Warning not an E4000 (has R820T)

[mr.sneezy]

Hi Guys.

I'm a newbie in SDR terms but got a lot of non-SDR radio system and PC experience. Decided to dabble in SDR to see what the fuss is about, but my first dongle  purchase was not as expected (not that unusual on Ebay these days). I'll be emailing the vendor as I guess it's useless for SDR unless it's just too new to have been considered.

Ebay listing is this:

RTL-SDR FM+DAB USB DVB-T Dongle DVB-T STICK RTL2832U+e4000 new

Pictures of it.

[jdow]

That is NOT, repeat NOT an E4000 chip pictured.

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[Adam Nielsen]

> That is NOT, repeat NOT an E4000 chip pictured.

On the plus side, you got a free device since the seller sent you the wrong
item. And support may get added one day, it's just not usable yet.

I can't find out much about the R820T tuner - does anyone have a datasheet? I
have contacted a few sellers on eBay and Rafael Micro, but I'm not holding out
much hope for a response.

Cheers,
Adam.

[Ballymunboy]

All I found on the R820T was the single-sheet Product Brief [1]  and a Press Release from Feb 2011 about the tuner series. [2]

There is an Evaluation Kit listed on the Rafael Micro website [3]  and a reference to a PDF Application Note, but the link(?) is missing (if it was ever there):

DVB-T Tuner Module Reference Design：Application Note(PDF)

Kit x 1

Document：Include Datasheet, Reference Schematic, Gerber

An email to sa...@rafaelmicro.com (the listed email address) just bounced with an SMTP 550 error (Mailbox Not Available)

cheers, a

[1] http://www.rafaelmicro.com/downloads/R820T.pdf
[2] http://www.rafaelmicro.com/News%20release/%E5%AE%8F%E8%A7%80%E5%BE%AE%E9%9B%BB%E5%AD%90%E6%96%B0%E8%81%9E%E7%A8%BF_%E8%8B%B1_%2020110201.pdf
[3] http://www.rafaelmicro.com/Applications.htm

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[linagee]

It says I2C bus on the R820T datasheet you linked to. So my guess is, you'd need to sniff the I2C bus, run the regular application at a known frequency, do some serious reverse engineering of their protocol to the tuner, add bits into existing e4000 code, test and see if it works. (R820T is just the tuner and not the ADC/USB/etc, so most of the work should already be done for you in the RTL2832U code.) Good luck! If you had the evaluation kit, this would probably help 1,000% if you sent it to the appropriate developer. (Not me, I'm just an armchair SDR-er.) Even without an evaluation kit though, its just a matter of time before the R820T is figured out.

linagee

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[Ballymunboy]

On Sat, Sep 1, 2012 at 7:38 AM, linagee <lin...@gmail.com> wrote:

It says I2C bus on the R820T datasheet you linked to. So my guess is, you'd need to sniff the I2C bus, run the regular application at a known frequency, do some serious reverse engineering of their protocol to the tuner, add bits into existing e4000 code, test and see if it works. (R820T is just the tuner and not the ADC/USB/etc, so most of the work should already be done for you in the RTL2832U code.) Good luck! If you had the evaluation kit, this would probably help 1,000% if you sent it to the appropriate developer. (Not me, I'm just an armchair SDR-er.) Even without an evaluation kit though, its just a matter of time before the R820T is figured out.

linagee

That crossed my mind too!   Dunno what speed the i2c bus is running at, but the open hardware PIC24-based BusPirate [1] can reportedly sniff i2c traffic at 100kHz (very slow).  But probably the i2c bus between the RTL2832U and the R820T is running much faster and a proper logic analyser is needed.
 
Reverse engineering the R820T could be a long job. According to the datasheet for the similar Elonics E4000 tuner, posted by Ben Ryan [2],  the E4000 has over 70 registers, holding a range of datatypes including arbitrary scalars.

cheers, a

[1] http://dangerousprototypes.com/docs/I2C
[2] https://groups.google.com/forum/#!msg/ultra-cheap-sdr/zXhBfiYdxf4/L2r108nnyXQJ

[mr.sneezy]

Hi guys,

I got a reply back from the vendor. He offered me a $3 refund on the $16 purchase, so no free dongle for me (but I have asked him to raise his refund offer).

I did try to buy one from my LHS's first, but typically they were out of stock of everything that is supposed to have a E4000. 

I guess if the E4000 chipped dongles are hard to get or now out of production, then adding the new tuner chips is the direction of the future of UC-SDR.

On a more positive thought, I do have access to a high speed logic analyser, and maybe a fast I2C protocol analyser as well. 

Martin

[Adam Nielsen]

> I got a reply back from the vendor. He offered me a $3 refund on the $16
> purchase, so no free dongle for me (but I have asked him to raise his refund
> offer).

Did you buy it from eBay? Just flag it as the wrong product. In my
experience all sellers readily offer to send you the correct replacement for
free to avoid negative feedback. It is after all their fault for sending the
wrong item (or for deliberately trying to mislead you) so you shouldn't be
left out of pocket.

> I guess if the E4000 chipped dongles are hard to get or now out of production,
> then adding the new tuner chips is the direction of the future of UC-SDR.

I'm sure this is where it's heading, I just hope these new tuners are at least
as good as the E4000. On paper they don't seem quite so good. Apparently
nobody has bid enough for Elonics' IP yet, so no new E4000s appear to be on
the way.

> On a more positive thought, I do have access to a high speed logic analyser,
> and maybe a fast I2C protocol analyser as well.

This is so much effort to achieve I'd go so far as to say it's probably not
worth the effort. Even the E4000 wasn't reverse engineered as it's far too
complex (only the RTL2832's undocumented SDR mode was discovered by reverse
engineering.)

Cheers,
Adam.

[mr.sneezy]

Yes it was Ebay. I settled for less than a full refund, but frankly I'm just over haggling for a few $ either way (done it before). I'll just send some honest feedback.

I guess step one with this device is going to be getting full datasheet and application note. Though if the chip is a 'flash in the pan' and not going to be popular then there is little point.

I tried the dongle out today in it's DTV mode and then also the analogue FM radio mode. DTV reception was OK, but in analogue FM mode it has VERY good sensitivity. It worked inside my tin shed with the door shut, where most FM radios won't.

Cheers,

Martin