Digital Signal Processing

[K9ACT]

Having worked with SDR receivers for a year now, it is becoming obvious that putzing around with analog processors and EQ's for transmitter audio is like tying to get a nice tone out of a spark transmitter.

Googling the subject produces thousands of pages of how to, tutorials, IC's and books but not a single plug and play product of any sort.  It's like DSP was just invented and no one has done anything with it yet.

Someone suggested MFJ and they do have a product but it is designed for receiver audio enhancement not input to a modulator. 

Can anyone point me to something that would be of interest?

js 

[kc2ifr]

EQ's for transmitter audio is like tying to get a nice tone out of a spark transmitter.

I think u should rethink that statement.
There are some really nice analog processors out there. I have 2 of them and they sound very good.
Both formats have there good points and bad points.
I have heard quite a few "digital" processors that sound like sh$#.
Its all in the setup and knowing what u are looking for and how to set up the equipment.......no more and no less!

Bill

[Steve - WB3HUZ]

If you can't make a transmitter sound good with analog audio gear, it won't sound any better with digital audio gear. TANSTAAFL.

[K9ACT]

If you can't make a transmitter sound good with analog audio gear, it won't sound any better with digital audio gear. TANSTAAFL.

Your helpful response is based on a false presumption or at least is off on a tangent.

Sounding "good" is like beauty (in the eye/ear of the beholder) but I had something else in mind but didn't make myself clear.

Digital processing gives near absolute control over some aspects of sound and the only one I am interested in at the moment is bandwidth.

Take a look at the attached screen shot of a friend's Flex 5000 taken off my S40B PwrSdr display.

That is how I want my signal to drop off where I choose and I know of no other way to do it.

I am pretty happy with my audio chain except for the 3db/octave roll off of the high end.

All I really want is a low pass filter with the sort of roll off he has on his Flex.

js

[ka3zlr]

Welp,... First, when I Operated I always followed Dons Procedure..Quiet Your Audio Drive an Turn up the Wick...it's a good procedure to follow...just for starters..

Now, there's a myriad of processing equipment out there... you can get lost in that stuff and spend needless...amounts of money...for a simple idea...

All that's required is a Clean Presence...and it's simple enough to do...I used the rat shak Electret Condenser mic element...and a small EQ circuit I built i followed off of here but I forget who posted it an where it is ..it's been so long...it's a simple circuit to build and it werks great but i can't remember who posted it...was it Bob or Stevie..or Ed..man i can't remember..Dang...

I'll find it's here somewhere..

[WB2YGF]

All that's required is a Clean Presence...and it's simple enough to do...I used the rat shak Electret Condenser mic element...and a small EQ circuit I built i followed off of here but I forget who posted it an where it is ..it's been so long...it's a simple circuit to build and it werks great but i can't remember who posted it...was it Bob or Stevie..or Ed..man i can't remember..Dang...

I'll find it's here somewhere..

Is this what you are looking for?

http://members.cox.net/w1aex/Mic.html

[Steve - WB3HUZ]

Sorry. No offense intended. I replied to your comment.

Having worked with SDR receivers for a year now, it is becoming obvious that putzing around with analog processors and EQ's for transmitter audio is like tying to get a nice tone out of a spark transmitter.

No one can be helpful if you don't clearly articulate what help you want. Now that we've established that your are looking for a lowpass filter with a sharp roll off, there are many options, both analog and digital.

Almost any analog EQ will give you far more than 3 dB octave rolloff. The CRL processors have a very sharp LP filter on the output. I could scan the schematic if you'd like.

The Behinger 8024 might be worth a shot, if you want to go digital. Its "True Response" set up lets you dial up almost any eq curve you want.

The Behringer DEQ1024 is a less expensive option. It has sweepable high and lowpass filters. So do many analog eqs.

You could also use your computer. Here's just one example. I don't recall the name but there is a SW package that will do processing too.

http://www.blazeaudio.com/products/webeq.html

If you can't make a transmitter sound good with analog audio gear, it won't sound any better with digital audio gear. TANSTAAFL.

