DIYbanter - View Single Post - Audio Precision System One Dual Domani Measuirement Systems

Terry Casey

In article ,
says...

In message , Arny Krueger
writes

"Terry Casey" wrote in message
...

A couple of questions regarding that list:

Why is the HRC channel spacing offset[1] by 300Hz - 6.0003MHz instead of
6MHz?

I don't know.

I recall once specially tweaking a UK 8MHz HRC harmonic comb generator
(to which all of the TV channels were locked). It was a little above (or
was it below?) 8MHz. There was a reason for this, but at the moment, I
can't remember what it was.

One system where this was done was the old BT Westminster system -
probably very useful in an area where I would expect a lot of off-air
reception problems.

I don't know what offset they used but, as an example, if you alter the
comb to 7.990963855MHz, channel E45 is bang on (663.25MHz) so, if you
centred the five off-airs around this using E41, E43, E45, E47 and E49,
the worst case error will be +/-36kHz from the nominal frequency.

--

Terry