OsmoSDR - turn a USB TV tuner into an SDR

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bezking

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Looks like someone has figured out that USB TV-tuners can be repurposed into wideband SDR receivers:

http://sdr.osmocom.org/trac/wiki/rtl-sdr

From that page:
The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, sticks that use the Elonics E4000 offer the best range (64 - 1700 MHz).
It looks like this project is in it's early stages (they claim to have been successful with TETRA and "GMR") but I figured some folks here would be interested...
 
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slash

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It looks very promising and prices have already gone up for these devices.
These have the potential to be a big game changer and never require an expensive scanner again.

Slashdot ran an article on them, too. Get 'em while they last, because I don't think they will be making new production runs with this feature.
 

aaknitt

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I finally got mine today and did some playing around using GNUradio. It actually works better than I expected for a $20 tuner. Within a couple hours I had it receiving four VHF radio channels within a 1 MHz bandwidth simultaneously. I could have probably done a lot more than four channels but that's all I've tried so far. I think it could do up to a 4 MHz bandwidth in theory but I haven't done much playing around yet.

This could be really interesting for streaming audio feeds....with a single device you could stream a number of different channels without needing to scan....it can receive as many channels as you want at the same time within the limits of your computer's ability to process them and the receiver bandwidth.

The only downside is the very limited dynamic range, which I knew about up front. Strong signals force the receiver to reduce gain, which will swamp out weaker signals. Overall though it's really neat to play with.

Eventually I'd like to get it integrated with TwoToneDetect so that you could monitor multiple fire paging frequencies at the same time with a single $20 device. That's a long ways out though, I'm still learning GNUradio, and it has a really steep learning curve.

Andy
 

ki4gyw

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Did you implement your 4 ch receive using grc? I am trying to accomplish a 4 change rx and pipeing it to dsd
 

aaknitt

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Did you implement your 4 ch receive using grc? I am trying to accomplish a 4 change rx and pipeing it to dsd
Yes, I can send you the flow graph if you want, just send me a PM with your email address. I'd also be interested in seeing how you pipe the output to other programs, as I'd like to do the same thing.

Andy
 

bezking

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Andy, if you could send it my way as well (bezking -at- radioreference.com) it would be appreciated.

I got mine through digitalhome88 on eBay. It was $30 but I opted for a smaller version. It took 15 days to arrive from China (it took a few days for them to actually ship), but zero complaints. These units are tiny but work excellent - the jack fits very snug on the antenna, and has a remote (of little use to me).

DVB-T digital Radio SDTV HDTV Win7 XP Realtek RTL2832U Elonics E4000 P160 | eBay
I just went for one of these. I've finally found an excuse to get started with GNU Radio... :)
 

ki4gyw

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How about a DSD Block for gnuradio? Now that would rock! OP25 is nice if you can get it up and working!
 

slash

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How about a DSD Block for gnuradio? Now that would rock! OP25 is nice if you can get it up and working!
Seconded -- this is the primary reason I bought this device because I know it's going to happen. I'm so glad I didn't shell out dough for a new P25 scanner. I'm really looking forward to trying to decode EDACS Provoice with this thing too.
 

aaknitt

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Seconded -- this is the primary reason I bought this device because I know it's going to happen. I'm so glad I didn't shell out dough for a new P25 scanner. I'm really looking forward to trying to decode EDACS Provoice with this thing too.
Be careful, the more I play with this thing the more I think it's just a gateway drug to high dollar SDR equipment :D

I haven't had much success running at higher sampling rates than 1 MHz. I think the limitation is my computer. 1 MHz of bandwidth is pretty good at VHF, but at 800 MHz it's not enough to follow an entire trunked conversation without retuning.

The dynamic range issue will also limit this device's usefulness for any "serious" applications, since a strong local signal will wipe out anything else in the receiver bandwidth as the AGC adjusts. Even for streaming this could be an issue.

Still great to play with and learn from though.

Andy
 

slash

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I haven't had much success running at higher sampling rates than 1 MHz. I think the limitation is my computer. 1 MHz of bandwidth is pretty good at VHF, but at 800 MHz it's not enough to follow an entire trunked conversation without retuning.

Andy
Yeah - I know I'm being optimistic for just one of these devices, but even if I could manage to get a few of these things to work in tandem, I'd be thrilled. Even if I need to still use a traditional scanner for trunking, this eliminates my need to find a second one and go through the hassle of making a discriminator tap (for ProVoice).
 

bezking

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So the device arrived today from China. I followed this relatively simple tutorial and was up and running in no time.

With the crappy included antenna and a metal cookie sheet, I'm able to copy aircraft communicating with JFK Tower (but not comms from the tower) on 119.1 AM. The quality's not /amazing/, but for under $20 in parts and free software it's really not bad at all.

Here's a screenshot of it in operation: http://i.imgur.com/J6Hbi.jpg
 
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n9mxq

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So the device arrived today from China. I followed this relatively simple tutorial and was up and running in no time.

With the crappy included antenna and a metal cookie sheet, I'm able to copy aircraft communicating with JFK Tower (but not comms from the tower) on 119.1 AM. The quality's not /amazing/, but for under $20 in parts and free software it's really not bad at all.

Here's a screenshot of it in operation: http://i.imgur.com/J6Hbi.jpg
Got mine yesterday, followed the same directions.. Apparently my Laptop doesn't have the horsepower for SDR.. Will have to set it up on my quadcore desktop and see what happens.
 

bezking

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Yeah, I originally tried running the software in a VM, and the performance was pretty bad because the VM only had 2GB RAM. It works fine for me on my desktop which has a 3.10GHz AMD dual-core 64gb processor and 8GB RAM.
 

k8mcn

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what "device" hint

what "device" hint are you guys using, RTL readlen=8192 tuner=e4??thanks
 
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DaveNF2G

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I might have missed this in the thread, but is anyone doing anything with this under Windows?

OK, I have edited out my original second question after going to eBay and realizing what products are being discussed. Now I have a new question. There are many USB TV tuners on the market. Are they all suitable for such repurposing?
 
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