[opendtv] Re: CH 6 Gets FCC STA to increase power

You have to be very careful trying to determine S/N ratio with
a spectrum analyzer. There are many correction factors involved.

I've posted spectrum analyzer pics of the SF Bay Area stations
on AVSForum.

http://www.avsforum.com/avs-vb/showthread.php?p=16688005#post16688005

On channel 12 (KNTV-DT), the anaylzer shows 40 dB of S/N, but the real
S/N measured with attenuators is closer to 65 dB.

Also, to address Tom's question about multipath, check the huge amount
of multipath on channel 36 (attatched). This signal gives earlier generation
tuners a lot of problems (sometimes not locking at all), but is received 100% 
error free with a 6th gen AMD/ATI T316 chip.

Ron

Albert Manfredi wrote:


Cliff Benham wrote:


CH 6 WPVI-DT announced on the 6AM news that the
FCC granted them an STA to increase power. Here is
a spectrum analyzer pic which indicates about a 10
dB higher level than previously available.


And not quite 15 dB of C/N, especially in the higher parts of the channel. On 
my Accurian's signal monitor, it is really obvious how the signal becomes solid 
if the C/N can stay just a fraction above 15 dB.

According to the FCC's table, WPVI was at 74.1 KW in analog. So 8.56 KW does 
actually exceed the 12 dB rule of thumb. It's only 9.4 dB less than the analog 
signal.

They have applied for 30.2 KW. Is that what they're transmitting now, you 
think? The RF noise down there probably has a lot to do with the problem.

Bert

JPEG image

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