . . . there is a USB sound card that is being used so a lap top is a candidate. You need an amplified speaker so theres another box. I am considering a micro ITX footprint dedicated computer that has two PCI slots. My P4 3.0GHz runs at about 20% CPU utilization or so at full load of the PowerSDR software so choose your computer horsepower accordingly. Sound cards are always a major topic of conversation with "unsupported" cards parameters etc. The software is as close to managed open source as I have ever seen. More like an expanding project team than a user base.

-ap

[WA1GFZ]

You guys might want to put a bit more bias on the TX to lower the IP3
crud if the heat sink can handle it.  A sound card can't match HUZ man's
monitor device but who needs to see all that spectrum all the time.
The newer sound cards with higher sample rates will allow more viewing.
They will come down in price in time.

[W8ER]

Wow! Thanks Art for the information. It seems like everytime you run across an SDR1000 owner, you get a little different piece of the puzzle. Dave is real wrapped up in trying to find a card that will take the AES/EBU digital output of his Orban and still fit in with the SDR1000. He recently tried some other Creative card and I guess it really screwed things up for him. The "restore" function of XP got his registry back to the point he could recover and pop the old Santa Cruz card back in.

According to Dave they are trying to find a better sound card for the unit, one that will allow them to move the 11 khz IF up to some higher frequency. Since the sound card is the "heart" of the radio, that might be a good direction. I wouldn't be too concerned about the 11 khz IF for SSB use but on AM, well if my shorts were a little tighter and my voice had some 6 to 9 khz components, there might be some interesting products! Although I have heard Dave's and it's pretty darn good. When he decided to move his Mark V to the back shelf, well it got my attention!

and hey, with the AM Max fiasco  :lol: (at least I got one) , I should be leary of leading edge products but I guess I am not. I doubt that I'll wait much longer on this one.


GFZ -- They are working on the sound card thing rihgt now and yes, I think even if the bandwidth can't match HUZ's tool, that's why they call him "tripod", it still could be quite useful in analyzing the stuff that we like to look at.

--Larry

[Steve - WB3HUZ]

Take a look at WBBN, 1130 kHz

http://www.amwindow.org/misc/gif/1130kHzwbbn9apr050045z.gif

[Steve - WB3HUZ]

The pro-grade 96 ksamples/sec, 24-bit sound cards have been out for a while. With the proper SW these could provide on the order of 40 kHz analysis bandwidth. That's more than enough to look at someone's signal and see if it's FB or not. The trick is getting a receiver with that kind of IF bandwidth.

I guess you could scan/tune a receiver with a smaller IF bandwidth, taking an FFT at each step and then patch all the FFTs together for a composite look at the spectrum covered by the scan. With this set up you could cover as much bandwidth/range/spectrum and you wished, within the tuning limits of your receiver.

The trade-off with this approach is the amount of time required to cover the span of spectrum you wish to look at. This time is dependent on how fast the receiver can switch frequencies (settling time of synth, IF, etc.) and how fast the sound card/computer can calculate, store and display the FFT.

[WA1GFZ]

Many Mil RXs have wide band IF outputs. The cubic R3030 first IF is as wide as the preselector. Racal made a few RA6840s and DF RA6830s
with wide band outputs. WJ 8718 has one also. These receivers would be great front ends with a stage of conversion to base band or base band I/Q
to feed a sound card.
The FFT function works a lot better than a scan function for seeing things real time. The Racal MA2232 FFT spectrum monitor is cool but only 8 KHz wide.
The 96K sample sound cards will be cool when the price comes down.

[Steve - WB3HUZ]

Indeed. Although the price of the high end sound cards right now are far less than the price of the receivers you mentioned (unless you get a good deal or a fixer-upper).

The other thing to keep in mind is as you get wider IF bandwidths, the quality of the A/D becomes more important. Running a wideband A/D into most sound cards is a recipe for lots of spurious crap. The criticality of the sound card used in the Flex Radio bears this out, and this is narrowband usage.

[WA1GFZ]

Steve,
The Flex radio has very little filtering ahead of the sound card. RC filters after the first mixer and maybe some roll off in the op amps driving the sound card. A simple down converter on any receiver would work. I had good luck with a Motorola DSP eval module taking in a 15.5 KHz wide signal and the sample rate was only 44 KHz.  This simple down converter could also be used with SDR software as a demodulator.  My goal is a spectrum monitor and demodulation hanging off a good RX IF. The Cubic R3030 would work fine. I also have a RA6830 withan aux IF channel 15.5 KHz wide with it's own slow agc perfect to feed a I/Q down converter.
This down converter could be adapted to any 455 kHz IF. I used a modified Ft1000 detector board from Tom Vu as my base band demodulator but plan to build something better. The lash up was JS but the performance was very impressive.

[Steve - WB3HUZ]

Very interesting.

What did you need to do to get the FT-1000 board to work? I've heard it would unlock very easily or something similar. I have one somewhere in the pile of stuff, and if you thing it's worth messing with, I'll dig it out.

