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.
I would not be surprised if the Si Labs chips have an option to
send unprocessed I/Q data to the USB. Somebody should approach them
and ask:-)
73
Leif / SM5BSZ
OK, for those who do not grasp the principle of
On-chip Demodulation, SILICON LABS is manufacturing a spectrum of advanced Tuners, one of
which may suit the mindset of those who buck the idea of a Demodulator on chip. There is
one that demodulates Analog TV alone, one that demodulates Digital TV alone, and one that
does both. Ask yourself this question... Why is there an A/D converter chip on the current
Tuner Dongles? Would it not be better to convert the unadulterated demodulated Digital
stream directly into a 192k/24bit audio card (or just 48k/16bit)? This new capability
tells my Engineering mind that the noise floor would go way down, which is the main
deficiency with the current cheap TV Tuner Dongles, keeping them from being used for low
level narrowband reception.
http://www.silabs.com/Support%20Documents/TechnicalDocs/Si2157-short.pdf
-----Original Message-----
From: osmocom-sdr-bounces(a)lists.osmocom.org
[mailto:osmocom-sdr-bounces@lists.osmocom.org] On Behalf Of Jay Salsburg
Sent: Thursday, September 19, 2013 12:21 PM
To: osmocom-sdr(a)lists.osmocom.org
Subject: new TV Tuner Chip, the Si2177
I just received a Product Announcement from SILICON LABS. There new TV Tuner Chip, the
Si2177, appears to be able to demodulate Analog TV directly on the chip without software.
If I am not mistaken, this function is a new feature in TV Tuner Chips, which may provide
a much better SDR than current TV Tuner Chip Dongles, especially when it comes to noise
performance. It also eliminates almost all external components. RF Input Frequency Range -
42 to 870 MHz
Si2177 5th Generation Silicon TV Tuner ICs
http://www.silabs.com/Support%20Documents/TechnicalDocs/Si2177-short.pdf
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