[BC] Arbitron

[Warren Shulz]

You got to admit that the PPM process has some Voodoo associated with
it.  This discussion is good information for the knowledge pool.  In
Chicago both WLS-AM and WLS-FM have enjoyed favorable PPM results.  I
was very pleased with the cooperative knowledge of our Arbitron contact
and the flexibility of working out local installation details.  

I had one idea to isolate the watermark....Take the input audio and
phase audio to a null with the output of the PPM encoder.  What is left
over should be the watermark. Never tried that but believe it would
work? 

To add to the knowledge base pulling the AC power causes a graceful fold
back to bypass mode.  So in about 5 years when the switching supply dies
it will fail to bypass and not cause a program outage.

Warren Shulz
WLS CGO

-----Original Message-----

 From: Gary Blau

The RS-232 output isn't any more helpful than the idiot light, because 
the data it spits out every 20 seconds is not an indicator of whether or

not you actually received a good burst in those 20 seconds, but rather 
that the 3 minute 'rolling window' is satisfied or not.  IOW, the same 
as the idiot light.

It also doesn't give you a time or date stamp, so you can't use it for 
logging in a meaningful way.  It does tell you the callsign of the 
encoder it 'saw' during that 3 minute window, but that's it.

If it gave you a time stamp for each 5 second, or even every 20 second, 
window, then that would be pretty helpful.  Maybe in a later model, we 
can hope?

There seems to have been some mixed info from Arbitron about the 
importance of using an external time sync source.  We were told it was 
the preferred way to go, so all of our units, with a couple exceptions, 
all are driven by an ESE master clock.  The exceptions are for emergency

encoders at tx sites that would be enabled in case the main and backups 
fail.  The internal clocks in the encoders drift over time, and could 
eventually end up significantly in error with real time.  There is no 
way for the user to set those internal clocks.  You have to specify in 
advance whether the unit should have its external clock port enabled or
not.

Even with the external time code, there have been occasional odd alerts 
that still remain unexplained.  The external sync circuit and its 
behavior seems to be not robustly thought out.  Again, hopefully in 
future models they'll have those fixed.
We haven't had any significant trouble with ours so far, though.

g

Warren Shulz wrote:
> You can connected a PC to the RS-232 port of the PPM decoder and get
> a line entry that repeats over and over.  Another issue is clock.
> Seems the down load will track and correct clock error.  We never did
> get he external clock to work and it was not important from what I
> was told.
> 
> That is an important point - dead air and no PPM.  So if you loose
> audio no encode action. Ah but then the PPM decoder also calls for
> help with dead air.,  You may want to have a time delay on that
> status channel to stop false calls.
> 
> I found it interesting the decoder ( hands of listener) has a motion
> detector.  Lack of movement an d it stops logging.  I suggested
> clipping the PPM unit the dog's collar!
> 
> Warren Shulz QLS CGO
>