Signal strength and signal quality, what does it mean?

Can the group help please?

Being new to Freeview, and looking at the menu on my Sony Freeview box, I
understand what the 'signal strength means, but, not too sure what is meant
by 'signal quality!'

Can someone explain please?

Brian (Huddersfield, West Yorkshire)

"Horse.trader" wrote in message
...
Can the group help please?

Being new to Freeview, and looking at the menu on my Sony Freeview box, I
understand what the 'signal strength means, but, not too sure what is
meant by 'signal quality!'

Can someone explain please?

It's an assessment of the extent to which the receiver is able to decode the
data stream. If the data stream is a bit garbled due to the signal taking
several paths or due to interference the decoding errors will increase.

Bill

"Bill Wright" wrote in message
...

"Horse.trader" wrote in message
...
Can the group help please?

Being new to Freeview, and looking at the menu on my Sony Freeview box, I
understand what the 'signal strength means, but, not too sure what is
meant by 'signal quality!'

Can someone explain please?

It's an assessment of the extent to which the receiver is able to decode
the data stream. If the data stream is a bit garbled due to the signal
taking several paths or due to interference the decoding errors will
increase.

Bill
Thanks Bill...............

Makes sense now!

Brian

Bill Wright wrote:
"Horse.trader" wrote in message
...
Can the group help please?

Being new to Freeview, and looking at the menu on my Sony Freeview
box, I understand what the 'signal strength means, but, not too sure
what is meant by 'signal quality!'

Can someone explain please?

It's an assessment of the extent to which the receiver is able to
decode the data stream. If the data stream is a bit garbled due to
the signal taking several paths or due to interference the decoding
errors will increase.

Though might be more use if the box could assess the programme content and
switch off the quiz channels automatically due to low signal quality :-)



--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

"Horse.trader" wrote in message
news

"Bill Wright" wrote in message
...

"Horse.trader" wrote in message
...
Can the group help please?

Being new to Freeview, and looking at the menu on my Sony Freeview box,
I understand what the 'signal strength means, but, not too sure what is
meant by 'signal quality!'

Can someone explain please?

It's an assessment of the extent to which the receiver is able to decode
the data stream. If the data stream is a bit garbled due to the signal
taking several paths or due to interference the decoding errors will
increase.

Bill
Thanks Bill...............

Makes sense now!

The reason it is shown separately to signal strength is that there is no
direct infallible relationship between the two. Certainly, if the signal
strength drops to the point where the receiver's own RF noise becomes an
issue then there will be a relationship. But if the signal has already been
amplified (by a masthead amp or a distribution system) it could appear at
the receiver at a high strength, but already degraded in 'quality' by the
noise from the amplifier. There's also the question of interference. It's
quite interesting to observe the BER (Bit Error Rate or Ratio) degrade if
there's another signal on the same channel. The 'strength' reading will most
likely remain unchanged.

Some time ago I went out to a tenant who was complaining bitterly about the
TV distribution system. Without telling the story in dribs and drabs, the
way it was revealled to me, but telling it as it happened, he had bought a
Freeview box and obtained zero results. Having exchanged the box (by
bluster) he had tried the new one with the same result. He then went into
the loft and connected a length of B & Q's best coax to the tap-off unit. He
had also decided to put the TV at the other side of the living room, so the
cable snaked elegantly down the stairs. And he had simply connected it
across the trunk terminals. His house was only the second in the row and the
tap value was 35dB. The system is in good working order and the analogue
signal level on the trunk at that point is about 50dBmV. He had about 40dBmV
(analogue), 20dBmV (digi) available to the Freeview box, which then showed
max quantity and min quality. The box had severe indigestion in other words.
At this point he complained to the council. I removed the new cable, and
tested the signal at his outlet. Finding that it was very poor I replaced
the outlet plate, giving the box an input of plus and minus ten (d and a
respectively).

Bill

In message , Bill Wright
writes
"Horse.trader" wrote in message
...
Can the group help please?

Being new to Freeview, and looking at the menu on my Sony Freeview box,
I understand what the 'signal strength means, but, not too sure what is
meant by 'signal quality!'

Can someone explain please?

It's an assessment of the extent to which the receiver is able to decode
the data stream. If the data stream is a bit garbled due to the signal
taking several paths or due to interference the decoding errors will
increase.

