Comparing DTV tuner cards (PCI) tuner sensitivity

On Sep 20, 12:31 pm, G-squared wrote:
On Sep 20, 7:43 am, "Mr. Land" wrote:
snip
Without knowing his location, channel number of the DTV and power
level of the DTVs in his area, there is no way to make any kind
of
evaluation. A fellow video engineer I work with has the Hauppage
1600
and a 950 USB tuner and both work well. I have 3 ATI HDTV Wonder
cards
and they have 'normal' sensitivity. The comparison tuner is a
Samsung
SIR-T165.

GG

What is "normal" sensitivity? In terms of a dBm value?

Here are 2 photos of my antenna into a Tektronix 2712 spectrum
analyzer. Does this help? I have all the LA DTV pix

http://www.flickr.com/photos/[email protected]/1333953816/

GG

Wish I had one of those! Not sure I understand what this is showing -
does this depict the strength of the signal coming from your antenna
plotted against a range of frequencies? I see "-50 dBm" on the
readout,
how does that relate to the display? I'm guessing it's some kind of
average, i.e. the scope is showing that on average you're getting
-50 dBm out of your antenna. How far off is that guess?

Let me take a WAG at how you intended me to interpret this - if this
plot shows a healthy signal of -50dBm across the band of interest, any
tuner with "normal" sensitivity shouldn't require more than that?

Thanks a lot for the reply.

On Sep 20, 12:36 pm, "jolt" wrote:
"Mr. Land" wrote in message

oups.com...



On Sep 19, 3:40 pm, "jolt" wrote:
"Mr. Land" wrote in message

oups.com...

Hi,

Based on some excellent answers to my first noob question in this
group, I bought a PCI DTV tuner card (Hauppauge WinTV-PVR-1600). My
main requirements we includes hardware-based MPEG2 encoding, ATSC-
capable, and PCI (not PCIe) interface.

But the tuner sensitivity in this card seems pretty bad. Case in
point: using rabbit ears having 300 ohm twinlead with a 75-ohn balun
on the end - an $80 10 inch television can tune and display a fringe
channel in my area (somewhat snowy, but watchable), while the
Hauppauge cannot (behaves as if there's no signal at all).

I've searched the Hauppauge site for technical specs in an attempt to
find this card's rated tuner sensitivity (i.e. minimum RF signal
strength required, for instance -75dBm) but can't find that.

Are there any sites which would have ratings like these for these
products? This seems like an important buying decision point,
especially for ATSC (OTA) tuners. If the Hauppauge doesn't measure up
to other brands with respect to this specification, it's going back to
the store.

Thanks for any help!

Are you comparing the two using the same antenna are using the sets
antenna
vs. an indoor antenna.

I am comparing the two with exactly the same antenna with exactly the
same orientation
(i.e. I am not moving the antenna at all, merely unplugging it from
the little TV then
plugging into the card's RF input.)

On the portable your likely tuning for a NTSC signal
which will be VHF and the ATSC channels are for the most part UHF. Are
you
comparing ATSC i.e. digital to NTSC analog, sorry it's a little confusing
because you don't state which tuner you are checking the strength for.

This particular model card is what they call a "Hybrid" - it actually
has two
tuners in it: a traditional analog VHF/UHF tuner, and a separate ATSC
tuner. Each
tuner has its own RF input (each has a standard "F" antenna input
connector.)

My comparison consisted of plugging the antenna into the small TV's
antenna
input connector, then removing it and plugging it into the RF input
for the
card's analog tuner. Again, while the little TV was able to give me a
fairly
decent picture, the card didn't even detect that channel. I know the
card
isn't defective, because if I give it a strong enough signal, it will
work.

I live in a fringe area, which is why I'm concerned with the RF input
sensitivity of the card's tuners.

I've got a 1600 and the ATSC tuner seem to tune as well as other similar
tuners the NTSC is hooked to cable so haven't tried an antenna for
tuning.
It is possible the tuners will require more signal strength then your
portable TV set dependent somewhat on how the software reacts to low
signal
strength

Hmm, I don't see how software's going to effect the tuner
sensitivity. Isn't that
more of a function of the design/quality of the first stage RF
amplifier inside
the tuners? I.e. wouldn't it be a function of the hardware design?
Unless they've
designed it such that the software can control the gain of the RF
stages, but
I kind of doubt they're that sophisticated.

Thanks for your reply.

While allowing a television's NTSC tuner to function with a poor signal has
no draw backs aside from poor picture quality, a PC tuner requires a solid
signal so that during the process of converting the signal to a PEG file
that it doesn't lock the system with errors. Software differs in what is
considered a safe level to allow the software to display that the tuner see
a signal. Good signal strength helps avoid phantom type problems, recording
errors or system lockups. I've seen older style tuners that don't have an
PEG encoder be much more flexible.

I see, so the tuner may have below-par sensitivity by design. Thank
you.

And you're testing with rabbit ears? That doesn't really make a hell of a
lot of sense.

