The AM Forum

I tried to use the HP8592L spectrum analyzer to look at the output of my signals and adjust the homebrew amplifier, but could not get a normal display on the thing, I did ssb with a 2 tone test, but got only one lobe on the display.
I also tried AM with one tone, same thing, it looks nothing like the pictures in books.
I tried every setting, and could see nothing that looks normal or useful.
I must be doing something wrong, but cant figure out what it is.

So I ordered the sdr-iq, that does have a very good spectrum display.
I also figure I can receive my own signals and record them in the software, and listen to them with various bandwidths set to get an idea of how to adjust the audio.
A different way to monitor your signal, by looking at the actual spectrum of your transmitted RF!

While the sdr-iq is a fair receiver, i think its great as a piece of test equipment...

Brett

What resolution bandwidth did you use on the HP.

Please report on the performance and your impressions of the sdr-iq after you have used it awhile...Curious minds want to know.......Thanks....Steve KL7OF

YES!  Some of this series didn't have narrow filters (RBW).  You need filters at least 1/3 the displayed modulation components -- forexample to see 1Kc, you would need to be able to set your RBW to at least 300 CPS - narrower the better.

The mfgr says  " Maximum display bandwidth of 196 KHz at an incredible 0.75 HZ RBW."

That should do the trick

But good luck on your purchase.  I'd be interested how this gadget works out

Al

8592L should work.  Scan width may have been too wide or BW too wide.
Maybe it is broken?? Sell it?

No, the spectrum analyzer is not broken, and its very useful when building things like VFO's where you can watch the levels and stability of the signal, even watch drift in Hz using the markers....
It may not go low enough in resolution to work, since it goes up to 21 Ghz...

I had an sdr-iq in the past but sold it to get something else.

It works very well, its the direct sample and downconvert type receiver, not like the flex system.
Its a great little box, powered by the usb port.
So a usb cable, an antenna and you are good to go from 500Hz (yes hertz) to 50Mhz I think.
The software was a bit clunky, no band buttons, band stacking registers, notch, but I think they are improving the software, and can make it do whatever they want in the future.
I think a new version is in the works, with lots more features.

One very interesting thing it can do is record the entire spectrum, from 500Hz to whatever, and you can play it back and tune around the bands just like it was live. No time limit other than what the hard drive can hold.

So I could record the entire heavy metal rally and listen to it whenever I want!

I plan on using it as a live monitor (spectrum) and to record my signal, then listen to it later adjusting filters to something like 6Kc and adjusting the audio till it sounds good....

As a receiver, its quite good, a little more background noise then the homebrew, the filters are very effective, and you can adjust them to whatever width you want.
Click tune on the spectrum display with the mouse, a VERY good detailed display of peoples bandwidth and modulation, its stunning.
Its smaller then a pack of smokes, and does not seem to need much of a computer to run fine, almost any computer with a usb port will likely work.

There are a few different programs that work with it, with more coming out I think.

I was going to wait for the flex 1500, but it might not be out for many months....


Brett


 

I looked, and the HP has 1KHz as the lowest resolution bandwidth....

I guess that is why I dont see the correct display.

Brett

The SDR-IQ is a pretty good RX.

I had one that came just as a bare board, before they sold them in a case.

You can record a maximum of 192khz chunk of band at a time.

(BTW  I  DID record the entire heavy metal rally on 75 meters.  250khz chunck of band from below 3700 to above 3900kc..  took just over 33Gb of disk space)


Good from about 3 kc up to 30Mc . max. ( the lower end was noisy, and unusable)


Brett has had one before, so he knows what he's getting...

For those who haven't it is a super step up from no SDR, or a softrock.

As far as performance vs price...  I think pretty good.
You'll spend twice as much to get a reciever better.

The review in this months QST is pretty good and its obviously built as a piece of test equipment and not as a SWL radio. 
I may also get one.

Carl
KM1H

I got an SDR-IQ back at the end of December (thanks Santa!) and have been enjoying it since then. It comes with it's own software, Spectravue, but there is an alternative software being developed by Simon, the same fellow who wrote Ham Radio Deluxe, called SDR-RADIO at sdr-radio.com. He's currently offering what he calls technology previews as he works up the software. I don't like the display on it as much as on Spectravue, it's slower and blockier, and I don't like the tuning method as much, but it does have band buttons and provisions for keyboard entry of frequency and such. He's just working on noise reduction routines today and will be adding features as he goes along. He seems to have developed a working relationship with the RFspace guys who make the SDR-IQ.

One very nice feature is that it also includes a separate server program that will drive the receiver and make the audio and control available over the internet. It automatically lists the receiver on a central server site that can be seen and selected off the regular sdr-radio console (select Input Source, then Remote Via network, a window will pop up - choose browse web and look for an open receiver. Be sure to click start after you make the connection and then off and then disconnect when you are done so you don't hang the server) Mine is currently plugged into an 80 meter loop and available for listening that way. I was just listening to Tim on the SBE with it from my desk at work.  ;D

As a receiver, I'm pretty impressed. I'm not sure it's quite as sensitive as some of my other receivers, but I seem to be able to hear everything that I can on the TS2000. It's very interesting to be able to see the spectrum and find signals with it. I was looking for some AM action last night and the window was dead, and scanning around with it I found an AM carrier down around 3705 - clicked on it and found K4KYV tuning and testing and fired up the TS2000 and had a nice chat with him. I probably would have missed him without the ability to scan the spectrum and see an AM signal pop up.

The sdr-radio software doesn't allow you to record the whole chunk of spectrum like spectravue does, but it does let you click on an mp3 recording button and record the demodulated signal to an mp3 file.

I'm enjoying the heck out of mine. Download the free sdr-radio software and you can enjoy it too!  :)

Yep -- you're right.  You can begin to see 3 KC SB components.  Anything lower than that begins to dissolve into the carrier or other SB components.

I used to accept / calibrate those beasties here at Raytheon.  We stopped buying that particular model because we needed better filters (RBW) -- like down to 1 CPS.

Where that unit will shine would be to check harmonics.  You can go into the zero span mode and dink around with the filters and video filtering and use it as an AM detector.  Even FM if you slope detect.  If I recall things right, there is a volume control and a little speaker in the thing.  The output linearity is pretty good and you can use it as a sort of power meter.

Al

You can also use Winrad with SDR-IQ and SDR-14.

I'd suggest giving that a try as well.

I didn't realize you could run winrad with it. I did give it a quick try and didn't get anywhere, I'll have to revisit it. Apparently you can also get powersdr to run with it by setting up spectravue to make an 11khz output and turn off the demodulation and then point powersdr at the 11khz stream. I haven't tried that yet but saw some directions for it.

I'm new to all this and just getting my feet wet but I'm having fun.

Got an sdr-1000 coming next week as the next step of the learning curve.

You need to install "support files" to run the SDR-IQ and SDR-14 with winrad...