Your helpful response is based on a false presumption or at least is off on a tangent.

Sounding "good" is like beauty (in the eye/ear of the beholder) but I had something else in mind but didn't make myself clear.

Digital processing gives near absolute control over some aspects of sound and the only one I am interested in at the moment is bandwidth.

Take a look at the attached screen shot of a friend's Flex 5000 taken off my S40B PwrSdr display.

That is how I want my signal to drop off where I choose and I know of no other way to do it.

I am pretty happy with my audio chain except for the 3db/octave roll off of the high end.

All I really want is a low pass filter with the sort of roll off he has on his Flex.

js

[K9ACT]

Sorry. No offense intended. I replied to your comment.

None taken... just getting a little blustering in.

>The Behringer DEQ1024 is a less expensive option. It has sweepable high and lowpass filters. So do many analog eqs.

Right to the point.  After changing my search from Digital Signal Processing to Digital EQ,  I found plenty to read.

After a bit of reading, I pretty much decided on that one but one of the last pages in the manual was a show stopper.  Note the word "analog" in the EQ spec attached.

After touting the glories of digital, what on earth does this mean?

>You could also use your computer. Here's just one example. I don't recall the name but there is a SW package that will do processing too.

http://www.blazeaudio.com/products/webeq.html

I will take a look.  Someone sent me to Rocky as in Soft Rock but it only goes to 3kc as near as I can tell.  It's a slop bucket world.

Thanks,

js

[ka3zlr]

All that's required is a Clean Presence...and it's simple enough to do...I used the rat shak Electret Condenser mic element...and a small EQ circuit I built i followed off of here but I forget who posted it an where it is ..it's been so long...it's a simple circuit to build and it werks great but i can't remember who posted it...was it Bob or Stevie..or Ed..man i can't remember..Dang...

I'll find it's here somewhere..

Is this what you are looking for?

http://members.cox.net/w1aex/Mic.html

That's it right there..."The 5 Dollar Mic"...and it werks great...

No RF issues..No Dog chasing the tail looking for the sweet spot..

I hate to bust anybodies bubble...Behringer stuff is Junk...save your money...i know I have tried their stuff out and it don't last...

[kc2ifr]

...Behringer stuff is Junk...save your money...

Im not going to say a word.................(but thank u!)......

Bill

[ka3zlr]

 

looks both directions..( yer welcome Bill ) i might add you have a FB signal into the Zed.L.R. Cellar Dweller Underground Radio Station...so there you are...

[KD6VXI]

Having worked with SDR receivers for a year now, it is becoming obvious that putzing around with analog processors and EQ's for transmitter audio is like tying to get a nice tone out of a spark transmitter.

Googling the subject produces thousands of pages of how to, tutorials, IC's and books but not a single plug and play product of any sort.  It's like DSP was just invented and no one has done anything with it yet.

Someone suggested MFJ and they do have a product but it is designed for receiver audio enhancement not input to a modulator. 

Can anyone point me to something that would be of interest?

js 

If you would like to use your computer, voice shaper (for WinTel Windows platforms) has EQ, Gating, processing, etc built in.

Freeware.

NOTHING compared to using pro studio quality processing on your audio chain (I have a windows laptop dedicated to station audio.  2 channel built in sound card, ASIO drivers for it).  Nobody can tell the difference.

You can also find a gentleman in Italy that has a processor program that mimics the popular AM and FM station pro boxes, including Omnia.  I haven't tried it, but it is very popular with the pirate stations in Europe.

Myself, I use either Adobe Audition 3.0 or Reaper, Izotope plugins for multiband compression and a broadcast plugin that does final processing.  Allows for negative peak limiting, compression, etc... And then on the output I run a phase adjuster to allow for > positive than negative peaks, regardless of the symmetry of the "voice" on the air.

2nd channel of the sound card allows for station monitoring so you can pretty much record everything that happens, both sides of a QSO, depending on how much hard drive space you have..... BUT, you don't need a LOT of resolution (sampling rate can be low) for RX, unless you want "hifi" RX record.

