[BC] Re: IBOC secrets and my opinion

[Barry McLarnon]

On Tuesday 27 March 2007 20:27, WFIFeng at aol.com wrote:
> The issue is what the skywave IBUZ signal is going to do when it plasters,
> *on-channel* , the *local* stations' signals!

Agreed, but...

> 50Kw station on 1000 with IBUZ is transmitting 500 watts (average) of white
> noise on 990 and on 1010. Stations on *those* frequencies are going to get
> trounced in their hometowns by the skywave coming from the 1000 station's
> IBUZ!

Bzzzzzt!

Once again, I must point out that the 50 kW IBOC station puts, not 500 W, but 
1.3 kW of digital power on each first adjacent (1.5 kW if they throw the 
'high power' switch that is embedded in the NRSC-5 standard, which is 
presumably fine as far as the FCC is concerned).  Experience with the DRM 
system has shown that, in terms of causing interference, an OFDM digital 
signal like IBOC is equivalent to an analog signal having carrier power at 
least 6 dB higher than the average digital power.  That means, in effect, the 
50 kW AM station is deploying two new 5 kW stations on its 1st adjacent 
channels.  Stand back... it ain't gonna be pretty.

For review of the numbers, see 
http://topazdesigns.com/iboc/AM-IBOC-Parameters.html

Barry

-- 
Barry McLarnon  VE3JF  Ottawa, ON