They are Here:

http://www.winrad.org/bin/SDR14-IQ.zip

"A different way to monitor your signal, by looking at the actual spectrum of your transmitted RF!"


Yes, a very important point.  Monitoring our own signal at the 1500 watt RF  level is what it's all about. Watching our own transmit I.F. is meaningless cuz it's gonna be clean no matter how bad the power amplification system is ahead.  For example, I understand the Flex TX  spec is about -25db IMD, so this wud be a problem driving a big amp in a congested area like the DX window .

Question: Do the common Flex rigs look at the high level RF output or the I.F. on transmit - or do they even have an option to input this external (1500w) signal into the spec display?

BTW, I'm still digesting the SoftRock 6.2 info and will need to order a xtal.  Thanks for the info and help, Bruce and Frank.  I may look into your SDR-IQ idea, Bruce, before I proceed too far with this.


Oh, on your spec analyzer problem:  When you input the two-tone into the ssb rig, does the standard o'scope show a modulated sinewave-type RF envelope? Unless the two tones beat properly, you may get just a carrier. If good, then try inputting (splitter) a sig gen into the same spec analyzer and see if you can see the "bug" next to the ssb signal.  How does a standard AM signal look on the spec analyzer when a 1kc tone is injected into the rig?  These should shed some light.

T

I really like the SDR-IQ.  I'm using it with the companion IF-2000 board and SpectraVue software to monitor/control the FT-2000 transceiver.  However, Tom is right.  If I just use it to look at the IF of the FT-2000, I can't see what is really going on with my own signal.  If you use it in close proximity to your own rig, make sure you protect the input!  Use a couple of back to back diodes across the input to swamp out any excessive RF.  You can even make-up a more elaborate front-end protector with diodes and a series lamp.  Lots of guys on the SDR-IQ and FT-2000 bulletin board sites have reported wiping out the front end, if not protected.

73,  Jack, W9GT

On the first point - dunno where that -25 IMD spec came from but all the Flex's I see on the band have an amazing drop off at the transmitter AF bandedge setting and drop like white cliffs of Dover.  I've included a PDF of some screen shots I took a while ago.  The first page was a screen shot taken of a local station running a 5000a into a HB linear putting out legal limit.  You can only see the first 25 dB due to band noise which accumulated because I was on peak hold but I'll wager that without that noise that station's IMD would be quite acceptable.  This guy cannot be heard outside that window at all.

On the second question - no - the Flex only looks at what's going on inside the box and I'm not sure where it takes off the sig.  However, one could hook up to RX input from a coupler/sampler to a regular xmtr output and look at the products but the 5000 would have to remain in the RX mode to do that - I think.  Now that I think of it - I do have the second RX board installed - it does have its own RX input.  Anyone out there know if it could be used to monitor the output of a linear while transmitting -- that might be possible.    Might be an interesting experiment -- one that I intend to try some time.  It really is just like a S/A

Al

Spectraview, winrad, and there was another program that worked with the sdr-iq, but I forget what it was, and now the new sdr-radio.
Most of the stuff was sort of simple and crude compaired to power sdr, but that will likely change over time...

While I will likely use the sdr-iq as a receiver in the den, you can post here, get email, and listen on 3880 at the same time on a slow laptop, I think it will mostly be used as a TX monitor.

The flex 1500 might work a bit better as a receiver, maybe not, but its only got a 48KHz display, and it might not be avalable for 6 months....

Brett

I don't think any of the newer radios are better than about -30 or -32 dB IMD. This is almost 10 db worse than some of the better tube rigs of the past.

You cannot determine the IMD performance with on-air test with voice input. You can make relative comparisons but that's about it.

I plan on just using a little (3 inch) antenna on the sdr-iq in tx monitor mode, or maybe no antenna at all, I will just set the level adjusting the antenna size/location.

The flex looks at its TX signal past the power amp I think, but not what comes out of an amplifier.
The 2nd receiver might be able to do so.
They are also working on the receiver sampling the TX output and correcting imd and so on.
Maybe they will be able to include an amplifier in that?

Brett

The flex stuff has tone generator stuff built in, 2 tone, sweep, triangle, saw tooth, maybe square wave.
I was doing (trying to) the 2 tone test and looking at the spectrum analyzer, with the flex in ssb going through the amplifier.
If I set the two tones much wider, say 200Hz and 4000 Hz, would that work?
Is there some sort of formula for the frequencies of the two tones?
What would you do with a sawtooth or triangle waveform, look for the waveform on a scope, to see if it looks like a triangle or saw tooth?
It seems it would be hard to measure distortion that way, with 2 tones, you get the 2 tones, and anything else is distortion which you can see and measure the level of....

Brett

The triangle wave form would be an easy way to look at the envelop in the time domain and look for flattening.  Sort of like the trapezoid approach.  Triangle, sawtooth and square wave have their use in measuring amplifiers.  Not sure what use they would have in AM mod service except to show low freq response of transformer coupling or ringing to indicate strange stuff going on in the upper mod freqs.. By definition, it would be difficult to make meaningful measurements using these waveforms because freq response limitations of, say, 5 KC would remove much of the harmonic content needed to measure performance of an amp... Might be useful in checking the lows tho'.. (I'm repeating myself here)  But then, a good S/A would do the same thing -- the current topic of this thread.

When I got on with K4KYV last night, I disconnected the SDR-IQ but left it running. I could see some of my signal pop up on the display, but not a lot of it with just the empty connector. I think a couple of inches of antenna might work well enough for a monitor. I'll give that a try some night soon.

I am also planning to build up an input protection board. Got a couple of husky diodes and a teeny little lamp at RS to cob one together. I'm also going to have to come up with a more foolproof switching arrangement on the antennas so I don't have the SDR on one loop while I'm transmitting on the other. The feed points are only about 10 feet apart and the 75 meter loop is inside of the 160 meter loop. With the amp on I'm going to be putting substantial signal into the 'off band' antenna. I should plug the scope onto it and take a look just to see some evening.

Powersdr does look to have the most horsepower and features. I'll have to look into how that interfaces with the sdr-iq. I also need to figure out how much CPU and mobo I need for a dedicated flex computer.

With my QS1R, I short the antenna terminals on transmit, and have PLENTY of signal to monitor myself... and there is no "front-end" ( no filter, pre-amps etc).

You might consider a BNC plug, with a 50 ohm resistor across it, with a little piece of wire attached....

It's those pre-amps in the SDR-IQ you need to worry about.



Tom,
The IQ's pop up on the used market quite often.... though nice to get new....warrantee etc...

Of course, considerably more investment but WAY more useful than the softrock...

"On the first point - dunno where that -25 IMD spec came from but all the Flex's I see on the band have an amazing drop off at the transmitter AF bandedge setting and drop like white cliffs of Dover. "

Yes, all the Flex's I've heard were clean on the air too.  If you do a Google search for "IMD Flex" you will come across threads about this specific problem in the past, but maybe the new ones have been squared away.  

