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Author Topic: DVB-T Stick as SDR  (Read 113131 times)
WA8RVD
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Posts: 7




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« Reply #45 on: January 02, 2013, 02:25:22 PM »

It's FUN!   It is a low cost toy - lots of fun for very little money!
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WD5GWY
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Posts: 392




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« Reply #46 on: January 02, 2013, 05:29:17 PM »

It's FUN!   It is a low cost toy - lots of fun for very little money!
Exactly !!
james
WD5GWY
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KN0CK
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Posts: 22




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« Reply #47 on: January 02, 2013, 07:57:03 PM »

Hi All,

Just a note since my last post - - I have a design in hand and have ordered parts from Digikey yesterday (1/1/13).  I expect to see those by this weekend.  My design is a different twist on the same upconversion, but puts it in a part of the spectrum that <now> should be pretty quiet these days.  I simplified the output bandpass filter, kept the same LPF <but adjusted the frequency to a new range>, and used the SA612 as the oscillator/mixer, too.  I'm also not using an outboard crystal oscillator to achieve the mix, I'm using the SA612's internal oscillator to make that happen (makes the design a lot easier and less expensive that way, too).  The only active device is the SA612 and it can be run off USB power directly.  The total cost on the parts to make this all happen was less than $15.00, too.  Based on the part selection, the whole thing should fit on a 0.75 x 1.5" circuit board.  Provided that the prototype build goes well, I'll spill the design within a few days after testing and successful final evaluation of the design data and test results occurs.  On the heels of that, a PCB design could be out there soon after - - Stay tuned...

TNX, de Marty, KN0CK
« Last Edit: January 02, 2013, 08:01:29 PM by KN0CK » Logged
KN0CK
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Posts: 22




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« Reply #48 on: January 06, 2013, 08:05:04 PM »

All,

Okay - so I set out with a design, assembled it from the parts that arrived on Friday from Digikey and then gave it a test....Final result:  Success!  I would say that the performance rivals the 'Ham-it-up' board, only requires a low pass filter along with the SA612 mixer, and does not need a output bandpass filter going to the DVB-T stick receiver (my new one is a EZ-CAP receiver).  The only drawback is that I have to use an external +5VDC supply because the oscillator requires it.  I tried an earlier experiment where the SA612 used its internal oscillator and I used a 60 MHz crystal and it was powered off of the USB port and it had decent performance, but there were also too many instances of images at even frequencies (60 MHz and 80MHz) that I ended up using a 125MHz 'can' oscillator off a programmable VFO (that you can buy off EBay for $6.00) and just upconverted using that.  The oscillator is a power hog (draws about 120mA) and will not power from the USB hub I used.  If you're using a powered hub, then the current draw may not affect it.  So, at this time, I'm using an external supply until I can come up with a 120MHz and lower power oscillator.

As I mentioned, upconverting to 125MHz and using the LPF design I'm using the performance of the DVB-T stick and my HF upconverter appears to be equal - if not slightly better - than the 'Ham-it-Up' board.  Also, the final size of my HF upconverter is 0.75" x 1.75" - - MUCH SMALLER than the 'Ham-it-Up' board.  Right now I have the receiver tuned to 75m and I'm listening to various hams yacking away on this Sunday night.  I'm also VERY surprised that it's pulling signals out of the noise pretty decently - something that the 'Ham-it-Up' board had more issues doing.  It's pretty 'self contained', too...The whole thing (DVB-T stick and my HF upconverter) is taking up less than 3" x 0.75" x 0.75".  I reused the PAL connector off the antenna by cutting the cable and attaching it to the output of the HF upconverter.  I have the antenna input just alligator clipped to the upconverter's input at the LPF.

Anyway - I spent the better part of the day playing with it and the design is pretty firm now.  It's a necessity to upconvert into 120MHz or better to avoid overlapping the FM band.  My LPF has a DEEP cutoff (past 70dB) at 88MHz, so as you go up the FM band it just keeps getting better and I'm not getting a lot of noise from FM stations.  At 125MHz it does make tuning a challenge, but I'm not done with the oscillator - - more to follow on that.

Design details - if anyone's interested - do exist.  Post here if you're interested in seeing the design thus far and I'll post that on my website.

