new TV Tuner Chip, the Si2177

historical

All,

I am using hackrf currently to receive LTE downlink at 15.36Msps.  I have
not specifically tried it at 20Msps, but I believe it should work.  USB2.0
is certainly not the limiting factor for the rtl dongles' sample rate.

Ben
On Sep 21, 2013 5:05 PM, "Nick Foster" <bistromath at gmail.com> wrote:

> As others have tried to explain, this chip does not provide an analog
> output for you to digitize with your soundcard. It turns RF into H.264
> digital video. That's all. There's nothing to digitize and no place to plug
> your soundcard into.
>
> --n
> What is all this talk about USB. High-end Audio Interfaces
> digitize/quantize
> at 192KHz/24bit. Since these new Tuners are almost naked on a surface mount
> board, all that is needed other than a good audio card is a BusPirate to
> control the I2C to get one of these new Analog TV tuner Chips to work as a
> SDR. Since most "Intelligence" in radio is narrow band typically a Voice
> Channel, all that a wideband A/D gives you is a view from 50,000 feet of
> the
> spectrum which is OK for Test and Measurement. I cannot use my TV Dongles
> for most of my (Forward Scatter RADAR) applications because of their low
> resolution, I must use a conventional Scanner because it converts the
> signal
> to Audio. What I need is high definition and narrow band, the current
> Dongles are typically Wide Band low resolution (2Mhz/8bit). This is why a
> Tuner Chip with low noise and demodulated analog output is attractive to
> me,
> it is a complete solution.
>
> -----Original Message-----
> From: osmocom-sdr-bounces at lists.osmocom.org
> [mailto:osmocom-sdr-bounces at lists.osmocom.org] On Behalf Of Leif Asbrink
> Sent: Saturday, September 21, 2013 4:38 PM
> To: osmocom-sdr at lists.osmocom.org
> Subject: Re: new TV Tuner Chip, the Si2177
>
> Hi Adam,
>
> > > > The bandwidth of the I/Q pair is too large to be transmitted over
> > > > USB for the reception of TV signals. After demodulation the
> > > > bandwidth is lower so it would (marginally) fit an USB interface
> > > > if we talk about traditional analogue TV. For digital TV the
> > > > bandwidth reduction by the decoder is much larger.
> >
> > Is that correct?  From what I can find, an analogue TV signal has a
> > bandwidth of around 6-8MHz.
> Yes.
>
> > The HackRF is an SDR that works over
> > USB2.0 and can capture a chunk of RF spectrum up to 20MHz, which
> > should be ample for one analogue (or even digital) TV signal, perhaps
> > even two if the channels are close enough together.
>
> I was under the impression that the USB channel was the reason that the
> highest sampling rate I was aware of in continous mode is 4 MHz
> (QS1R) Now, I did not think of the fact that for the dongle we need only 8
> bit while normal SDRs use 16 bit so with my assumption the maximum sampling
> speed would be 8 MHz. To receive 6-8 MHz bandwidth one would need to sample
> quite a bit higher. Surely one could apply digital filters but even so a,
> substantial amount of oversampling is needed.
>
> Are you sure HackRF really can send 20 MHz of bandwidth over USB 2.0
> continously? Where did you find that info? (Seems I should try to push SDR
> manufacturers who use USB 2.0 to supply modes with higher sampling
> rates...)
>
> 73
>
> Leif
>
> -----
> No virus found in this message.
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>
>
>
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