I would like to see someone do a scientific two-tone test on ssb to see what the real numbers are from the output of the final amplifier. The ARRL has, but I'd like to see an off-shelf test done by one of us with no axe to grind. I know that Chuck, who has a Flex 5000, said his was not as clean as his FT-1000D and planned to use the Flex just for RX and the 1000D for TX. This was about a month ago. (The 1000D specs are -32db for 200w and -36db IMD 3rd for 150w output, which is acceptable.)  I use my 1000D at 40w pep to drive a heavily loaded tube amp with low plate voltage that produces even better numbers than this. The result is about 250w output pep of super clean ssb or AM to use for whatever..

The chat here about putting a stub antenna on the input to sample TX RF is a big step and should begin a new trend towards monitoring our own signals "on the air."  That's the main reason I'm pursuing it myself.

When the HuzMan stopped by here last Oct with a hi-tech spectrum analyzer, it showed me my solid state IPA was poor. It also showed that Dr.Love was an exceptionally clean linear. I was able to build upon that information and improve things even more as a result..

There ARE sweet spots when adjusting all the many parameters of an amplifier chain to become extra-clean- that's what a spectrum analyzer will tell us through trial and error testing. It's well worth the extra effort to set up..

T

Short of starting a new thread Tom, try this.

I purchased a 40 DB iso "T" years ago for tapping into repeater antenna circuits to inject weak signals or monitoring. It was expensive and I couldn't resist finding out how it worked.

It was an SO239 "T" with something odd. The long  portion was normal but the branch or "T" line didn't have the spring clips that contact the center pin of the PL259. I found out the manufacturer simply disassembled the T and ground off the clips and a small amount of the stud that threads into the long rod. I assumed they calibrated it to 40 DB of isolation and reassembled it.

Since than I have made 5 or 6 of them. I use one in my QRO line for the frequency counter and another for the HP spectrum analyzer. Either instrument would fry with high power on them.

With 40 DB of isolation I suspect an SDR receiver would be very safe. If you need more isolation just grind more off. Don't forget a small dab of lock tight to keep the stud from backing out.

Mike

I am going to try a small antenna, right on the radio, since I wont be using it as the regular receiver.
When I had one, I left it hooked up in the den, and ran a cable to the station control, and even with full power going through the station control box did not blow up the sdr-iq.
The sdr-iq was not selected, but there is a lot of rf in the station control box...

Yes, I built the amplifier, like usual using no known design, so need to test things and see just how dirty or clean it is, and where the high voltage and drive levels need to be for the cleanest output.

I really don't run the flex into the amplifier very often, as its only good for about 175 to 200 watts out in AM, but I still want to know what is up with the amp...

It will also be interesting to see what happens when I jam into the neg cycle loading setup on the 3x4D32 rig, or overmodulate on the 2X813 rig, and just how wide the 32v3 splatters....
I can record it with the sdr-iq and study it!

Someone here said something about neg cycle loading being nasty with a floating screen setup, and I would like to do some experiments with running the screen voltage at a fixed point and leaning into the ncl and see what happens.

Brett

Has anyone tried out the SDR-14, and compared it to the SDR-IQ?  Is the -14 actually worth 2X the -IQ, per the price?

The cleanest exciter I have ever seen is the HPSDR Penny at third order -55 dB  on 20 meters. I'm told it is even better on 75.
When I was testing the ERB amps I used a pair of HP8640B generators into a combiner to measure IMD. I was able to get into the mid 30s but never had the bias set high enough. Even the old HP audio generators had harmonic levels of -26 dBc so it makes it very hard to check an amp with high audio harmonic outputs. This is why I used RF sources throwing harmonics well out of the test frequency range. I bet a quality sound card could generate a clean two tone signal. so be careful with your source and make sure you can measuer it before you test an amplifier.
I think the problem in the EB104 is the transformer design. Also the shunt choke is too small. I would think MRI amps need to have low IMD.
FLEX is stuck in the past with a DDS source which has close in spurs. This helps to generate IMD. My homebrew Softrock is pretty clean since it has a crystal oscillator through a divider.  The softrock properly connected to a receiver will only be limited by the receiver and the sound card it is connect to.
The dynamic range of the softrock can be shifted up by reducing the gain of the two opamps after the tayloe mxer.

None of this is really relevant to measuring IMD using the appropriate two-tone input.

I don't know if the sdr-14 is a better receiver, maybe its a little better, but it does a 30Mc panadaptor display.
Not sure why anyone would want that, that is a lot to look at on one screen!

Brett

Yes, the two-tone test gives a standardized measurement that can be used across different rigs and situations.

Until I set up a good SDR spectrum analyzer with two-tone test, I will continue using a receiver.  A receiver is a great spectrum analyzer! Once I had a good idea of how my linear amplifier system was performing after Steve's spec analyzer visit, I then used my FT-102's receiver as relative guide to improvements. I used the nastiest sounding word I could find that generates crud up the band. Believe it or not, an exaggerated  "Yallo" does the trick. Normal talking doesn't come close... The Tron knew what he was doing back then....;D

I put a 24" ant wire on the back of the FT-102 and rolled it up or pulled it out to give a standardized S9 +40 over with full power into the dummy load using the test transmitter.  Set the RX bandwidth to 2.8 khz LSB and tune UP the band (in LSB) while socking a Yallo into the TX on LSB ssb. After the normal audio bandwidth of 2.8khz, the audio will disappear and the crud level will start. I found a good signal should have less than S9 crud at 3.1khz away. I was able to get it down to less than S5 crud with some sweet spot adjustments like VERY heavy loading of the IPA, high final idle, heavy final loading, low output of the  driver, etc. These S meter levels are relative - yours will be different.  

Be sure the TX signal is not bypassing the antenna and getting into the RX - test this by disconecting the receiver antenna. There shud be little signal.   Once you get a feel for what a good signal should sound like using your clean barefoot exciter, then add the linear and see what it does. Be sure to renormalize the receiver to S9 +40 over by rolling up the antenna wire a little, etc. Your bandwidth results will vary based on the filters, etc, but learn what a clean signal sounds like and go from there.

Bottom line is until a good spec analyzer is available, a good receiver can do an excellent relative job for testing and improvements.

T

I downloaded the new spectraview software, and also the new sdr console.
Spectraview has improved since I last used it, with various sliders on the screen to adjust things, rather than opening menu's to get to things.
They still don't have drag and drop passband shift, and filter widths, maybe in the future...

Sdr console has band buttons, but is still in development, and lacks a few things.
Both do not include sync AM yet.

Makes you want to be a geek and learn how to make your own program to control these things....
Flex is working on new software, who knows when its going to be done, and how many bugs its going to have in it, but it should make a great radio much better....
There is a LOT of very neat stuff they could do if they got their butts in gear.

