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12 bucks and a handful of parts or Building and using the Soft Rock lite




 
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Author Topic: 12 bucks and a handful of parts or Building and using the Soft Rock lite  (Read 80082 times)
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ka3zlr
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« Reply #50 on: February 17, 2008, 08:10:59 AM »

WOW...way cool...
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K9ACT
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« Reply #51 on: February 17, 2008, 09:17:10 AM »

Jack.

No you didn't miss the point and I started this thread yesterday morning.

The answer to your question is yes. All you need to do is figure our what the IF frequency is where you want to pull off the receiver and then email Tony.



The reason I missed the point was that I stopped reading when it didn't seem to relate to my needs.

I just ordered the IF version from Tony.

I am looking forward to this as I already brought out the IF node to feed to a scope but lost interest in just looking at the RF envelope.

This is really what I want to do.  As $12 Flex.

js



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WBear2GCR
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« Reply #52 on: February 17, 2008, 10:29:03 AM »


There seems to be somthing amiss with the suggestion to just buy the thing and plug it in - doesn't that reduce us to the dreaded appliance operator status?

Other than spending the time to read endless (and reasonably large) files on the Yahoo site, or having got started with the whole thing early on, is there no overview or FAQ for this board/kit??

Some kind soul from the Yahoo group sent me a block diagram... that's a start, but still doesn't tell me very much at all.

Ah well...

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KF1Z
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Are FETs supposed to glow like that?


« Reply #53 on: February 17, 2008, 10:54:40 AM »

Just what is it you haven't found yet Bear?

What part of the system do you want to know about?

The unit itself is very simple.....

It contains an oscillator, mixer, quadrature sampling ic.... that's it...

The rundown is:
RF in... (from antenna, or IF stage)...mixes with the LO...(down to audio frequencies) and the quadrature sampling IC , the I/Q signals generated   (2 sigs, 90 degrees out of phase)  go into the soundcard which on the input is used as the A/D converter...

From there, it's all in the software, and I can't explain what exactly is happening there.......

Hope that helps a tad....

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« Reply #54 on: February 17, 2008, 11:07:06 AM »

Bear,

You have to build it. Not appliance operation if that is your concern, other than that I can't figure out what your looking for. Magic Bullet? Holy Grail? Maybe you could just get one and figure it out for yourself!!

Get it -- build it and learn
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G - The INR

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« Reply #55 on: February 17, 2008, 11:16:49 AM »




Other than spending the time to read endless (and reasonably large) files on the Yahoo site, or having got started with the whole thing early on, is there no overview or FAQ for this board/kit??

Some kind soul from the Yahoo group sent me a block diagram... that's a start, but still doesn't tell me very much at all.

Ah well...

              _-_-bear

Bear, I'm squarely with you on this one.  I looked at some of those frigging yahoo group messages and they all presuppose that you know all this stuff to begin with, and it's bogged down with all kinds of minutiae which isn't useful to an outside who just wants a quick overview.  All I wanted was a pic, a schematic, and soundcard requirements.

This link is by far the best, but it appears the item described is NOT the same thing that everyone is discussing here.
http://www.amqrp.org/kits/softrock40/

That's the problem with projects like this.... the people involved all kinda know what was happening from the git-go but it's very difficult for someone who's just diving in to *quickly* make heads or tails of what the hell is going on. 

This isn't difficult stuff... it's just a LO, a quadrature divider, and a I/Q detector with a bit of amplification and filtering.  I see it connects to the audio input of the sound card; it was my impression from the first that it used the USB bus somehow (it does, but ONLY for power).

Reminds my of my college nuclear physics instructor, who, when skipping over some intermediate process too complex to describe, would say "...and a magic wand is waved, and we have..."  Grin
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KF1Z
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Are FETs supposed to glow like that?


« Reply #56 on: February 17, 2008, 11:27:06 AM »

""..
Reminds my of my college nuclear physics instructor, who, when skipping over some intermediate process too complex to describe, would say "...and a magic wand is waved, and we have..."  "



Exacly as explained here.....

http://www.greenmountainradio.com/files/science.jpg
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WA1GFZ
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« Reply #57 on: February 17, 2008, 12:33:12 PM »