I have a sample audio chain for Reaper, should you want a copy.

ALSO, Mighty Fine Junk  DOES have a transmit audio processor, but it is analog, not digi...  EQ, gating and preamp, IIRC.

--Shane

[W1AEX]

Here's another vote for Voice Shaper, which Shane mentioned. As far as I know, it's the only freeware application that will do "real-time" voice processing. As Shane mentioned, it has a 7 band EQ between 30 Hz and 6000 Hz and offers very effective compression and limiting. It also offers a brick wall audio frequency filter should you wish to employ it for de-essing. Of the short list of programs I played with, VShaper had the least amount of latency and was the most effective in my opinion. One caveat is that I have had no luck using Vshaper with any sound cards newer than the Creative Sound Blaster PCI architecture series.

http://www.dxatlas.com/VShaper/

I fooled around with the trial version of the Romac Software Equalizer which is directed at the amateur community and it was a very nice package. The system I used it with was marginal and seemed to produce some artifacts. I can't fault the software for this as everything on that system seemed to have the same problem. The biggest issue I saw with their package was that the 10 band EQ was geared for narrow band modes with adjustment between 50 Hz and 3200 Hz. The range may have been adjustable so it might be interesting to look at the trial version:

http://www.romacsoftware.com/

I also messed around with an older version of Graphic Equalizer Studio. It's a real-time 1/3 octave graphic equalizer that works beautifully, but offers no limiting or compression. I see that their newer versions do have compression.

http://pas-products.com/eqstudio.htm

I downloaded a trial version of the Blaze 5 band EQ but never installed it, so I have nothing to report there. It's certainly cheap enough at around 20 bucks.

At any rate, I like free stuff even better than cheap stuff, so if anyone spots anything else out there I'd be interested too!

73,

Rob W1AEX

[kc2ifr]

Jack......
wink.....wink......nod.....nod.........
Thanks..

[K9ACT]

Here's another vote for Voice Shaper, which Shane mentioned. As far as I know, it's the only freeware application that will do "real-time" voice processing. As Shane mentioned, it has a 7 band EQ between 30 Hz and 6000 Hz and offers very effective compression and limiting.

Thanks for the nudge.  I downloaded that yesterday and dismissed it because it only went to 3kc.

Just took another look and sure enough, 3 more 1kc tics.

Thanks,

js

[WB2YGF]

I hate to bust anybodies bubble...Behringer stuff is Junk...save your money...i know I have tried their stuff out and it don't last...

Yeah, but does it work, and what "don't last" about it?

[Ian VK3KRI]

Welp,... First, when I Operated I always followed Dons Procedure..Quiet Your Audio Drive an Turn up the Wick...it's a good procedure to follow...just for starters..

Now, there's a myriad of processing equipment out there... you can get lost in that stuff and spend needless...amounts of money...for a simple idea...

All that's required is a Clean Presence...and it's simple enough to do...I used the rat shak Electret Condenser mic element...and a small EQ circuit I built i followed off of here but I forget who posted it an where it is ..it's been so long...it's a simple circuit to build and it werks great but i can't remember who posted it...was it Bob or Stevie..or Ed..man i can't remember..Dang...

I'll find it's here somewhere..

Personally, I have tried this, and you can get a nice sounding signal, BUT, it hasn't got the punch of a well processesd signal.  If I playback a unprocessed recording of myself with my normal mic into my TX on 160 , just hitting 100%  and then listen on a AM broadcast radio tweaked up to 160, it just sounds 'small' compared to what you can hear when you tune down into the broadcast band.  No matter how much I tweaked and EQed it just sounded 'small'

Eventually adding a DSP based bandpass filter/multiband compressor-clipper / equaliser / look ahead limiter evened things up quiet a bit, but I'm still behind the broadcast stations. 