All these efforts seem to be mostly one man operations, done by people in their spare time.
Makes you wonder why the Japanese don't jump in and blow the one man shows away, or even Ten Tec....

Brett


 

Following the topic points relative to my QS1R.  My T/R relay's rcvr. terminal is also grounded on transmit; easy transmit signal monitoring.  I like the idea of a two inch or so stub antenna for monitoring all the shack's rigs.


Steve, you should have been a technical writer...  relevant, succint and to the point.  ;D
.. or are you?

I'm completely irrelevant. The point is, however, relevant.

Have had mine for about a year and I love it. I use it at home a lot and have found it very interesting to use compared to the regular panoramic display ion my Icom 756. I have found a lot of odd signals across the entire spectrum and see things I never hear- Some of the govt testing stuff I guess.
I use it in conjunction with "go to my pc" to log in on business trips and listen to what is going on back home. Depending on the speed of the local connection I sometimes have to back off the graphic intensive waterfall display.

Spent many nights listening to local 160 or 75 AM when cross country or out of country

Right now it si my favorite rcvr.

One thing of interest is that if I listen to the SDR-IQ and a regular rcvr there is a delay of maybe 1/2 a second in the audio from the SDR.

Carl

/KPD

I have been entertaining the idea of purchasing the SDR-IQ, now that I have a laptop that I can easily transport to the shack, but would probably use it more as a pan adaptor and a piece of test equipment than as the main station receiver.

It would be interesting to compare its AM reception to that of the 75A-4/Sherwood combination, and its selectivity to that of mechanical filters.  Bernie, W8RPW says he prefers to run his off the i.f. of his 75A-2 or HRO-60, than to use it as a stand-alone receiver.

If I were surprised and it really did out-perform all my present receivers, I would probably still want to add a passive stage of selectivity, something like a scaled down version of a wide range antenna tuner built with receiver grade components, between it and the antenna.  My Kenwood R-1000 picks up an incredible amount of images, heterodynes and buzzies on the longwave band, but adding a simple tuned circuit to the  front end pulled the European longwave broadcast signals right out of the background noise, even to entertainment quality at times.  Most present day solid state receivers have little or no front-end selectivity other than a series of broad bandpass filters that cover up to an octave of spectrum each.  It is bound to hamper reception when the active first stages of the wide-open receiver front end are being bombarded and pounded with strong signals over a swath of several megacycles each side of the station you are trying to tune in.

I recall some years ago a ham friend about 8 miles away bought an expensive solid state transceiver of the era that was supposed to have an excellent receiver section, but he was perplexed by the persistent fact that I could comfortably receive stations on my pre-WW2 HRO equipped with outboard mechanical filters, that he couldn't even hear on his ricebox.  He wasn't using a shabby antenna, either.

I can't speak for the SDR IQ thingie, but well implemented digital filters will outperform any analog filter. Even current day crystal filters are superior to the revered Collins mechanical filters.

K4KYV said
I suspect you're right that some front end preselection wouldn't hurt. And I also suspect that the phase noise would limit it's absolute performance compared to some receivers with analog VFO's. But good enough is the enemy of better and I find myself listening to it more and more because of it's convenience. I've been using it mostly remotely, even in the house as well as the office.  

Don, why don't you hit up sdr-radio.com and download the software and make a connection to my sdr-iq or some of the others around and give a listen compared to what you are hearing with your rigs. It won't be a direct comparison - different locations and antennas, but might shed some light on the issue. I'm not sure the sdr-radio software gets quite the performance out of the unit that the spectravue software does, but at least it's a start.

BTW - nice to chat with you the other night.

I cant say if you would find better performance out of the sdr-iq, its more a low end product, but it did seem quite good in my shack. Not as quiet as the homebrew, but I had no overload issues, no problems with super strong broadcast band signals, etc.

Get one just for the spectrum display, for doing tests, monitor uses, and the panadaptor.

The flex 5000 DOES seem to be better then almost everything else out there that I have tried, its also not quite as quiet as the homebrew, but has sync detection, passband tuning, the ability to see and move the filter around with a mouse, you can have ssb qrm and slide the filter over (on one side) just till it clears the qrm, and its gone!

I suspect the sdr-iq software will get much better over time...

Brett

Yes, Carl I have noticed the audio latency between the SDR-IQ and the transceiver.  I have to listen to one or the other.   But the delay is very noticeable in the SDR-IQ.  I don't know if this is a function of the receiver itself, or the software.  I don't know if there is any way to reduce the delay or not.

73,  Jack, W9GT

Unlikely.

There will always be latency when performing FFT filtering. This is because FFT filtering requires some number of samples to work. The sharper the filter, the longer the latency.

Analog filters have a similar effect, but their latency is small enough that it manifests itself as a phase shift.

Since digital filtering cannot be done on a per-sample basis, there will always be a delay until sufficient samples have been accumulated before there will be any output from the filter.

This is why I'm not big on the approach of digitizing the entire spectrum and using FFT to segregate the information you want from the information you don't. It's a tremendous waste of processing power, and doesn't address the issues that a selective RF section and IF filtering are intended to deal with (front-end overload and IMD, to name a few).

It will be some time before the technology is in place to allow flexible digital filtering with low latency, and zero latency in any digital system is physically impossible.

Even the bleeding-edge technology we use at work (a military SDR project) introduces a noticeable latency, with some of the best DSP talent in the field working on it. It's par for the course.

Still a darn handy tool for the shack, though.

--Thom
Killer Agony One Zipper Got Caught

Thanks Thom!  Well at least we know it is an "expected" phenomenon.  It can be annoying if you try to listen to both at once.  There's a little too much delay to call it an echo effect.  In practical use, however, if you turn off the audio from the SDR-IQ, you really don't notice the delay that much when looking at the spectrum display. 

As for the point about looking at the whole spectrum.  Isn't the SDR-IQ just looking at 190 KHz at a time?

73,  Jack, W9GT

You are correct.

I wasn't actually referring to the SDR-IQ with that comment, but some SDR packages do take that approach. "Because we can" is often equated to "best practice" when it really shouldn't be. There are some things that can be done in software that are still better left to hardware at this point in our technological evolution.

With today's technology, my preference would be analog RF and 1st IF, with a digital 2nd IF and AF for a complete transceiver, but that's just me. Proof-of-performance applications (such as what's being discussed here) and other bench roles are a better application of "software everything", if you don't mind the added latency of additional FFTs in the signal path.

Every good thing has a down side. All in all, latency is the only guaranteed drawback to any DSP-based system. The reward is usually well worth the sacrifice.

The only time the latency seems to be an issue, is while trying to monitor yourself..

Luckily with the QS1R the latency is so low, it gives the feeling of being in a large room....  (less than 50ms)  not quite an "echo".