Sure it does. Rabbit ears are going to give me very low RF levels -
short
of having an RF antennuator, they're a fast and easy way to see how a
tuner
performs under less-than-ideal conditions.

I don't know about analog because I don't even have any tuners that work
with NTSC. Mine are all first generation ATSC circa 2002. I originally
bought the latest greatest (5th gen tuner at the time) at the latest
greatest price too I might add. After comparing to the old ones I could
get for under $20 now, I sold the expensive one. When you can buy 6 of
them for what the 1 expensive one cost... Anyway, for ATSC, The software
application does control the sensitivity of the card for ATSC lock.

But that's not the same as controlling the RF gain of the tuner's
input stages,
like an AGC circuit. That sounds like "what level of signal am I
going to require
before I will attempt to decode the digital stream" vs "what gain do I
want
the early stage RF amplifiers to have inside the tuner".

With the software I use, you can set the timeout to wait for a lock, and the
signal strength needed to be considered a lockable station. The default
wasn't long enough for a couple of weak stations around here. Does all
software give you those options? Couldn't say. MythTV does. Key to any
ATSC reception is the antenna. I'm about 42 miles from the towers and with
my old uhf/vhf combo antenna I couldn't get one or two of the UHF ATSC
stations (NTSC uhf had always been flacky too) until I added a decent UHF
antenna.

That's interesting. I've been using an old VHF/UHF antenna for our
plasma,
and I thought it was doing just fine - perhaps it'd be worthwhile to
try a
dedicated UHF antenna. Thanks for this information.

Rabbit ears is about useless here.
I'm still using the old
antenna for vhf although it really needs to be replaced too, but works
well with the one ATSC station on VHF here. So if you're really in a
fringe area, rabbit ears just isn't going to cut it. Worry more about your
antenna than the tuner. I suspect any PC tuner will work well with the
proper antenna for the location. I know the old cheap ones I use do.

I guess I've been laboring under the assumption that, given a decent
antenna
(NOT rabbit ears!), a tuner with better RF sensitivity will be able
to,
on average, obtain more channels at a sufficient enough signal for
decoding
than one with less sensitivity. I.e. if my given antenna delivers -60
dBm of
signal for channel 2.1 and -40 dBm of signal for channel 7.1, and I
hook it
up to ATSC tuner "A" that has -50 dBm RF sensitivity, then I switch to
ATSC tuner "B" with -75 dBm sensitivity, with tuner "A" I'll only be
able
to watch channel 7.1, but with "B" I'll get both channels. Does this
not
make sense?


Thanks for taking the time to reply.

On Sep 20, 12:37 am, G-squared wrote:
On Sep 20, 12:16 am, wrote:
On Sep 19, 1:00 pm, G-squared wrote:

snip
Without knowing his location, channel number of the DTV and power
level of the DTVs in his area, there is no way to make any kind
of
evaluation. A fellow video engineer I work with has the Hauppage
1600
and a 950 USB tuner and both work well. I have 3 ATI HDTV Wonder
cards
and they have 'normal' sensitivity. The comparison tuner is a
Samsung
SIR-T165.

GG

This first comment isn't for the first party rather it is something
of
a
half baked idea. Perhaps a standalone tuner somehow hooked
to computer would be the way to go. Direct to a computer
monitor it would surely work. Though I'd want to be about to record
on HD for time shifting. I know this is half baked but is it
possible?
I suppose I'd still need software even if someone got it hooked up
or
set
up correctly. I'd think (without real basis) a standalone tuner
would
likely be
better engineered and hence better better at picking up a signal.
Samsung makes one and there are others some .

I'd think the first party should consider a UHF antenna.

The problems with recording DTV is the data rate. While MPEG2 is not
overly high at 19.3 megabits/second, getting that stream into the
computer from an external tuner is a big chore. The tuner _could_ have
a firewire port which is easiest but more likely what comes out is
component analog or DVI / HDMI. Component analog need to be converted
back to digital - at 1.5 GIGABIT/second (550 gigabyte/hour). This is a
BIG deal to work with. The internal tuners simply hand over the MPEG2
stream at 20 megabits (75 times less data than your own converter).
DVI / HDMI is already digital but need to be handled at full data rate
so needs to be re-converted to MPEG 2 or 4. Bottom line - sell the
tuner on eBay to someone who needs it and get a computer tuner - PCI
or USB. FAR less aggravation and better results.

As far as better engineered - who can tell? Will it last a few years?
Is it sensitive anough? My first ATI tuner is 34 months old and doing
fine. Performance is reliable at this point. The other 2 ATIs were
from eBay so I don't know the total age, just that they've been here
for over a year and also doing fine.

GG

Thank you very much.

I'll wait a year and then when I replace my computer
system an inner DTV card will be part on the new system.
Mr Bills "new" operating system was enough to make me defer
on getting a new computer system.