Gary,
What is your crystal frequency. I run a color burst crystal that allows me to do a 15 KHz bandwidth. Your carrier looks to be only about 5 KHz away which will limit your bandwidth.
The height of the carrier tells me the audio level into the sound card is kind of high so it might be better to set the level controls lower and change the input attenuator to less attenuation. My carrier comes up about 30 dB out of the noise floor. Yours is almost saturating the sound card. You may have to reduce the op amp gain of the softrock card by changing 2 resistor values. I think Tony runs gain of 50 if I remember. I find in IF monitor applications gain of 10 is plenty.
Also, I wonder if you could get a stronger signal into the radio. It has to be a crystal oscillator though. I would like to see the phase noise performance of the 390 when the signal gets up to the point of just about saturating the sound card. I would like to see the strongest signal you can pump through without raising the noise floor. Maybe you could get the reference out of another radio or piece of test equipment. I think the 390 could serve as a bench mark for low phase noise and it would be a cool hunk of information for me.
After a while you will be able to tell the clean signals from the dirty ones by the width of the Christmas tree.
TNX gfz
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K9ACT
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« Reply #58 on: February 17, 2008, 01:32:51 PM »


There seems to be something amiss with the suggestion to just buy the thing and plug it in - doesn't that reduce us to the dreaded appliance operator status?

Great segue to another topic.... is the guy who buys a restored or working Valliant any more buzzardly than the guy who buys a rice box?  I don't think so.

>Other than spending the time to read endless (and reasonably large) files on the Yahoo site, or having got started with the whole thing early on, is there no overview or FAQ for this board/kit??

I think the answer is yes but no one knows where to find it. 

>Some kind soul from the Yahoo group sent me a block diagram... that's a start, but still doesn't tell me very much at all.

I have schematics but they don't help much either.

My credentials consist of having built one of the transeivers which doesn't work but I will still suggest that you send Tony $12 and have a go at it.  I just did and presume it will be like falling off a log compared to the tranceiver.

I have no idea how he can even break even at the prices he charges nor where he finds time to answer all the questions but if you have a Paypal account, your project will be in the mail tomorrow.

Tony Parks.....  raparks@ctcisp.com

In case it's not obvious by this time, you don't just plug it, you have to convert a bag full of parts and a circuit board into a useful device.  Tips on doing this are included in the info you can download.  Just don't ask me where I downloaded them from but I think there are links in the kit.

Have at it!

js



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« Reply #59 on: February 17, 2008, 01:51:16 PM »

Frank

The crystal supplied is 1.843 and I use the / x 4  jumper producing a 0.46000 center frequency.

Which resistors and what values to reduce the gain? Better yet could a pot be added to replace one of the resistors to have a variable gain control?

G
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G - The INR

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« Reply #60 on: February 17, 2008, 03:27:48 PM »

Gary,
The two feedback resistors go between the negative input and output of each op amp. I think they are R10 and R11 and presently 4.99K. These values need to be very close to each other or image rejection will suffer. Try hanging 1 K in parallel with each one. You can tack them in on the back of the board. The long leads of a pot would blow the noise floor. Then you will have to adjust the attenuator so more signal in coming into the module. If you are using a 2 resistor divider make sure the one going to ground is around 50 ohms. I noticed the carrier only 5 KHz away. This will limit your usable bandwidth to about 9.75 KHz.
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KF1Z
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« Reply #61 on: February 17, 2008, 03:52:59 PM »

For those trying to grasp the concept....
This explanation is more eloquent (and correct) than my feeble attempt...

http://www.greenmountainradio.com/SOFTROCK.pdf
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« Reply #62 on: February 17, 2008, 03:57:14 PM »

Frank I do not have 4.99k resistors in this circuit.

The schematic is below.

G


* SRlite6-1.JPG (257.79 KB, 1504x1152 - viewed 621 times.)
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« Reply #63 on: February 17, 2008, 04:20:45 PM »

The resistors in this schematic are R11 and R13. They are now 1 k. Looks like Tony reduced the gain from SR6 the units I bought. You could reduce the gain by putting another 1 K in parallel with each R11 and R13 but first I would reduce the levels going into the sound card on the computer mixer panel to reduce the LO carrier level.
Then bring the RF level back up. I look at the noise floor with nothing connected to the input. Then I connect the radio and adjust things to raise the noise floor about 10 dB. My HPSDR module will do better than -140 dbM noise floor but my crappy RS audio cables pick up hum so run everything a bit higher and set the HPSDR input level higher with internal jumpers.
Any imbalance in the input transformer will jack the carrier up. fc
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« Reply #64 on: February 17, 2008, 04:32:02 PM »

BTW, I just checked my notes. My setup goes into spur mode when the signal gets above -17 dBM. I think your LO is close to that level.
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WBear2GCR
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« Reply #65 on: February 17, 2008, 06:52:24 PM »

Startin to get some focus now...

Well, no one has addressed my question about where to pull off the IF freq in the reciever? Before the IF cans/filters (after the mixa) or somewhere down the line...

...or does this thing have "magic" selectivity using some magic of DSP??

(inquiring mindz want to know)

Seems to me I need two of these thingies for what I am thinkin of?
One for SSB & sync detector. The other for spectrum analyzer.