That is, in part, because there is no soundcard in the system. (CAN be, but no need for it).

Still just enough to make it a little annoying.....

BINGO. I didn't even think of that. There's ALWAYS buffering at the soundcard. The more buffers your audio has to bucket-brigade its way through, the longer the propagation delay is going to be, and the more buffer management the processor has to deal with (which really hurts if the same processor is also performing the DSP arithmetic).

Hardware definitely makes a difference.

The reason the latency is higher on the sdr-iq is because it uses the computer sound card.
The qs1r has its own built in d/a converter and latency is VERY low.
It costs $1000.00 though, and might be dropped if the designer decides to do something else, or gets a real job or something...
The persius uses the computer sound card, and latency is very high.
Its just behind the K3 as the 2nd  best receiver on the sherwood list.
Don's 75A4 is not on his list...


And the sdr-iq DOES sample and digitize the entire 500 Hz to 30 MHz, and sends the 190 KHz you want to the display.
At least, that is how I understood it.
Quote below....


The hardware samples the whole 0.0001-30 MHz band using a high performance, 14 bit analog to digital converter (ADC) running at 66.6 MHz.

What gets me is that the box is so small for all the stuff you can do with it, and on top of making a good piece of test equipment, its also a good receiver.
The interesting things you see, I had no idea what some of them were.

I think the display is better then the current flex software.
But things are only going to improve on this stuff as they work on the software.

I don't suppose it will be long before they have great radios, rx and tx using the direct digitizing like the sdr-iq, but much faster and cleaner.

Brett

A/D into DDC is a lot faster.
Tom,
The FT102 has a dynamic range of 85 db so S9 plus 30 is close to the level the rX starts generating internal IMD if the S meter is anything close to reality.
Any amplifier will generate IMD if you drive it hard enough.

That's right Thom.

Actually, if I use the soundcard with the QS1R...
After a few minutes, you can see/hear the delay.

I mean to say if you're watching the display.... the sound lags behind the display..
By, oh, I'd guess as much as 500ms after a while.

If I stop the RX, and restart it, the ssoundcard buffer clears, and the display and sound will be just about in sync for a while... and the process repeats..

But I use the DAC that is on-board the QS1R for headphones and there is very little latency. (set for 50ms... can go a little lower).

Designer of QSR1 has a job, You might want to check him out.... and he doesn't need a job.
Perseus is a similar design just one generation older and slower A/D. I think th esound card just drives a speaker.
Coming soon a 1/2 watt transceiver from HPSDR. This is the one to wait for. It will have the same performance as the HPSDR project but all on one 4 by 6 board.
The first two boards are in test.

Interesting observation, Frank.

Well, the FT-102 still has the S meter set generously, so I suspect it is really about 59 +25 when testing. I do see the improvements when making adjustments on the transmitter system, so at least it's working in a relative manner. Besides, when I measure crud it is usually below S9, so that's a good thing considering the RX's dynamic range.

T

I took off yesterday as the xyl was getting eye surgury and had some time to try the receiver tuned off to the side tests.
I had the flex into the amp, and got nothing it seems out past the high frequency passband.
Beyond that, I did not see anything on the scope, or get any reading on the s meter.

Its got to have some grunge, but the receiver did not seem to pick it up....


Brett

Did your receiver system have greater than 60 dB dynamic range?  The 5000 has a better than -55 dB spurious / harmonic radiation spec.  I guess I need to understand what you meant by "...high frequency passband..."

If you drop the power by say 10 dB (as monitored on your power meter) does the indicated carrier drop by that amount on your receiver display indicating that there are no compression issues?  One would think that the linear would generate some additional grunge.  Or is that you have a really great system / amplifier?

Al

Brett,

In general:

Even a clean exciter will have some crud off to the sides, though way down.  Sock a nasty sounding "YAY" into the mic on LSB and you shud hear crud starting after 3kc up the band on LSB (using a ~2.5kc LSB RX), down -35db or so. It shud taper off into the RX noise floor at 5kc away, etc.  Add a linear amp and it will degrade by maybe 5db or so.  At least that's what I've found testing a number of exciters and amps.   I try to get the linear amp to add very little degradation to the exciter. The signal will never be cleaner than the worst component in the chain, of course.

A signal sounds like nice audio tones from zero beat to about + 2.5kc up the band or so  - whatever the bandpass of the TX and RX are.  The CRUD sounds like crackling up the band after that.

If you cannot hear the cracking, then you need to add more signal into the receiver until there is some crud up 5kc to hear on LSB. As Frank said, use the minimum signal to avoid IMD of overloading the RX dynamic range, but still enuff to hear your signal remnants up 5kc.  The remnants may be down -60db at 5kc, but are there, nevertheless.

I likely did not have enough gain in the receiver.
I was using the homebrew, with the pre selector mis tuned to lower the signal level into the mixer.
I had 4 divisions on the scope, about S9 on the meter, and tuning away from the signal, I only could see the high frequency stuff (sibilance), and after tuning past that (5Kc), saw nothing at all....

I doubt the amp is super clean, its four 813's!

The sdr-iq will arrive tomorrow, so I will use that for testing.
While I am at it, I should try and measure the dynamic range of the homebrew receivers.

How would I do that?

It seems to have VERY low noise, comparing weak signals on the 756ro 3 I had, the R390a I used to have, and the flex 5000, the homebrew always had readable signals the others could not copy becuase the signals were in the noise. The 5000 is very close, but i think the homebrew still wins.
I have never noticed any distortion even on the strongest signals.
The first stage is the mixer (running low voltage) which has agc on it...

Brett

Tom,
What are you using for a two tone generator? You want a stable input so you can actually measure the IMD level. I would use a step attenuator and put the RX into tightest filter position. If you know the two tones you will know where the imd is supposed to be. The nice thing about SDR is you will see the IMD real time with the two tones on a calibrated scale.

My mistake.  I tho't you already had your SDR Rx and was looking at a display.  I'm going to try the same thing -- I think I can do it with my second RX in the Flex going into the second Rx input with a sampler and an adjustable attenuator going so I can put the top of the Tx carrier where I want it.

At least that's what the Flex people say can be done

W1VD would be the guy for that question.

Al

Anyone have a simple and CLEAN two-tone generator circuit?  I need to build one.   

Frank, right now I'm using relative side-channel crud levels in the RX as I make improvements.  I already know the amp chain is clean - just want to make small improvements. But when I'm done, I will need to make some final measurements with a two-tone.

T

Try standard R/C phase shift oscillators.

I borrowed mine from Heath's Mod.monitor scope/sig.gen combo.
Dug it up to look at it.

Looks like I lifted just the twin audio osc. on a new chassis and added an outboard 115vac power supply.

 It uses a twin tetrode compactron though so, on second thought, probably not what you want, -unless you have a junker that you can take parts from..

