SDR-1000 on the air

[Art]

'just put a new rig on the air. It's a FlexRadio SDR-1000. It's software defined and really works nicely on AM rx ('haven't figured out how to tx on AM yet). The bandwidth is variable from 25 Hz to 9999 Hz so all the AM gangstas sound great. The integrated pan adaptor display really shows what is going on.

-ap

[WA1GFZ]

ap,
I have been looking into the SDR again and found some real specs.
It looks like it has evolved into a cool project. I bet the next version of hardware will really perform. A also think this approach with a big linear
is easier than all other methods including class E.
It was always a very cool project but I wasn't going to get into it until I saw real numbers.
Imagine a unit with 300 watts P-P and a newer mixer with plus 40 IP3.
fc

[Art]

oh yeah, it was awsome during the vhf contest. 'had strong corntesters and was able to pull out the pw sigs nicely. . . . it beats out the TS-2000 for strong signal handling.

on am the synchronous detector is a real plus too. . . .

fun stuff but still a little rough . . .

-ap

[flintstone mop]

Hello
I am also tempted to 'borrow' from our pile here at work one of those Motorola ALE type 100W HF radios. It's all software but totally programmable. I bet it might have real nice AM audio. I'll keep you all posted. It is a clumbsy radio to try to use with out being hooked to a computer to get into the 'soft controls'
G'day  ' 73  Fred

[Pete, WA2CWA]

Frank: Did you review the specs and lots of other info in their manual?

http://www.flex-radio.com/Assembled_SDR-1000_Manual.pdf

Art said - fun stuff but still a little rough . . .

Art, what do you mean by this? Some additional details would be helpful.

[Art]

Hi,
The 'little rough' part is mostly due to the radio being a brand new product:
1. The manual is version 0.4 and needs quite a bit of work.
2. AM, SAM, and FMN TX don't work yet.
3. Interconnection and set up are not as intuitive as you might expect.

On the other hand:
1. The receiver is outstanding. better than FT-1000 and TS-2000 in sensitivity and features for RX tweaking.
2. AM, SynchAM, and FM work great on RX
3. The band scope is outstanding and one of 7 possible displays
4. SSB audio quality TX reports are glowing. 'might be due to the integral9 band eq.  
5. Moving and varying the passband from 50 Hz to 6 KHz is smooth and solid
6. It outperforms the TS-2000 in weak signal work, particularly in the presence of other strong signals. (eg corntests)

I am working with the software developers at Flexradio to get the large and small kinks worked out.

A little rough but worth it. I am listening to 80M while typing this on the same puter. . . .

-ap

[WA1GFZ]

AP,
I wonder if they have considered a USB or 1394 interface???
I suspect this will be quite a radio in time.   fc

[Art]

The optional tuning dial uses the USB port. It was kind of funny. They advertised the tuning knob as a USB tuning knob. For about 1/2 hour I struggled with the question of why it would only work on upper side band. . . . DOH ..  . .

The SDR uses a parallel port and three cables to the sound card as a baseline  connection to the computer.

-ap

[WA1GFZ]

AP,
I just wonder if the parallel port will go away in time. New printers use the USB interface. I would think the parallel port could be an EMI issue if one used a poor cable.
keep us posted, this will make the rice box builders fear good old US
made goods.
Imagine this on a VME or VXI bus without bill gates overhead.
Or a dedicated processor that could take software down loads from a PC.
This is one of the coolest projects I've seen since Heath kits.
fc

[w3jn]

WHile this looks like a FB box in all respects, I saw with horror that it will only work with certain sound cards.  I've discovered the hard way the pitfalls of using computers as instrumentation controllers.

1)  Anything with a proprietary bus card, no matter how enticing, should be avoided at all costs.  When that card craps out (and it will!), the manufacturer won't be able to repair and/or cannot/will not obtain parts.  The whole system is thus rendered useless.

2)  Anything using trailing edge technology (such as parallel busses!) should be avoided.  The time will fast approach when you will not be able to buy a computer with such equipment.  When the computer craps out and you can't buy a replacement, the whole system is rendered useless.

3)  The computer industry advances what seems to be 10X the rate of the rest of the electronics industry.  It's hard for a small mom-and-pop manufacturer to keep on top of all of the changes in the computer industry and be able to update their software to run on the latest and greatest hardware and/or operating system.  Sooner or later, the instrument will no longer run with the updated computer (thus rendering the whole system useless - see a theme here?).

This isn't as big a problem for us cheapass hams that can scrounge used computers at hogfests, but I can state from sad professional experience that otherwise perfectly usable instruments are relegated to the dumpster for lack of compatible computer controller hardware/software.

I suspect that the lifespan of this sort of equipment is to be measured in single digit years, instead of multiple decades as is the case with tube gear (or any other equipment made before the wonders of microprocessor control).  As an example, I agreed to repair a bunch of Transworld HF transceivers for a friend.  They were all (except one radio) missing a pair of 2716 eproms holding the instructions for the 8088 microcontroller.  I had a devil of a time finding 2716s - and finally scored some used ones on eBay.  Then I had to search ansd scrounge for a eprom burner that would even take 2716s!  Many of the new ones do not.

This is not to denigrate this radio in any respect.  Rather, it's to provide food for thought when contemplating the purchase of hardware that is externally controlled by a computer.

73 John

[WA1GFZ]

John,
This is also my concern. USB and 1394 would be a better choice.
Performance will go up with new machines and you would be stuck
with an old interface. Heck I heard PCI Bus is going away.
You think 2716 are hard to come by try 2732s. I scored a life time supply
for the Racals. BTW 2816 would drop right in if you could have found them, EEPROM.
Still SDR is very cool and love to hear any news from users.  fc

[Pete, WA2CWA]

Geez, 2716's and 2732's. I had plastic bags of these things (I think 10 per bag) that I had in my $1.00 box last year at Timonium and several other hamfests before I finally got rid of them. I think the last bag I had ripped, so I just stomped on it, and threw it in the trash.

