My new/old Technics tuner advises me my FM signal strength is 52 dB - is
that good, bad or just plain ugly, given the palaver with the aerial
installation a while back?

TIA

(Also posted to the vinyl group in error!)

"Keith G" wrote in message
...

My new/old Technics tuner advises me my FM signal strength is 52 dB - is
that good, bad or just plain ugly, given the palaver with the aerial
installation a while back?

TIA

(Also posted to the vinyl group in error!)
Keith,

Without knowing what the 0dB reference is, it's difficult to know *what*
they mean.

If the signal strength is -52dBm into 75 ohms, then that's a voltage level
of 687uV which is a bit low. Knowing where you're located and how far from
Peterborough, I would have expected some 2mV at the tuner, but maybe you
have some high ground between you and the TX. If the tuner doesn't hiss on
Radio 3 in the evenings when the processing is turned off, then you should
be OK even on the signal you have. Most tuners achieve 50dB S/N ratio with
under 100uV, but don't reach their maximum S/N ratio until nearer 1mV.

S.

"Serge Auckland" wrote in message
...

"Keith G" wrote in message
...

My new/old Technics tuner advises me my FM signal strength is 52 dB - is
that good, bad or just plain ugly, given the palaver with the aerial
installation a while back?

TIA

(Also posted to the vinyl group in error!)
Keith,

Without knowing what the 0dB reference is, it's difficult to know *what*
they mean.


I never know what they mean!! :-)



If the signal strength is -52dBm into 75 ohms, then that's a voltage level
of 687uV which is a bit low. Knowing where you're located and how far from
Peterborough, I would have expected some 2mV at the tuner, but maybe you
have some high ground between you and the TX. If the tuner doesn't hiss on
Radio 3 in the evenings when the processing is turned off, then you should
be OK even on the signal you have. Most tuners achieve 50dB S/N ratio with
under 100uV, but don't reach their maximum S/N ratio until nearer 1mV.


OK Serge, thanks for that

Ordinarily, the signal/sound quality seems to be very good. I have only
noticed a bit of R3 hiss on the odd occasion in the evenings.....

On Thu, 27 Apr 2006 13:44:00 +0100, "Serge Auckland"
wrote:

If the signal strength is -52dBm into 75 ohms, then that's a voltage level
of 687uV which is a bit low.

My Sony ST-S311 tuner gives the signal strength in dBf, which I
believe is relative to one femtowatt (10E-15W). If my calculations are
correct, then 52dBf would equate to 109uV, which is not very good at
all.

The OP's manual should hopefully define the measurement units used.

--
Chris Isbell
Southampton, UK

one femtowatt (10E-15W).

No. 1E-15 W.

10E-15 W == 1E-14 W == 10^-14 W.

1 fW = 10^-15 W


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

On Thu, 27 Apr 2006 18:54:28 +0100, "Fleetie"
wrote:

one femtowatt (10E-15W).

No. 1E-15 W.


Correct. I meant 10^-15W, which is, as you say, 1E-15.

To err is human....

--
Chris Isbell
Southampton, UK

On Thu, 27 Apr 2006 17:49:12 +0100, Chris Isbell
wrote:

On Thu, 27 Apr 2006 13:44:00 +0100, "Serge Auckland"
wrote:

If the signal strength is -52dBm into 75 ohms, then that's a voltage level
of 687uV which is a bit low.

My Sony ST-S311 tuner gives the signal strength in dBf, which I
believe is relative to one femtowatt (10E-15W). If my calculations are
correct, then 52dBf would equate to 109uV, which is not very good at
all.

The OP's manual should hopefully define the measurement units used.

The trouble here of course is that Keith is obsessed with
measurements. What really matters is how the signal *sounds*! Is it
clean, with no multipath distortion and no noticeable hiss? Then you
have enough signal strength. :-)

--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 28 Apr 2006 06:32:16 +0100, Stewart Pinkerton
wrote:

The trouble here of course is that Keith is obsessed with
measurements. What really matters is how the signal *sounds*! Is it
clean, with no multipath distortion and no noticeable hiss? Then you
have enough signal strength. :-)

Yes, up to a point.

I noticed a matterable improvement going from an adequate to a very
good aerial signal. This observation was not validated using a
double-blind level matched test, so it may be a consequence of the
effort expended optimising the aerial, or possibly down to reducing
multipath. ;-)

It would be interesting to hear from those who know about RF whether
there might be an engineering basis for this observation.

--
Chris Isbell
Southampton, UK

"Chris Isbell" wrote in message
...
On Fri, 28 Apr 2006 06:32:16 +0100, Stewart Pinkerton
wrote:

The trouble here of course is that Keith is obsessed with
measurements. What really matters is how the signal *sounds*! Is it
clean, with no multipath distortion and no noticeable hiss? Then you
have enough signal strength. :-)

Yes, up to a point.

I noticed a matterable improvement going from an adequate to a very
good aerial signal. This observation was not validated using a
double-blind level matched test, so it may be a consequence of the
effort expended optimising the aerial, or possibly down to reducing
multipath. ;-)

It would be interesting to hear from those who know about RF whether
there might be an engineering basis for this observation.

--
Chris Isbell
Southampton, UK

An "adequate" signal presumably is one that produces a pleasing result, that
is, an adequate S/N ratio and low impulsive interference due to the receiver
going well into limiting. With a "very good" signal, the S/N ration will
reach the receiver's maximum, which could be 10-15dB better than previously
achieved with an "adequate" signal. Also, the receiver will be much further
into limiting, and consequently impulsive interference will be reduced
further still. These will produce a feeling that the reception is a lot
better than before, as noise will be considerably lower, and the reception
will feel more "stable" due to lower impulsive interference. If you had
carried out measurements before and after, you could have quantified these
impressions, but nevertheless, there is a sound engineering reason for the
improvements you noticed subjectively.

S.

"Stewart Pinkerton" wrote in message
...
On Thu, 27 Apr 2006 17:49:12 +0100, Chris Isbell
wrote:

On Thu, 27 Apr 2006 13:44:00 +0100, "Serge Auckland"
wrote:

If the signal strength is -52dBm into 75 ohms, then that's a voltage
level
of 687uV which is a bit low.

My Sony ST-S311 tuner gives the signal strength in dBf, which I
believe is relative to one femtowatt (10E-15W). If my calculations are
correct, then 52dBf would equate to 109uV, which is not very good at
all.

The OP's manual should hopefully define the measurement units used.

The trouble here of course is that Keith is obsessed with
measurements. What really matters is how the signal *sounds*! Is it
clean, with no multipath distortion and no noticeable hiss? Then you
have enough signal strength. :-)



You couldn't be more wrong - I almost *never* measure anything and only go
'by ear' in the final analysis. The only reason I asked is that I discovered
if you hold the Mode switch (Stereo/Mono) down for a few seconds it displays
the 'signal strength' and, no, before anybody points it out - I don't
trust/believe it is necessarily anything like accurate or meaningful.

The tuner sounds fine, the numbers are academic (it only reads 50 dB this
morning)....