There are two pots for setting each tone generator's strengths to match. The circuit is the ol' multi stage R/C phase shift, plate to grid osc. circuit and appears to be quite stable.  The detail of the phase shift couplet is shown.

Hello,
My SDR-14 is 4 or 5 years old  8) but after some attempts to update it, I finally realized that it can't able to replace a near-serious receiver :-X. As a low end spectrum analyzer it's dinamic range is a direct consequence of the poor selectivity of the preselector (lack of the AD conv) when it is connected to an a rod broad antenna, needs at least 10 or 20 dB of RF attenuation (10 dB externak to eventually burn replace) to turn off the oveload warning LED.
It is definitely a spectrum monitor with moderate receiving function uncomparable (to receive a single frequency) to an HRO or a lovely Super Pro  :P
It's very compact and I use it as a measuring receiver or as fast mouse click track ;) milair band monitor. Some rumors say that Italian Perseus is better but the audio delay.... :-\
'73 Marco
hnwe ;D

I wonder how the new sdr-ip is going to be, the spec's look stunning.
It should be for $3000.00, which seems way expensive for less then a fist full of chips...
80 mhz 16 bit adc, -170dbc phaze noise clock, 105 db dynamic range, 10 bandpass filters, etc

In using the regular antenna's, I never noticed the sdr-iq overloading, and I do have some very strong broadcast stations not to far away, but nothing like they have in Europe....

Still, its more a low end product, the next step up is at least twice the cost.

The sdr-14 may be worse then the sdr-iq in some respects, not sure how the 14 does the front end.

Brett

Tom said "Anyone have a simple and CLEAN two-tone generator circuit?  I need to build one."

I built one way back when.  I'll have to take it into work and check how clean it is.  If it looks good, I'll share the schematic.  It is fine for checking a SSB linear on a scope.  It's solid state

Al

Al I don't think a 12 volt final can do much better than -30 dB IMD3

SDR IQ sounds no better than a Perseus. HPSDR Mercury a bit newer has a 130 MHz A/D 16 bit so has a slight edge. $3K is a rip off. I would go with Perseus or QSR1. The HPSDR transceiver will also be 130 MHz. I think you can buy the 170 MHz A/D now.
It takes two clean signal generators, a power combiner and RMS volt meter to measure RX dynamic range. The procedure is in many handbooks including the ARRL solid state handbook. I use a pair of HP8640Bs a home brew combiner and a HP3400A. Minicircuits also sells them. The handbooks have designs for combiners or return loss bridges as they are called. A 1/2 inch core and 2 resistors. QEX ran an article on a good one a couple years ago. I remember I sent the editor a note on a way to improve the layout. He posted the letter a few issues later.
Tom, I thought there was a software program to generate two tone with a sound card. Check Alberto's site Weak signals. I think his will do it. Stu may have a source also. You need a stable clean source to really measure it accuratly.

"Tom, I thought there was a software program to generate two tone with a sound card. Check Alberto's site Weak signals. I think his will do it. Stu may have a source also. You need a stable clean source to really measure it accuratly. "

Yes, that would work, Frank.  Though I want to be independent of a computer if possible and build a simple SS box. The Belcher works FB as a stand-alone and I want to do the same with a two-tone.

I'll see how yours works out, Al.

T

I think it will be hard to build a pair of oscillators with harmonics down 50 db without distortion.

I got the sdr-iq today, and have it working in the background while I post here...
I tried the new spectraview software and sdr console.
Both have things about them I don't like, sdr console has a very nice spectrum display, but its very hard to figure out how to use it, its too small, etc....
Both don't have sync AM yet.

I still like the power sdr software best, but the sdr-iq does not run it.

Now to use it to make some tests on the transmitters....

Brett


 

Brett,

Try Winrad... it has syn AM...
I like it much better than PowerSdr...

I know, everyone likes something different   ;D

I will give it a try!
I ran some tests, it looks like the flex barefoot does about -35 db to the next lower lobe with the 2 tone test, and through the amp, about -32.
I did not see a big difference making various adjustments except for the plate voltage on the amp, below about 2000 volts, the imd goes way up quickly.....

Brett

Brett,

-35db IMD is a respectable number for the exciter. 

As for the amplifier, what happens when you continue to decrease C2 (load more heavily) until the power starts to drop way off?  Do you see some inprovement in IMD?   Is that the 813 amp in GG?  Interesting on the high plate voltage giving worse IMD. On my 3-500Z's, Eimac published a sheet that shows improved IMD when usiang a low 1500V. But's it's probably a different case with 813's in GG.  I run my 3-500Z's at 1500 V now, loaded heavily and get out about 250w pep, but real clean for whatever use.

T

I did not see a big difference when loading it or unloading it  past max output power, but need to study it some more.
As far as less imd with higher plate voltages, I suspect the bias set point has something to do with that.

Below about 2100 volts, I think the bias is to high.

I tried to get winrad working, but the bat file you run to get it to work....

Brett

ssb, 2 tone test, when I adjust the loading control, some intermod spikes go up, others go down, there might be a slight improvement in the highest spikes, a few db, while some lower spikes come up to the level of the next lowest spikes....

Power output and drive levels dont seem to have much impact if its not overdriven.

Overdriving the amp increases the imd 2 db.

I was on with the big rig (2x813) and it is wide.
The majority is under about 9Kc, but I have little artifacts out really far, like 20Kc.
The dual 31band EQ does not seem to cut them enough.

The flex seems to cut off right where you set it.

So I need to build some sort of cutoff filter for the audio chain.


Brett
 

Brett,

If rolling off the EQ sharply at say, 5kc and up still produces spikes out at 20kc, then adding a sharp low pass audio filter will not have much effect on these spikes.  The EQ will have rolled off big by the time it gets to 20kc.

Run some high level tones thru the system, bypassing the audio stages to see if there are audio parasitics being generated.  Think of other ways to isolate the reason for the 20kc spikes. ie, Are they RF generated spikes (RF in the audio) or audio generated spikes (audio parasitics in the audio stages)?

Well, if your 813 amp continues to stay at -32db IMD or better, that's FB -   it's never gonna have a spatter complaint, since most barefoot riceboxes are around that level today.

T

Brett,

You need to unzip the files into the winrad folder...

Next, run the batch file from that folder.

Then when you run winrad, it may ask if you want to use the file "ExtIO_SDR14"
Select it and click "open".

Then under "show options" tab...."select input"...  select SDR14/IQ

I did just that, and tried to run it as admin as well, all the files are in the winrad folder...
I need to play with it some more.

The looking wide was me overloading the RX, even though it was only reading 20 over S 9.
At S9, it looks normal.
The sdr-iq is not as good as some other sdr receivers when it comes to really strong signals...

No antenna at all makes it work well as a transmit spectrum monitor.

In a qso with HLR and a bunch of other people, Tim told me to open the eq out to 10Khz which seems crazy, but it did not look real wide on the sdr-iq...

