new TV Tuner Chip, the Si2177

Sylvain AZARIAN sylvain.azarian at gmail.com
Sun Sep 22 16:50:23 UTC 2013


My personal tests on usb2 with Windows or Linux show a limit around 35
mbytes/sec (tested with Cypress fx2 or fx3)

Sylvain
Le 22 sept. 2013 18:36, "Ben Wojtowicz" <bwojtowi at gmail.com> a écrit :

> 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.
>> Checked by AVG - www.avg.com
>> Version: 2013.0.3408 / Virus Database: 3222/6687 - Release Date: 09/21/13
>>
>>
>>
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