Hi Kyeong, Thanks for all the answers! Regards, Adrian
On August 25, 2018 8:31:57 AM UTC, Kyeong Su Shin <kss...@postech.ac.kr> wrote: >Hello Adrian, > > >The USB interface is integrated in the RTL-SDR chip (RTL2832U), so it >cannot be replaced (as far as I know). > > >In theory, USB 2.0 can support faster data rates (HackRF does 16 MS/s - >20 MS/s with USB 2.0 8 bit I-Q). As Ron mentioned, it is due to the >cost reduction. > > >Regards, > >Kyeong Su Shin > > >________________________________ >보낸 사람: Adrian Musceac <kanto...@gmail.com> 대신 Discuss-gnuradio ><discuss-gnuradio-bounces+ksshin=postech.ac...@gnu.org> >보낸 날짜: 2018년 8월 25일 토요일 오후 5:13:09 >받는 사람: discuss-gnuradio@gnu.org; Ron Economos >제목: Re: [Discuss-gnuradio] MAKING A NTSC TV RECEIVER > >Hi Ron, > >So in theory, replacing the USB2 chip with a USB3 would allow access to >the full sample rate, or is there some other internal limitation? > >Regards, >Adrian > >On August 25, 2018 8:06:20 AM UTC, Ron Economos <w...@comcast.net> >wrote: > >The maximum Transport Stream rate of DVB-T is 31.67 Mbps, so the USB >interface only needs to deliver 4 MB/s. Since you need two 8-bit >samples in IQ mode, it's 2 Msps. > >Ron > >On 08/25/2018 12:44 AM, Adrian Musceac wrote: >Hi Marcus, > >You're right about the RTL sample rate, but I'm curious about why it is >so small. >Is it the bus speed? The ADC is obviously fast enough for DVB-T2. > >Regards, >Adrian > >On August 24, 2018 7:42:17 PM UTC, "Müller, Marcus (CEL)" ><muel...@kit.edu><mailto:muel...@kit.edu> wrote: > >Hi Martin, > >internally, the RTL dongles are fast enough to capture full DVB-T (not >-T2) channels, and demodulate, and decode them, and deliver the video >stream to the host. However, RTL-SDR can't use that mode - it uses a >"bypass the whole Digital TV specific stuff" mode and directly passes >IQ samples through USB. > >In that mode, it simply can't do more than 2 or 3 MS/s (can't >remember), which isn't enough to cover 6 MHz - so everyone's right, you >can basically receive the AM black/white info at a partial bandwidth of >the ca 5 MHz of the luma signal, but you won't get any color >information that way, or audio with the same receiver as you do video. > >Cheers, >Marcus > >On Fri, 2018-08-24 at 12:22 -0500, Martin McCormick wrote: > > First, I will talk about the things I know for sure. The > NTSC analog system as well as Pal systems in a lot of the rest of > the world had a lot in common with eachother. Both systems > transmitted an AM video signal in Vestigial single sideband mode > such that the carrier frequency was always about 1.25 MHZ above > the start of a channel. NTSC systems in the Americas also > transmitted an audio carrier in FM which was always 4.9 MHZ above > the video carrier. Pal systems used exactly the same type of > transmissions except that the 625-line video at 25 frames per > second made a slightly wider spectrum such that the audio and > video carriers were separated by 5.x MHZ, making each Pal channel > 7 or 8 MHZ wide. > > As others have suggested, you could probably get a > monochrome fuzzy image if you can get your sound card to sample > fast enough. You can also decode the mono sound by setting your > RTL receiver to behave just like a FM broadcast receiver but set > the frequency to whatever the video carrier frequency is plus 4.5 > MHZ. if the video carrier is 55.250 MHZ, the audio will be at > 59.75 MHZ. The deviation is 75 KHZ unlike FM radio which is 150 > KHZ. > > That would be a good simple test to see if you are > receiving the channel at all. > > I am guessing that since the RTL chips were designed for > the European television market for cable and over-the-air > broadcasts, they can be sampled extremely fast since the digital > channels still take up the same bandwidth as their analog > ancestors. > > Martin McCormick WB5AGZ > > Anders Hammarquist <i...@openend.se><mailto:i...@openend.se> writes: > > In a message of Fri, 24 Aug 2018 10:27:40 +0200, "Ralph A. Schmid, > dk5ras" writes: > > Hi Andres, > > just had a short look: doesn't NTSC use a nearly 6 MHz > bandwidth? > > Best regards, > Marcus > > > Yes, no way with the RTL to catch NTSC, it does in SDR mode only > 2.smth > > > MHz bandwidth. > > Actually, you should be able to get a picture. The horizontal > resolution > will be > about half of what it would be for the full bandwidth, and no > colour (as > the colour > subcarrier at 3.58 MHz is outside the pass band). You want the pass > band > of the reciever > from just below the video carrier and as high as it will go. > > /Anders > > > >________________________________
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