Brett

Seems odd Brett...

It should just work   :D

============
BTW:
Check out the ebay link I posted...  There's  a WinRadio 313E  on ebay for $750.

(They go for $1300. new) Supposedly 5 months old.

What is that thing doing with a 70 Mhz IF and roofing filters???
Look in the spec's and that is what it says...

Looks like something old?

Not sure its much better then the sdr-iq!

Brett

Don't spend a lot of money on anything  but a Perseus or QSR1. There are a number of older modules around that are not worth it any more money than a softrock. Softrock trashed a number of overpriced modules.

I been following this thread intently. A few days ago I downloaded SDR-RADIO V1.0 so I could control some web based radio's, where there are many sdr-iq's all over the world listed. I get limited viewing times, but long enough to get a feel for the sdr-iq.

I even tried working my old high school buddy from Michigan on 75m. He could hear me fine, but I had trouble with him due to high receiving noise level at my QTH. As a last ditch, I got into an sdr-iq somewhere in New York, and we had a good FB contact that way. He copied me directly from Texas, and I copied him with an srd-iq in New York. The internet connected me to NY.

The contact got a little confusing since there was about a 1 second delay receiving the sdr-iq over the internet. I had to MUTE my laptop audio while I spoke, else I got confused with my own voice picked up in NY coming through delayed. That was VERY strange.

I was wondering if anyone has had experiences with the sdr-iq as a station receiver where you run your transmitter with the sdr-iq using PTT, and going back and forth? It seems that the latency delay of a second or so could present problems. Is the sdr-iq best as an auxiliary receiver, or can it be used as a primary receiver?

Jim
WD5JKO

Jim...

The latency you were experiencing was compounded by the internet link,,,'

Delay, on top of delay, on top of delay....

Typically there would only be less than 1/3 of a second latency, when the SDR is at your computer.
Depending on your soundcard and computer.

Latency like this is only a problem if you're trying to monitor your own signal... even then, it's just annoying....

I've been using the sdr-iq side by side with my TS-2000 and there is a bit of audio delay, but I'd class it as in the 300-400 ms range. About a syllable behind I think. I don't think it would be an operational issue.

BTW, which sdr-iq did you connect to? Mine has been on the air and available and is in danby, ny. I think it might be the only one in NY state. Was it mine?

With the sdr-iq localy, the delay will depend somewhat on the computer (laptops suck).
The audio outputs through the soundcard.

When I used an on line receiver in Florida to see if I could be heard down there (on ssb), there was about a 3 or 4 second delay! ( I was quite strong!)

The sdr-iq can be used as a station receiver, but its not the best, no sync detector, tuning is a little funky, there is no muting, you have to short the antenna input and audio output (no big deal), the delay is not an issue.
I have been spoiled by the flex, but the sdr-iq will likely do better than almost any vintage receiver, you can adjust the filters wherever you want, in 100 Hz steps, and the filter is very effective.
If you can get winrad to run, you can get a sync detector...


Software is likely to improve a lot over time.

You should have no problem running the sdr-iq, pulling mail, and surfing here at the same time on a slow laptop.
As with all sdr's, you can look at a wide bandwidth, and click on a signal to hear it.

If you have really strong signals close by, AM radio stations, maybe loran, it can overload the sdr-iq, and you might need a filter in the front end.

If you travel, its just the ticket, a laptop, the sdr-iq, and a spool of thin wire and you are good to go.

One very interesting thing I have been doing is monitoring myself, looking at my TX spectrum, and recording it for later study, and adjusting the filters to see what I sound like with different receive bandwidths.

One thing I have noticed is that I sound somewhat brain damaged in my speech, lots of ahhhhs, spaces where my brain is empty and nothing comes out of my mouth, thinking out loud, etc.

Brett

Francis,

   I have been into yours a few times, but the one I used that night was KA2GWR's. Yours sees to be busier, and I can only get into it once in a while.

   I don't recall which radio was which, but scanning band to band on some of these receivers, I'm pretty sure I have heard the same stations in the same QSO on two different bands, like 40m, and 80m. Then again, maybe I'm just confused.

Jim,
WD5JKO

Brett,

   All the info you just posted gives me a lot to think about. I want to have one of these to play with. That said, my hamshack (garage) computer is an old klunker. So for right now I will play with web based stuff that is free.

   The idea of having an sdr-iq at a remote location away from man made noise is interesting. Then a noiseless connection to a computer and the internet is another hurdle.

   Was also thinking of coupling it to the 2.something 1st IF of my Gonset G76 transceiver where I could sneak a mini ham station in the house...Yea right... :'(

Thanks,
Jim

Jim,
That is a very interesting idea, your own private remote RX in an undisclosed location.....

I get no noise from the computers, at least on 80 and 40 meters, it might be different on 10 meters....

I suspect if you have a computer with a usb port on it, it would work with the sdr-iq, although for really slow ones, you might have to stop some junk running in the background....

Brett

Considering the  QS1R see my copy of the developer's notes (Phil, N8VB) here.
Latency is on the order of a short audio echo. Good for fast break in on CW.

Yes, if you don't mind spending the coin, that is the one to get, if you like the software...
Not sure is other software runs on it...


Brett

Not cookbook yet except for Wincrash, but with some tweaking runs on Mac OS, Linnux, etc.  Also earlier versions run the Winrad  GUI, etc.  Phil has many Rev. C & D boards out there now.
Check into the Yahoo board if your interested.
http://groups.yahoo.com/group/qs1r/ (http://groups.yahoo.com/group/qs1r/)
 No real index so you have to use search function liberally.
Smug but still curious.  ;D

I did a lot of reading and research, starting with I/Q stream handling,  FPGA's, DAC's, you name it before I decided that it was for real and worth the money.
So we'll see.
I hope it remains viable for a couple of years, enough to get a complete neo classic receiver when looked back on a decade from now.
Kidding a little, of course; it's first class as it stands now.

Jeeze,  I still have my Sinclair ZX100, a whopping 16k ram, (with add on memory)
A kit before Timex bought them out.

GO COMMODE er Commodore -- I still have my SX64

Still have..

Mac 512
TI99A
Commodore 64
Radio Shack  TRS-80  (and CoCo II)

Last I knew, they all still work... 

Though I don't think any of them will run the 'IQ'     ;D

Oh, I don't know... the TI-99/4A* had that bus extension thang on the side. Might have gotten 8-bit audio out of it if the software was compiled onto a cartridge.  ;D

Somewhere I believe I still have a Tektronix computer with a BASIC interpreter in hardware, a phosphor screen, a built-in cartridge tape drive, and a GPIB interface. It was ancient when I got my hands on it 20+ years ago.

I only grabbed it because I had software that ran on Tektronix terminals, and this thing could act like one with the serial port extension I had. Always wanted to make a test bench controller out of it, but never did.