Bill
Thanks Bill...............

Makes sense now!

The reason it is shown separately to signal strength is that there is no
direct infallible relationship between the two. Certainly, if the signal
strength drops to the point where the receiver's own RF noise becomes an
issue then there will be a relationship. But if the signal has already been
amplified (by a masthead amp or a distribution system) it could appear at
the receiver at a high strength, but already degraded in 'quality' by the
noise from the amplifier. There's also the question of interference. It's
quite interesting to observe the BER (Bit Error Rate or Ratio) degrade if
there's another signal on the same channel. The 'strength' reading will most
likely remain unchanged.

Some time ago I went out to a tenant who was complaining bitterly about the
TV distribution system. Without telling the story in dribs and drabs, the
way it was revealled to me, but telling it as it happened, he had bought a
Freeview box and obtained zero results. Having exchanged the box (by
bluster) he had tried the new one with the same result. He then went into
the loft and connected a length of B & Q's best coax to the tap-off unit. He
had also decided to put the TV at the other side of the living room, so the
cable snaked elegantly down the stairs. And he had simply connected it
across the trunk terminals. His house was only the second in the row and the
tap value was 35dB. The system is in good working order and the analogue
signal level on the trunk at that point is about 50dBmV. He had about 40dBmV
(analogue), 20dBmV (digi) available to the Freeview box, which then showed
max quantity and min quality. The box had severe indigestion in other words.
At this point he complained to the council. I removed the new cable, and
tested the signal at his outlet. Finding that it was very poor I replaced
the outlet plate, giving the box an input of plus and minus ten (d and a
respectively).

Bill


On my iDTV, signal strength ranges from zero to almost zero, while
quality shows as excellent.

The picture is fine 99% of the time, as long as the clapped out VW
outside isn't coming or going.

It's been like this for a few weeks, in line with others posting here
about weaker signals.

If I switch on the amp which I use for the PC lead, signal strength goes
to around 60.

How can I get anything with zero signal strength?
--
Ian

Ian wrote:
On my iDTV, signal strength ranges from zero to almost zero, while
quality shows as excellent.

The picture is fine 99% of the time, as long as the clapped out VW
outside isn't coming or going.

It's been like this for a few weeks, in line with others posting here
about weaker signals.

If I switch on the amp which I use for the PC lead, signal strength
goes to around 60.

How can I get anything with zero signal strength?

Well, clearly it isn't zero! Blame the programmers. Possibly the signal
strength has fallen below some threshold which has been arbitrarily declared
the weakest useable signal. It might be that for tuning purposes such muxes
would be ignored, but having once acquired them, you are still able to use
them.

In article , Bill Wright
wrote:


The reason it is shown separately to signal strength is that there is no
direct infallible relationship between the two. Certainly, if the
signal strength drops to the point where the receiver's own RF noise
becomes an issue then there will be a relationship. But if the signal
has already been amplified (by a masthead amp or a distribution system)
it could appear at the receiver at a high strength, but already
degraded in 'quality' by the noise from the amplifier. There's also the
question of interference. It's quite interesting to observe the BER
(Bit Error Rate or Ratio) degrade if there's another signal on the same
channel. The 'strength' reading will most likely remain unchanged.

My other half last week decided to employ her usual tactic when something
doesn't work.

A) press buttons at random

B) then complain to me and demand I 'fix it'

In this case it was the TV and I found that our Nokia 221T was displaying
interesting channel/mux data, including a C/N ratio in dB and a signal
level in dBm. (Not dBmV or dBmicroV.)

Investigating I found this was produced by 'navi' then 'opt'. Useful
discovery.

However the relevance here is that when I checked I found that the signal
levels reported varied over nearly a 20dB range from one MUX to another,
but the C/N ratios were all in a range from 23-25 dB... Not sure which
values I now put least confidence in taking literally. ;-)

All the MUXs were said to give error rates of '0e0'. I guess that means
'low'... ;-

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article ,
Ian wrote:
How can I get anything with zero signal strength?

The signal strength will be measured on a logarithmic scale, and on
such a scale "zero" is just an arbitrary point. You can perfectly
well have negative strengths. Probably they just set zero to be some
arbitrary "very low" level, and don't show anything less than that.

-- Richard