I recently got a little HTV for personal use. Apparently I am
41 or 42 miles from the stations, the over-the-air digital signals
are coming in better than the old analog signals.
The digital signal from the public station does have some
faults that I assume lays in the system. I get this stop
action effect that reminds me of an old Realplayer video when
one could still get content for it by way of dialup.
A fault in compression or decompression????

On Sep 24, 4:58 am, wrote:
On Sep 20, 12:37 am, G-squared wrote:



On Sep 20, 12:16 am, wrote:
On Sep 19, 1:00 pm, G-squared wrote:

snip
Without knowing his location, channel number of the DTV and power
level of the DTVs in his area, there is no way to make any kind
of
evaluation. A fellow video engineer I work with has the Hauppage
1600
and a 950 USB tuner and both work well. I have 3 ATI HDTV Wonder
cards
and they have 'normal' sensitivity. The comparison tuner is a
Samsung
SIR-T165.

GG

This first comment isn't for the first party rather it is something
of
a
half baked idea. Perhaps a standalone tuner somehow hooked
to computer would be the way to go. Direct to a computer
monitor it would surely work. Though I'd want to be about to record
on HD for time shifting. I know this is half baked but is it
possible?
I suppose I'd still need software even if someone got it hooked up
or
set
up correctly. I'd think (without real basis) a standalone tuner
would
likely be
better engineered and hence better better at picking up a signal.
Samsung makes one and there are others some .

I'd think the first party should consider a UHF antenna.

The problems with recording DTV is the data rate. While MPEG2 is not
overly high at 19.3 megabits/second, getting that stream into the
computer from an external tuner is a big chore. The tuner _could_ have
a firewire port which is easiest but more likely what comes out is
component analog or DVI / HDMI. Component analog need to be converted
back to digital - at 1.5 GIGABIT/second (550 gigabyte/hour). This is a
BIG deal to work with. The internal tuners simply hand over the MPEG2
stream at 20 megabits (75 times less data than your own converter).
DVI / HDMI is already digital but need to be handled at full data rate
so needs to be re-converted to MPEG 2 or 4. Bottom line - sell the
tuner on eBay to someone who needs it and get a computer tuner - PCI
or USB. FAR less aggravation and better results.

As far as better engineered - who can tell? Will it last a few years?
Is it sensitive anough? My first ATI tuner is 34 months old and doing
fine. Performance is reliable at this point. The other 2 ATIs were
from eBay so I don't know the total age, just that they've been here
for over a year and also doing fine.

GG

Thank you very much.

I'll wait a year and then when I replace my computer
system an inner DTV card will be part on the new system.
Mr Bills "new" operating system was enough to make me defer
on getting a new computer system.

I recently got a little HTV for personal use. Apparently I am
41 or 42 miles from the stations, the over-the-air digital signals
are coming in better than the old analog signals.
The digital signal from the public station does have some
faults that I assume lays in the system. I get this stop
action effect that reminds me of an old Realplayer video when
one could still get content for it by way of dialup.
A fault in compression or decompression????


I'm surprised no has mentioned this:
http://www.blackmagic-design.com/products/intensity/
and the Pro version as well, for capturing HD content on your PC.

As for the digital tuner, I bought one of the air2pc cards off Ebay.
I'm happy with it, and much easier than the analog tuner card coupled
with the voom box (for the digital tuner) that I was using before that.

On Wed, 19 Sep 2007 09:37:42 -0700, "Mr. Land"
wrote:

Hi,

Based on some excellent answers to my first noob question in this
group, I bought a PCI DTV tuner card (Hauppauge WinTV-PVR-1600). My
main requirements we includes hardware-based MPEG2 encoding, ATSC-
capable, and PCI (not PCIe) interface.

But the tuner sensitivity in this card seems pretty bad. Case in
point: using rabbit ears having 300 ohm twinlead with a 75-ohn balun
on the end - an $80 10 inch television can tune and display a fringe
channel in my area (somewhat snowy, but watchable), while the
Hauppauge cannot (behaves as if there's no signal at all).

I've searched the Hauppauge site for technical specs in an attempt to
find this card's rated tuner sensitivity (i.e. minimum RF signal
strength required, for instance -75dBm) but can't find that.

Are there any sites which would have ratings like these for these
products? This seems like an important buying decision point,
especially for ATSC (OTA) tuners. If the Hauppauge doesn't measure up
to other brands with respect to this specification, it's going back to
the store.

Thanks for any help!


I just wanted to throw in my 2 cents here. I am assuming that you
are using the NTSC input on the 1600 since you mention you're trying
to get the same channel that is snowy on your small TV. From previous
experience with Hauppauge products I would say that you cannot use the
NTSC tuner on the card as an example of how the ATSC tuner will
perform. I have used Happauge NTSC/ATSC cards in the past with
excellent ATSC tuners and really lousy NTSC ones. You really need to
compare apples and apples here. See if someone you know can loan you
a quality ATSC STB and compare the reception on it to the ATSC tuner
on the 1600.

DSF