RF output level from Foxtel Pace STU

G

Geoff C

Guest
Hi,

I am hooking up a second TV to the foxtel Pace STU via the 75 ohm RF
output. Only thing is, I'm getting 43 dBuv at the output, using a spectrum
analyser at about 618 MHz with 1 MHz resolution bandwidth. Hooking up a TV
at this output results in a noisy video signal which is obviously week. Has
anyone measured this before?
 
"Geoff C"
I am hooking up a second TV to the foxtel Pace STU via the 75 ohm RF
output. Only thing is, I'm getting 43 dBuv at the output, using a spectrum
analyser at about 618 MHz with 1 MHz resolution bandwidth.
Click to expand...

** If you want to measure the total RF signal level the bandwidth needs to
be at least 7 MHz.


Hooking up a TV
at this output results in a noisy video signal which is obviously week.
Has
anyone measured this before?
Click to expand...

** Even allowing for your bandwidth problem - that 43 dBuV level seems to
low for a noise free pic. Thermal noise in a 7 MHz bandwidth at 75 ohms is
9.5 dBuV - plus the ein of the receiver makes it more like 15dB uV. If
the RF signal is really 50 dBuV then the actual s/n is only 35 dB - ie
rather noisy - 45 dB is needed for a good pic.



.............. Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote in
news:2vd4rqF2iq5o4U1@uni-berlin.de:

"Geoff C"

I am hooking up a second TV to the foxtel Pace STU via the 75 ohm RF
output. Only thing is, I'm getting 43 dBuv at the output, using a
spectrum analyser at about 618 MHz with 1 MHz resolution bandwidth.


** If you want to measure the total RF signal level the bandwidth
needs to be at least 7 MHz.


Hooking up a TV
at this output results in a noisy video signal which is obviously
week. Has
anyone measured this before?


** Even allowing for your bandwidth problem - that 43 dBuV level
seems to low for a noise free pic. Thermal noise in a 7 MHz bandwidth
at 75 ohms is 9.5 dBuV - plus the ein of the receiver makes it more
like 15dB uV. If the RF signal is really 50 dBuV then the actual s/n
is only 35 dB - ie rather noisy - 45 dB is needed for a good pic.



............. Phil
Click to expand...
Yes, 43 dBuv is too low to expect a noise free pic. Around 60 dBuv or
more is desirable, as you point out. I tried a 5 MHz bandwidth also, and
got the same numbers as expected but this is the max this analyser can
achieve. So I am confident I am accurate within a dB or so. The unit has
been instaled for 3 weeks. I am about to ring Foxtel. BTW, the AV and
scart outputs have good signals.
 
"Geoff C"
"Phil Allison"
"Geoff C"

I am hooking up a second TV to the foxtel Pace STU via the 75 ohm RF
output. Only thing is, I'm getting 43 dBuv at the output, using a
spectrum analyser at about 618 MHz with 1 MHz resolution bandwidth.


** If you want to measure the total RF signal level the bandwidth
needs to be at least 7 MHz.


Hooking up a TV
at this output results in a noisy video signal which is obviously
week. Has
anyone measured this before?


** Even allowing for your bandwidth problem - that 43 dBuV level
seems to low for a noise free pic. Thermal noise in a 7 MHz bandwidth
at 75 ohms is 9.5 dBuV - plus the ein of the receiver makes it more
like 15dB uV. If the RF signal is really 50 dBuV then the actual s/n
is only 35 dB - ie rather noisy - 45 dB is needed for a good pic.


Yes, 43 dBuv is too low to expect a noise free pic. Around 60 dBuv or
more is desirable, as you point out. I tried a 5 MHz bandwidth also, and
got the same numbers as expected but this is the max this analyser can
achieve. So I am confident I am accurate within a dB or so.
Click to expand...

** Yeah - on reflection, the energy in a TV pic signal is not evenly
spread across the bandwidth, so as long as your analyser is reading the
vision carrier level OK in a 1MHz bandwidth that figure will be within 3 dB.

If the video signals are AOK as you say - then the RF modulator in the
box itself must be crook.



............. Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote in
news:2vd7g6F2kd8s3U1@uni-berlin.de:

"Geoff C"
"Phil Allison"
"Geoff C"

I am hooking up a second TV to the foxtel Pace STU via the 75 ohm
RF output. Only thing is, I'm getting 43 dBuv at the output, using
a spectrum analyser at about 618 MHz with 1 MHz resolution
bandwidth.


** If you want to measure the total RF signal level the bandwidth
needs to be at least 7 MHz.


Hooking up a TV
at this output results in a noisy video signal which is obviously
week. Has
anyone measured this before?


** Even allowing for your bandwidth problem - that 43 dBuV level
seems to low for a noise free pic. Thermal noise in a 7 MHz
bandwidth at 75 ohms is 9.5 dBuV - plus the ein of the receiver
makes it more like 15dB uV. If the RF signal is really 50 dBuV then
the actual s/n is only 35 dB - ie rather noisy - 45 dB is
needed for a good pic.


Yes, 43 dBuv is too low to expect a noise free pic. Around 60 dBuv or
more is desirable, as you point out. I tried a 5 MHz bandwidth also,
and got the same numbers as expected but this is the max this
analyser can achieve. So I am confident I am accurate within a dB or
so.


** Yeah - on reflection, the energy in a TV pic signal is not
evenly spread across the bandwidth, so as long as your analyser is
reading the vision carrier level OK in a 1MHz bandwidth that figure
will be within 3 dB.

If the video signals are AOK as you say - then the RF modulator in
the
box itself must be crook.



............ Phil
Click to expand...
Well I rang Foxtel, they say there probably is something wrong with the
box. I spoke with a technical guy, he knew what a dB was so that was
satisfying! However, their terms and conditions only warranty 1 TV
connections. So I have to hookup the main TV to the RF output as if that is
my primary connection! So I have to be deceitful to get it fixed.
 
"Geoff C" <notinterestedin@spa.comm> wrote in message
news:V_dkd.1162$ob1.6247@nasal.pacific.net.au...
"Phil Allison" <philallison@tpg.com.au> wrote in
news:2vd7g6F2kd8s3U1@uni-berlin.de:


"Geoff C"
"Phil Allison"
"Geoff C"

I am hooking up a second TV to the foxtel Pace STU via the 75 ohm
RF output. Only thing is, I'm getting 43 dBuv at the output, using
a spectrum analyser at about 618 MHz with 1 MHz resolution
bandwidth.


** If you want to measure the total RF signal level the bandwidth
needs to be at least 7 MHz.


Hooking up a TV
at this output results in a noisy video signal which is obviously
week. Has
anyone measured this before?


** Even allowing for your bandwidth problem - that 43 dBuV level
seems to low for a noise free pic. Thermal noise in a 7 MHz
bandwidth at 75 ohms is 9.5 dBuV - plus the ein of the receiver
makes it more like 15dB uV. If the RF signal is really 50 dBuV then
the actual s/n is only 35 dB - ie rather noisy - 45 dB is
needed for a good pic.


Yes, 43 dBuv is too low to expect a noise free pic. Around 60 dBuv or
more is desirable, as you point out. I tried a 5 MHz bandwidth also,
and got the same numbers as expected but this is the max this
analyser can achieve. So I am confident I am accurate within a dB or
so.


** Yeah - on reflection, the energy in a TV pic signal is not
evenly spread across the bandwidth, so as long as your analyser is
reading the vision carrier level OK in a 1MHz bandwidth that figure
will be within 3 dB.

If the video signals are AOK as you say - then the RF modulator in
the
box itself must be crook.



............ Phil




Well I rang Foxtel, they say there probably is something wrong with the
box. I spoke with a technical guy, he knew what a dB was so that was
satisfying! However, their terms and conditions only warranty 1 TV
connections. So I have to hookup the main TV to the RF output as if that
is
my primary connection! So I have to be deceitful to get it fixed.
Click to expand...
I know a girl who works for Foxtel customer support, which suprised me
because she had not previously shown any interest in technical matters. I
asked her what she does. Apparently a regular part of it was asking
customers to check the polarisation settings of their LNB. I asked her what
a LNB is. She had absolutely no idea what a LNB is and still has none to
this day. Moral of the Story - They might talk the jargon but they
comprehend nothing. Good luck.
John

John Smyth
 
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