Tvrx and usrp_tv_rcv

GNU Radio
1

Hello All,

I’m trying to recreate Mr. Dayal’s thesis about analog tv decoding
using gnuradio.
i have already got the black and white picture after taking 8MHz band
with frequency centered in the middle of the channel.

the problem is, i got about one or two fps with my computer(2.3GHz
atlon64 x2 4400). Is this normal? what is the minimum cpu/memory
requirement for this?

thank you for your response.

–Najib.

2

On Mon, Mar 08, 2010 at 11:33:18AM +0700, Muhammad Najib wrote:

thank you for your response.
–Najib.

I’m not familiar with the code that you’re using, but in general, yes,
I would expect it to be possible to decode analog TV with your
equipment. Algorithms make a big difference…

Note also that the passband of the the TVRX is about 6 MHz wide
(NTSC), so if your channel bandwidth really is 7 or 8 MHz wide
(PAL/SECAM), you’re probably filter some of the signal.

Eric

3

Thank you for your previous response,

About the algorithm, it’s rather straight forward without
modification from the textbook

  1. for the usrp, i use decimation of 8, with tuning frekuency at the
    middle of the channel(706MHz).
    2.1 using 2 sine signal source, i shift video and audio carrier to 0Mhz.
    2.2 using sine and cosine signal source, i take the u and v signal.
  2. audio demod using wfm_rcv_pll
  3. video demod using tv_rcv+synch

in total, there are 4 sine/cosine signal generators, 5/6 filters, few
operators.

without color decoding, i’ve already got video and audio playing,
my question is which block gives the most load to the CPU?
is the additional signal generators add so much load ?

thank you for your response

4

On Wed, May 26, 2010 at 02:43:13PM +0700, Muhammad Najib wrote:

in total, there are 4 sine/cosine signal generators, 5/6 filters, few operators.

without color decoding, i’ve already got video and audio playing,
my question is which block gives the most load to the CPU?
is the additional signal generators add so much load ?

oprofile will help you figure this out.

Eric