73 de Marty, KN0CK
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WD5GWY
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Posts: 392




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« Reply #49 on: January 08, 2013, 04:47:37 PM »

Well, as has been mentioned, the DVB-T dongle is  fun and cheap to play with. I also got
a Ham it UP converter to go along with mine. Finally found the right adapters etc. to hook
the whole thing up. (two came from China in two weeks!!! NO shipping fees, came US Mail)
Using SDR#, I got the whole thing cobbled together and working. I had already been messing
with just the dongle waiting for the adapters to arrive. (my home built up converter, will NOT
have SMA connectors on it!) It is surprisingly sensitive considering how widebanded it is.
Just the dongle by itself was fun.
Adding the upconverter made it better. The toughest part was getting the offset correct so that
SDR#'s frequency readout would be correct on HF. Still not 100% there. But, pretty close.
 Is it as good as my Flex 1500? No, but it surprised me that it heard some things as well as it did.
All in all, I think it is a fun "toy" and having just a bit over $60 in it shipped, it's not bad at all.
(that's including the HamItUp converter too)
 james
WD5GWY
 
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AB1SO
Member

Posts: 1




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« Reply #50 on: January 09, 2013, 05:03:08 PM »


Anyway - I spent the better part of the day playing with it and the design is pretty firm now.  It's a necessity to upconvert into 120MHz or better to avoid overlapping the FM band.  My LPF has a DEEP cutoff (past 70dB) at 88MHz, so as you go up the FM band it just keeps getting better and I'm not getting a lot of noise from FM stations.  At 125MHz it does make tuning a challenge, but I'm not done with the oscillator - - more to follow on that.

Design details - if anyone's interested - do exist.  Post here if you're interested in seeing the design thus far and I'll post that on my website.

73 de Marty, KN0CK


Marty - I would be interested is seeing additional design details or any other information you can post regarding your converter design.

Mark/ AB1SO
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KN0CK
Member

Posts: 22




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« Reply #51 on: January 09, 2013, 05:28:46 PM »

Mark,

Thanks for the post - I'm currently working on the circuitboard design right now and will be posting that as well.  I have the schematic saved in ExpressSCH and will post that along with the PCB design within the next few days once the whole package is done.  As well, I've considered having 10 prototypes made through either OSHPark or ExpressPCB - - right now it looks like OSHPark is probably the cheapest route to make that happen.  I may pull the trigger on that once the board design is done and will have some protos for sale on EBay within the month either integrated with the DVB-T stick (it can fit inside a EZCAP DVB-T radio), or as the stand-alone upconverter board.  Depending on how well that goes, other boards could be produced to keep that going.  Not sure yet - it's kinda early in the game.

The intent of the design was for the HF upconverter design I've come up with (and am listening to on 75m at this very moment - - WORKS EXCELLENT) was to enclose it into an EZCAP or similar DVB-T dongle so it's a complete HF radio in that small form factor.  So that's what inspired the board design I did until 1:00 AM last night (that is 0.75" x 1.75").  However, I did it in ExpressPCB and now need to take that same board design and re-do it in EagleCAD - - it's the only file format the OSHPark accepts.  So I'll have to redraft that board design... : /

Anyway - I'll post the entire package this weekend up on my website and allow you and others to see this, too, and let you know when it's up there...Stay tuned...

de Marty, KN0CK
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KA4POL
Member

Posts: 1966




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« Reply #52 on: January 13, 2013, 10:13:38 PM »

Did you now post your converter circuit? I could not find it.
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KN0CK
Member

Posts: 22




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« Reply #53 on: January 14, 2013, 08:57:44 PM »

Dieter / All,

I've contained the schematic and the board layout to the following weblink:

http://www.kn0ck.com/HFUpconverter/

These pics were just posted in the size they are now - I just threw them up there to get them out so you can look them over.  I'll refine the size and make the overall presentation of the files 'prettier' over the next few days.  What you can do for now is to do a right-click on either image and save it to your desktop.  That way you can size it to anything you want.

Again, data is up there for your review now.  I want to remind everyone that the board layout and schematic are there for INDIVIDUAL HAMS to build from since this design has been verified - - You may use it for YOURSELF with no issue from me at all.  The board and schematic are under copyright to prevent any businesses, domestic or international, to mass-produce this design.  I have the rights to the design as I envisioned it (I realize there are MANY different spins of this out there in the Ham community that use the SA612 - but this is MY design with my component values and the technology I selected (SMD) that were NOT copied from anyone else's design), along with the board design that is ENTIRELY of my own making and vision.  Again, I want to make it abundantly clear that I am NOT preventing a INDIVIDUAL HAM to use the data I have to make his/her own HF Upconverter from my design -- I'm just preventing someone from mass producing them from my idea.

That said.....

I have circuit boards being made at this time and will have 12 of them sometime around the beginning of February.  I will be building 3 final prototypes of this HF Upconverter using the SMD design such that I can fit it into the EZCap DVB_T receiver.  Once I've proven that the final design works acceptably, I'll post the results and then let other Hams know where to buy the boards (may be me since I'll see what the interest is and then go from there).  I may offer a kit or assembled boards, but again, will depend greatly on the interest in the Ham community.

TNX es 73, de Marty, KN0CK
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WV4I
Member

Posts: 136




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« Reply #54 on: January 25, 2013, 07:53:33 AM »

I've been playing with a DVB-T using SDR# and Win 7 32 bit on FM BCB, AM aircraft, and 2M. Receivers designed for those freqs modes far outperform the DVB-T, but then they don't cost $23 plus shipping either. I think that if want HF, better off skipping up converters etc., and get an SDR designed for HF, around $67-$110 kit/built, far better performance, less wires (RFI magnets), etc..
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W0VP
Member

Posts: 6




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« Reply #55 on: January 26, 2013, 06:56:49 AM »

Well, as has been mentioned, the DVB-T dongle is  fun and cheap to play with. I also got
a Ham it UP converter to go along with mine. Finally found the right adapters etc. to hook
the whole thing up. (two came from China in two weeks!!! NO shipping fees, came US Mail)
Using SDR#, I got the whole thing cobbled together and working. I had already been messing
with just the dongle waiting for the adapters to arrive. (my home built up converter, will NOT
have SMA connectors on it!) It is surprisingly sensitive considering how widebanded it is.
Just the dongle by itself was fun.
Adding the upconverter made it better. The toughest part was getting the offset correct so that
SDR#'s frequency readout would be correct on HF. Still not 100% there. But, pretty close.
 Is it as good as my Flex 1500? No, but it surprised me that it heard some things as well as it did.
All in all, I think it is a fun "toy" and having just a bit over $60 in it shipped, it's not bad at all.
(that's including the HamItUp converter too)
 james
WD5GWY
 

My experience is almost exactly the same as James'. I read the article in QST last month and immediately purchased a DVB-T dongle on eBay from China, which arrived in about 10 days I believe. I then ordered the Ham It Up converter and a couple of SMA adapters, which took a week to arrive. Then ordered the correct SMA adapter cables (again from China) to couple the DVB-T dongle to the converter, another two weeks. Finally got everything hooked together and the software downloaded - and by gosh it works! And it really is fun to play with. I haven't compared it yet with the receiver in my IC-706mkIIg or my Sony ICF-2010.

And now I'm starting to think about going to the next level of SDR. I'm not sure yet if I want to go with the Ensemble II receiver, or maybe something like the Ten-Tec 320D. But I am going to start doing some research. In any case just playing around with the dongle/converter combo has re-ignited my interest in amateur radio / SWL which started over 40 years ago with a battery-operated Sears shortwave receiver I received for Christmas. And it didn't take me long to upgrade from that one either!

73,

KC, W0VP
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KE5JPP
Member

Posts: 0




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« Reply #56 on: January 26, 2013, 08:41:53 AM »

And now I'm starting to think about going to the next level of SDR. I'm not sure yet if I want to go with the Ensemble II receiver, or maybe something like the Ten-Tec 320D.

The Ten Tec 320D is not a SDR.  It is a PC controlled receiver.  Even Ten Tec does not call it a SDR.
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W0VP
Member

Posts: 6




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« Reply #57 on: January 26, 2013, 10:57:13 AM »


The Ten Tec 320D is not a SDR.  It is a PC controlled receiver.  Even Ten Tec does not call it a SDR.


I just noticed that myself. From what I've read it looks like a pretty nice receiver, and a definite upgrade from the dongle/converter combo.

KC, W0VP
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K5TED
Member

Posts: 709




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« Reply #58 on: January 27, 2013, 08:03:00 AM »

Last week I took out a second mortgage on my toaster oven, and was approved for over $50 in a loan, which I had planned to invest in one of these high-end DVB-T dongle setups. With this economy, one never knows, but I decided to take the leap and devote some serious resources in hopes it would pan out for me, possibly replacing every radio receiver in the shack...

However, what I've learned here is that if you already own a DVB-T dongle and software to run it, and you are actually having fun playing with it, then you must be doing something wrong. Very soon you will be face to face with the realization you've squandered that princely sum, it's a complete failure and waste of time, and worst, you will be disappointed with the performance. This revelation came just in time to save me from a sure road to skid row. Whew!..

Thank goodness for this venue where almost every little pastime project and casual fun radio endeavor can be vetted, scrutinized, dissected, and shown to be worthless and a waste of time, by our resident experts.
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KE5JPP
Member

Posts: 0




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« Reply #59 on: January 27, 2013, 09:09:58 AM »

Last week I took out a second mortgage on my toaster oven, and was approved for over $50 in a loan, which I had planned to invest in one of these high-end DVB-T dongle setups. With this economy, one never knows, but I decided to take the leap and devote some serious resources in hopes it would pan out for me, possibly replacing every radio receiver in the shack...

However, what I've learned here is that if you already own a DVB-T dongle and software to run it, and you are actually having fun playing with it, then you must be doing something wrong. Very soon you will be face to face with the realization you've squandered that princely sum, it's a complete failure and waste of time, and worst, you will be disappointed with the performance. This revelation came just in time to save me from a sure road to skid row. Whew!..

Thank goodness for this venue where almost every little pastime project and casual fun radio endeavor can be vetted, scrutinized, dissected, and shown to be worthless and a waste of time, by our resident experts.

Yeah, I bet you feel like a real GOOF for spending that exorbitant amount on your Flex 1500 when a DVB-T would have done.  Roll Eyes
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