[BC] AM Protection

[Barry McLarnon]

On Saturday 02 July 2005 12:45, DANA PUOPOLO wrote:
> Ironic huh?
>
> We protect other countries' AM stations, yet could care less about doing
> the same to our own.
>
> Thanks, IBOC!

While it's true that current protection rules leave domestic stations more 
or less defenceless against IBOC interference, it's not necessarily the 
case that foreign stations get better protection.  In fact, in some 
important respects, the situation is worse for other countries.

Roy Stype wrote:
>None of these international agreements require nighttime skywave 
>protection to foreign strations operating on first adjacent channels, 
>which is only a requirement of the U.S.'s domestic AM protection 
>criteria. 

Skywave interference from first adjacent IBOC stations is THE big problem 
with nighttime AM IBOC operation.  As Roy points out, foreign stations get 
no protection whatever from this, despite the fact that the IBOC stations 
in question are dumping *co-channel* digital noise on them.  And those 
digital signals cause more audible interference (6-7 dB more) than a 
co-channel AM signal having the same transmitted power.  If the primary 
IBOC sidebands were properly co-ordinated as the distinct entities that 
they are, then there would be some protection from them.  But that won't 
happen, since it would stop the IBOC train dead in its tracks.  I don't 
think anyone seriously believes that nighttime operation won't get the FCC 
go-ahead sometime later this year.

Not only does the hybrid IBOC system contravene the aforementioned 
international agreements, but it's downright un-neighborly, dontcha think?

Barry

-- 
Barry McLarnon VE3JF  Ottawa, ON