[WA1GFZ]

I made 2 modifications. I increased the cap in the loop filter then I changed the chip cap in series with the resonator to pull it up to 455 KHz.
I think the IF was 450 KHz in the ft1000. Pete SOV did the same thing but he used a trim cap on the resonator. The center frequency of the resonator is actually a multiple of 455 KHz. (X8 I think) The loop filter cap was 22 UF maybe 10 UF in parallel with the stock value. It still drops out
on a deep fade. Problem now is the capture time is slower. The Classic PLL
thing. I coupled the I/Q outputs with a couple film caps to the motorola DSP56303 EVM. I never tried it into a PC as the shack pakuter is too slow.
Pete provided the software and filter constants that took a little SW hacking but it worked very well. I had to add wait states in the software
to get it perfect but we never figured out why. The filter skirts were deeper than I wanted to increase the drive level to find the floor.
Skirts were about 100 Hz. wide for all bandwidths tested. (2,4,6,8,16 KHz)
The problem with the Eval module was I had to reload software every time I chanded bandwidthe and never worked out a good memory / control interface. The SDR guys made the sound card work so lost interest in the eval module.

[Steve - WB3HUZ]

Cool. TNX for the tips bro!

[WA1GFZ]

Give a man an EMI receiver and he will listen to tunes. Teach him how to use it and he will piss off managers.

[Pete, WA2CWA]

Pete,  they specifically say that there are no laptop sound cards that are approved. The ones that are approved, and the radio is only guaranteed to work with those cards, are PCI based with the exception of one of the Creative cards and that may be USB attached. If your laptop has a USB port, that might work.

Art may know more about this as he has an SDR1000. I am sitting on the fence and near buying one but my exposure is limited to reading the doc and working with Dave W9AD a small amount on his.

--Larry

Pete . . . there is a USB sound card that is being used so a lap top is a candidate. You need an amplified speaker so theres another box. I am considering a micro ITX footprint dedicated computer that has two PCI slots. My P4 3.0GHz runs at about 20% CPU utilization or so at full load of the PowerSDR software so choose your computer horsepower accordingly. Sound cards are always a major topic of conversation with "unsupported" cards parameters etc. The software is as close to managed open source as I have ever seen. More like an expanding project team than a user base.

-ap

Art & Larry:
Thanks for the info. Station laptop here is a P4 Gateway running 2 GHz, 256 MB memory, XP Pro, 2 USB ports, and on-board sound circuitry. I'll try a break away from my flea market spots at Dayton over those several days and go visit the Flex booth and see what the latest info is.

[W8ER]

Pete said:

Art & Larry:
Thanks for the info. Station laptop here is a P4 Gateway running 2 GHz, 256 MB memory, XP Pro, 2 USB ports, and on-board sound circuitry. I'll try a break away from my flea market spots at Dayton over those several days and go visit the Flex booth and see what the latest info is.

Pete ... Dave is using a very small Dell that he got off of Ebay, I think it was something like $125. It was one of those "just off of lease" machines. He has chosen to use a dedicated computer just for the SDR1000. It has a 933 mhz P4 and 256 meg of memory and is running XP.

Art really brough up a good point in planning one of these and that is Daves machine is seeing about 40% CPU utilization during use. That is doing just radio tasks!

After what I have seen Pete, I would not want to use the computer for anything other than the SDR1000, no matter how big and fast it was. I wonder about things like turning on the radio and then you get one of those Windows beeps or sounds and I wonder where it might go! Does it go to my speaker like normal or go out on the air?

--Larry

[Art]

"After what I have seen Pete, I would not want to use the computer for anything other than the SDR1000, no matter how big and fast it was. I wonder about things like turning on the radio and then you get one of those Windows beeps or sounds and I wonder where it might go! Does it go to my speaker like normal or go out on the air?"

You raise a good point Larry. I use my all purpose computer to control the SDR-1000. It's not that I don't have other computers. . . it's just that two computers won't fit on my desk. I like to multitask. That being said. I have had no problems with computer sounds going out over the air. The mic input is used for SDR-1000 TX.
I run word, project, thunderbird, firefox, and more background proggies than I should. . .  no problem. As I said tho . . P4 3GHz 1Gb 2sound cards, yada yada . . .
I am listening to 40m as this is being written. . . not much going on today. . .just a few slop bucketeers in the distance . . . 'must all be on their puters. . .
The RC filter cleaned up the wideband noise I mentioned yesterday. Now I can use the linyar. . . .


-ap

[W8ER]

Art.

I don't think you have to put them on the same desk .. the same floor, the same house even. If your computers are running XP, there's a piece of software Start/Programs/Accessories/Communication/ called "remote desktop cornection". It's real easy to set up and secure. On a 100 mb internal network there's practically no difference from being in front of the host (SDR1000)computer. It's not the slightest bit sluggish like PC Anywhere or VNC. On the remote computer, you can run it full screen, or windowed. You can connect to the internet, read your email or whatever and still run your radio. I did this with the RX-340 and tried it with the TS-870 .. it's flawless! Actually I ran the TS-870 from the hospital and Dave was able to control my 870 from Chicago too. You should try it.

So put your SDR1000 in the basement and get all of the radio gear out of the wifes gaze!  :badgrin:

--Larry