Btw for those not following the libretto, it seems you really do need a 96kHz soundcard in order to get 96kHz of band into the spectrum display! (thanks for the link Bruce).

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« Reply #66 on: February 17, 2008, 07:39:33 PM »

Bear

I am running mine at 48000 and it works great which is plenty for an IF version. You would want 96 if you were using it as an stand alone receiver and tuning it. Remember you use the radio to tune and the software for the DSP in the IF version.

You would want to tap the IF after the filters to reduce the possibility of overload to the QSD. It will process EVERYTHING that gets to it so using the filters in the widest position will limit what is going into the SR to only the widest filter position.

I have one unit and it works as my detector,SSB and pan adapter all at the same time.
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« Reply #67 on: February 17, 2008, 07:46:45 PM »

Bear,

I'm not totally sure about the best place to pick off your IF....

BUT... I do think the "magic" is there in the DSP.....
I believe the real worry there, is to pick off at a point where you won't load down that stage in your RX....

Frank should chime in here......

..............
space left for Frank
..............



No, I don't think you need 2 units?
Unless they are to go to different RX's ?  
Not real sure what you getting at there....

If only one RX ...
Then you have your spectrum display, and your RX demodulation capability all in one...

And if you use software like WinRad (cool..) or Power SDR (flexradio)
They both have SSB, AM, SyncAM, CW, FM, and a couple others...  oh yes, I think one of them does DRM as well.....









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« Reply #68 on: February 17, 2008, 08:14:35 PM »

Plate of the last IF toob, via a 10 pf or so capacitor would do it Bear.  Re-peak the last IF xformer and yer good to go.  Same drill for a solid state receiver.  You want as much filtering and AGC action BEFORE the IF tapoff.

Or, in the case of your 51J-4 or R-388, there's already a convenient IF output jack that's isolated via a cathode follower.
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« Reply #69 on: February 17, 2008, 08:33:47 PM »

I have tried a number of configurations interfacing to the IF. Presently I right after the second mixer post amplifier. I am using some high performance hardware though. I'm hitting almost 110 db of dynamic range wideband. The set up has the typical Racal  2 6 pole crystal roofing filters in the first IF. I used a pair of 20 kHz filters and the response falls off quickly outside 20 kHz. This set up has the lowest possible gain ahead of the QSD.
As Gary said interfacing after the filters allows more selective positions. I guess it is up to the user. The tighter the bandwidth ahead of the qsd the lower the noise and also the reduced chance of overload. The downside is smaller width of the spectrum display. I also sample at 48 kHz but my lo is further away from Garys allowing up to 15.5 KHz bandwidth. I used a color burst crystal giving me low side conversion with the lo 7.625 kHz. away from 455.
My friend who did our artwork and made the boards interfaced his QSD after the IF filter and left it that way. The R390 has a 16 kHz position so there is plenty to look  at. BTW it is fun to watch the display when the slop buckets park themselves next to us.
Just remember the QSD wants to have a 50 ohm source so a resistive divider of a source follower is required if you are hanging off a high Z interface.
Don't be afraid of using a low end computer sound card it will still work. I'm running a 1 gHz Dell with 500 meg of ram. I'm running about 65% horse power sucking in USB data off the hPSDR. It does not work well sampling at 96 Ksamples and locks up at 192.
I hear the Italians think the world is round.....
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« Reply #70 on: February 17, 2008, 08:41:00 PM »

John,
Any AGC ahead of the QSD screws up the s meter that is why I'm using Racal DF
hardware with no AGC, But it is very wide dynamic range. Close in I am only limited by synthesizer phase noise and find 110 dB of dynamic range is plenty enough at this QTH.  I have a number of pre/post selector options if it becomes a problem.
A way around the AGC problem is to run manual gain so the S meter will give accurate relative results. It is very accurate. 
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N1ESE
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« Reply #71 on: February 18, 2008, 02:33:19 AM »

I just ordered an 80M  SoftRock Lite.  Tony is also throwing in a 30 MHz crystal so I can try and play with it around 75M.  A 30.96 crystal would be much better for full "ghetto" coverage but beggars can't be choosers.

- JT
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N1ESE
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« Reply #72 on: February 18, 2008, 04:12:42 AM »

Would the IF version help to improve the performance and usability of a cheap BA receiver such as an HQ-100 or -110?

- JT
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« Reply #73 on: February 18, 2008, 07:50:26 AM »

yes JT
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« Reply #74 on: February 18, 2008, 07:35:51 PM »

A friend sent me this link which is a gold mine....

http://www.cliftonlaboratories.com/softrock_lite_6_2.htm#Introduction

js
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