[w3jn]

Where was ya when I needed ya, Pete?

I have plenty of 2732s, and I *thought* I had a stash of 2716s also.  Of course the hamfests came up dry when I was looking for them, too.  

I recently scored a big box of crap with about 50 2708s, so if anyone needs any....

73 John

[WA1GFZ]

John,
I would be interested in 27C32s if you have some. Cubic uses 27C64s
and 27C128s. I have a couple versions of 3030 software if you ever need a copy.  fc

[w3jn]

I'll look but I think they're all straight 2732s.

[Steve - WB3HUZ]

Any 50C5s?

[w3jn]

If they were up your a** you'd know where they were!!!

[WA1GFZ]

Tom Vu controls the 50c5 market but the brown ones belong to Tim'sfriend.

[Art]

In the next edition of as the SDR turns. . . .

I was experiencing AM broadcast overload ('bout 20mV of B'cast RF here) and discussed it with the folks at FlexRadio. They are going to replace the low pass filter with a band pass to get rid of the BCB overload.
While removing the band pass board I couldn't help but notice the boards and workmanship are all first rate.
Also, I mentioned my concerns about the many opportunities for improvement with the owner and he said the SDR is always evolving. Undoubtedly they would go to another PC port in the future and the particular sound card (Santa Cruz) was chosen because it was one which had a high enough sampling rate to do the job. He mentioned most newer cards would do the trick but not all had been tested. (SBs have been tested.)
The innards are modular so boards can be updated as required. However, there was a lot of surface mount components. 'will need a bigger magnifying glass. . . .

-ap

[WA1GFZ]

ap,
You need a microscope. Cubic Mackay and others have made a nice small preselectors that are called pre/post filters. They also have a TR relay in them. This is tuned with a typical bandwidth of 10%. I have seen them
with thumb wheel switches and remote control. I think each decade is
4 BCD bits. This would make a great front end for the SDR and a smart guy could hook it to the computer to tune with the hardware. They mount
in a 19 inch rach 2U I think. I think they tune 1.6 to 30 MHz.
Your over load problem is my main concern with the present configuration.
Thanks for investing and reporting this.

[Art]

An updated software load was released yesterday so as soon as the BPF gets back from TX I will advise on the AM TX.

-ap

[Art]

OK, here's a cutting edge manufacturer that wants to make a radio for AMers. I responded with a first pass vs the capabilities of the SDR that I observed. Any additions would be appreciated.

"The specifications I cited are not in a specific document. They are from experience on AM and working with AMers.

'a more detailed TRD:

You already have the receive pretty well nailed but can improve receive features like an auto hetrodyne notch (ANF seems to be inconsistent but that is probably due to my operating inexperience with the SDR), and improving the straight AM detection (it gets a bit distorted on intermediate to weak signals).

I thought the power level control would change the carrier level on AM tx but haven't been able to confirm that because I couldn't get AM TX working. I will be hardware limited for a while due to me BPF being modified so won't be able to expand upon this until that is done.

The 150% + modulation and negative peak limiting will be a real plus. Near 100% modulation and audio restriction is a classic sign of utilizing a rice box on AM which is generally not viewed as desireable. [I use a TS-2000 but have modified the code to allow greater audio bandwidth and adjust the carrier vs alc to allow > 100% modulation.]

Audio bandwidth beyond 3500 would be good as well. 5-10KHz is not out of order on 10M AM. It would be inappropriate on 75M Sat night but so is wideband SSB. . . an operator function like the top speed of a Ferrari.

I will bounce this off of my AM cohorts if you want more detail. . . . "

-ap

[WA1GFZ]

AP,
Does the DDS have an internal modulator or is this external to the source.
I agree there should be a EQ screen that allows the user to select AM
bandwidth and modulation positive and negative peak. The internal software could set the output power to support the required modulation
or the user could be able to adjust the carrier power. I don't know if there is a loop around the final Output Power / VSWR. You could try this without the BPF if you throw an antenna tuner in for harmonic attenuation.
These guys are not AMers so may need some direction here. fc

[Art]

OK guys I need help. I am trying to convey the concept of > 100% modulation and have penned the following post. . . .

"I agree Bob. 150% positive and negative modulation is overmodulation and splatter will result.

Conventional (high level) AM PEP modulation would be limited to 4*carrier for 100% modulation. If you overdrive the conventional AM transmitter the negative peaks will generally cause minor splatter (Po is low at this point) but amplified would be a real problem. The positive peaks would cause splatter because they would exceed the power supply and modulator capability to reproduce a clean positive peak. . . .clipping . . .amplifiy that and you have a big problem.

However, if we limit the negative to avoid complete carrier cut off we have less than 100% negative modulation. The secret to the 150% positive is head room in the final PA. For instance; a DX-60 with negative peak limiting will exhibit no splatter due to carrier cut off because the carrier is not allowed to be cut off. The positive peaks though are allowed to exceed 100% by design and do not cut off in the positive because the final amplifier has sufficient capacity to handle the full PEP of the 150% positive peaks. A DX-60 might have 10W carrier and 75W PEP as a typical operating situation."

The programmer is having problems getting past the > 100%modulation = splatter and distortion concept.

Perhaps someone could convey the concept in a more articulate manner?

-ap

[Steve - WB3HUZ]

Just think of greater than 100% positive peak modulation as DSB with reduced carrier. You could also point them to some of the very good old QST articles found on the ARRL AM Technical Information Site.

www.arrl.org/tis/info/am.html