Now some people complain about excessive processing,  which is fine if those listening have 60dB+ S/N   but most of the time that just isn't the case.  Done within limits, better processing equals better audio at the far end.
                                                                                                                   
                                                           Ian VK3KRI

[ka3zlr]

I hate to bust anybodies bubble...Behringer stuff is Junk...save your money...i know I have tried their stuff out and it don't last...

Yeah, but does it work, and what "don't last" about it?

Buy it and Find Out...Junk Pots, Junk Power Supplies, No RFI proofing, Junk Cabinetry....in other words very cheap copies of much better circuitry...open one up and Look...but it werks Jack..?..yea for how long...

73
Jack.

[ka3zlr]

Welp,... First, when I Operated I always followed Dons Procedure..Quiet Your Audio Drive an Turn up the Wick...it's a good procedure to follow...just for starters..

Now, there's a myriad of processing equipment out there... you can get lost in that stuff and spend needless...amounts of money...for a simple idea...

All that's required is a Clean Presence...and it's simple enough to do...I used the rat shak Electret Condenser mic element...and a small EQ circuit I built i followed off of here but I forget who posted it an where it is ..it's been so long...it's a simple circuit to build and it werks great but i can't remember who posted it...was it Bob or Stevie..or Ed..man i can't remember..Dang...

I'll find it's here somewhere..

Personally, I have tried this, and you can get a nice sounding signal, BUT, it hasn't got the punch of a well processesd signal.  If I playback a unprocessed recording of myself with my normal mic into my TX on 160 , just hitting 100%  and then listen on a AM broadcast radio tweaked up to 160, it just sounds 'small' compared to what you can hear when you tune down into the broadcast band.  No matter how much I tweaked and EQed it just sounded 'small'

Eventually adding a DSP based bandpass filter/multiband compressor-clipper / equaliser / look ahead limiter evened things up quiet a bit, but I'm still behind the broadcast stations. 

Now some people complain about excessive processing,  which is fine if those listening have 60dB+ S/N   but most of the time that just isn't the case.  Done within limits, better processing equals better audio at the far end.
                                                                                                                   
                                                           Ian VK3KRI

I guess you already Know what the other Amateur wants to listen To First..? make sure your signal is 100% copyable at all times..under QSB the Psycho-Acoustic effected audio goes in the toilet fast..

It doesn't matter to me, my comment was on Simplicity and getting the job done cheaply and maintaining a Clean Signal..without all the Tail chasing that comes with the Knobs...I like looking at all the Amateur stations with Lots of Racked EQ's..and then I sit back and consider well, I like to build things and monitor the effect..and I like the microphone preamping going on...and boy do some of these guys Know how to drive the pants off their balanced modulators...Wow..

I Much prefer Dons Method...

73
jack.

[Ian VK3KRI]

I guess you already Know what the other Amateur wants to listen To First..? make sure your signal is 100% copyable at all times..under QSB the Psycho-Acoustic effected audio goes in the toilet fast..

It doesn't matter to me, my comment was on Simplicity and getting the job done cheaply and maintaining a Clean Signal..without all the Tail chasing that comes with the Knobs...I like looking at all the Amateur stations with Lots of Racked EQ's..and then I sit back and consider well, I like to build things and monitor the effect..and I like the microphone preamping going on...and boy do some of these guys Know how to drive the pants off their balanced modulators...Wow..

I Much prefer Dons Method...

73
jack.

Doesn't Don run a BL40?

I don't mind what audio gear any one uses. However the audio you stick on your carrier is part of the personality of your station. Audio processing gear is as much a waste of money as any Ham gear. If your happy with a good quality mic straight into a lo distortion modulator, that's fine by me, and getting a good sounding signal out of that setup is pre-requisite for going any further.
But, theres a heap of audio stuff out there you can play with. Some of its good, some of its bad. I like playing with it, and I am convinced it gives me a few extra dB when the S/N gets down, so I'll keep tweaking my DSP.

                                                                    Ian VK3KRI
 

 

 

[kc2ifr]

I run the BL-40 and LOVE it.

Bill