Now that would make a lousy SDR front-end!**

--Thom
Keep Around One Zero-Good Computer
*Yes, I had to Google it to get it right.
**Not that I'm trying to one-up anyone, here...

Yup your right Thom.... TI 99/4A 

Also have, but not working...  The  Timex/Sinclair 1000

What a workhorse   ::)   (it was pretty great, in it's time, for $99 )

I had a vic 20.
I got a microlog air 1 that plugged into the side for rtty and cw.
It worked well.

I got winrad running on the sdr-iq, I used an older version and it works (with a few error messages on startup).
Nice sync detector, no whoop like psdr has, and you can watch the passband move around to follow the signal.
That is different from other sync detectors where the inserted carrier follows the received carrier, but does not change the receive frequency. Winrad moves the passband around to center the incoming frequency.
I think I sort of like the version where the passband stays put, so you can tune off to one side and still use sync detection...

I DO like winrad though...lots of cool features, the drag and drop filters are real nice.

Brett

Brett,

I use winrad with my QS1R, mostly when I know I want to record a chunk of RF for later...

I like the SDRMAXXII for QS1R much better, but, untill later this year the recording function isn't in the QS1R software.

SDRMAXX does have a much better panadapter and waterfall display, than anything I've had so far...
It has much fater update rate, and higher resolution.... (and can see 50Mhz of band at a time, if you have a broad enough antenna)

the display isn't "blocky" or "choppy".  It looks and feels like a real-time spectrum scope.


Bells and whistles, whistles and bells.... I know....

But I also love the audio quality.. and the ease of fast tuning etc

Used one of those over 25 years ago to control receiver and spectrum ananlyzers. The screen was the same at the kind used in the Tek storage scopes. I remember writing BASIC stuff to draw stuff on the screen including cursive text and sinewave variations. What hoot.

Those toobs were the original flash memory: it took a bright flash to draw anything on them that wasn't already there.

Sorry. It's corny, but it true.

Actually ran a RTTY BBS with a COMMODE 128 (which I still have)  used the fancy 1571 drives - which I still have. Still have tons of SW for the COMMODE.   Memories :)

Yes. A big flash to refresh or erase the screen. The graphics were vector based unlike the bitmaps just about everything else used/uses. Cool stuff back in the day. Seems quaint now. The one I used was a 4052. There were a few others in the series.

Our college had one of those Tek terminals back in 1979.  It was *really* easy to draw graphics with that thing.  And yes I remember the screen erase flash...  Also,unique to the time compared to the other computer terminals around it had >80 char/line display as I recall.  And no screen flicker!

And very high resolution graphics - 1024 x 780 or 4096 x 4096 on the high end machine. Computers today don't match the 4096 spec.

It was also really easy to re-link said graphics apps to feed a plotter.

One of the Tek terminals we had at UMaine in the early 80's had a four-pen table-top plotter attached to it. Took its output directly from the Tek, though for the life of me I can't remember how. I usually re-linked the code and spooled the output to the big Calcomp plotter in the machine room.

Somewhere I still have code that made maps out of the BITNET and EARNET routing tables. It's probably somewhere in my giant collection of magtape reels I still hang on to.


I'd forgotten about that. It was greater than 80, but I don't think it was as wide as 128. I want to say it was something like 112 or so.


Hmmn... what was the pitch on the 4052? I think that's the same model I was using. 4096 sounds awfully dense for the images I remember conjuring.

Yes, I know... this has nothing to do with SDR.

The 4096 rez was only availble on the 4054.

We used a 4 pen HP plotter with these Tek machines. All that and a whiring tape drive! Lots of action.

I took the sdr-iq to work and loaded the winrad software on the work laptop, I have about 50 feet of wire in the trees, but the noise level at work is just nasty will all the telco equipment in the building.
40 was ok, but no AM activity, 80 was brutal with noise.
I need to get something better up away from the building.

Brett

One of our 'disaster recovery' provisions for the U was to set up a fairly capable ham station in our building.  ;D TS2000 with an HF-9 vertical on the roof. To my dismay, it's nearly deaf because of the noise radiated from this building or the others nearby. S7-S9 broadband crap! We had a horizontal antenna first and hoped that the vertical might be less susceptible, but that didn't turn out to be the case (and of course the radials are still horizontal on the roof). The saving grace is that if the power is out and the regular phones and network are down to the point where we need to depend on the radio - most of the hash should be gone!

I'd been trying to compare what I could hear here, and what I can hear at home on similar gear to get a feel for how bad the situation was. What an eye opener to bring in the sdr-iq and *see* the level of noise. About 20 db more noise floor than I have at home. I'm going to have to go through the place some day to see just what generates all the noise. We have gigabit ethernet in here to every room on UTP, and that's my guess for the source, but maybe there's something else I'm not considering.

Because of the noise, I've been running the sdr-iq on the remote server at home nearly continuously the last few weeks so I can tune in from the office in the afternoons. Makes a big difference in what I can hear. 

Hey Brett, what version of Winrad did you finally get to work on the sdr-iq and did you have to do anything special to make it run? (and where did you get the version you're using?). I'd like to give it a try on mine.
BTW - was nice to work you on 75 last weekend.

1.32, plus the files for the sdr-iq and sdr-14.

The building is full of sonet equipment, routers, etc.
The antenna is just a long wire  (not long enough) close to the building, and in the spring maybe I could put up a coax fed dipole somewhat away from the building.
Sometimes I have slow days and am hanging around (not often lately), and like to listen.

As it is, huge noise on 80, with a big hash at 3860, spikes all over the place, but 3885 was a bit clear.
40 meters was not bad, 20 meters was so/so, but signals were weak.

The roof is metal, and might be good for a vert ant, there is also a 250 foot tower, but its loaded with cell stuff, a repeater for the police, dead microwave stuff.

There are a number of big trees around though...

Last Saturday was great, large group, lots of interesting stuff was discussed...
I am still working on setting up the audio, and got a useful report from Tim, hlr..


Brett

 I am still having trouble with poor audio quality from my sdr-iq, listened to AM BC station last evening for about 30 minutes and that was all I could stand. it appears to have numerous low level echos that drive me nuts. also difficult copy on ham signals due to the same echos.  going to try some of the other software and see how that does. my sound card is a mid range card and when playing cds or dvds they sound fine. ( whatever that means) other aspects seem great, however this has become very disapointing to me.  I wanted to try SDR with possible intent of getting a Flex 5000, now not sure at all.  Bernie W8RPW

I had similar in a competing SDR product but traced it to incorrect settings in my sound card.
-Was with a Win SP, service pack 3 older Sony machine too that I don't use now.
It may not be the SDR IQ that's giving you the problem.

 

I don't think it would be a radio problem.
Mine sounds very good, I usualy use headphones as the sound from the laptop is very poor.

Brett