UHSO on Quantar for 12.5 kHz Operation

ASTROMODAT · Post by **ASTROMODAT** » Tue Jan 14, 2003 2:24 pm

The current R3 catalog (Oct - Nov, 2002) states that the UHSO ($2,000 additional) on the UHF Conventional Quantar is necessary for 12.5 kHz P25 conventional operation.

Is this really necessary?

I'm a bit perplexed, as the ASTRO P & M are certainly not stable to 0.1 PPM.

Larry

Post by **wavetar** » Tue Jan 14, 2003 5:26 pm

The only time I've seen those UHSO's needed were in Simulcast systems. I don't see why it's "necessary" for 12.5KHz P25 operation...unless it's written somewhere within the P25 specs. If you have several repeaters at the same site, a Rubidium oscillator is even more accurate & cost effective, as you can input it to multiple repeaters.

Todd

ASTROMODAT · Post by **ASTROMODAT** » Tue Jan 14, 2003 8:49 pm

The UHSO also includes an ouput to support up to 8 or more additional Quantars. (Does me no good, as I will only have the one Quantar.)

The R3 says the UHSO is required for simulcasting systems, and also for 12.5 kHz operation.

I suppose one can second guess'em, but in the end, I'd hate to have a problem by trying to save on bagging this one option. Just that it's pricey and you don't get any features out of it.

ASTRO_25 · Post by **ASTRO_25** » Sat Jan 18, 2003 5:09 pm

Ok, for us guys that are somewhat literate, but not totally, can you explain what UHSO means?

My guess is "Uniform Something Simulcast Operation" ??

jcobb · Post by **jcobb** » Sat Jan 18, 2003 5:31 pm

How about "Ultra High Stability Option".

What it seems to me.

Jack

Post by **wavetar** » Sat Jan 18, 2003 5:44 pm

jcobb wrote:How about "Ultra High Stability Option".

What it seems to me.

Jack

So close. Ultra High Stability Oscillator.

jcobb · Post by **jcobb** » Sat Jan 18, 2003 7:34 pm

I knew I needed to clean my glasses!

Jack[/i]

Post by **xmo** » Sat Jan 18, 2003 7:55 pm

Here is what the Quantar planner has to say:

"INTERNAL UHSO (X873) = Equips the station with an internal high stability oscillator that fits within the cardcage. Used to provide 0.1 PPM frequency stability for FCC compliance on 900 MHz stations or for 12.5kHz narrowband applications on UHF and 800MHz stations. Not recommended for simulcast applications..."

ASTROMODAT · Post by **ASTROMODAT** » Sat Jan 18, 2003 9:34 pm

Xmo, based on your quopte from the system planner, it IS NECESSARY for 12.5 kHz ops at UHF, unless you have an equivalent external means to provide 0.1 PPM stability (which would likely cost 2-grand anyways).

Thanks, now at least I don't feel quite so bad about having to buy it (since it really is necessary).
Larry

Post by **xmo** » Sun Jan 19, 2003 8:04 am

"Thanks, now at least I don't feel quite so bad about having to buy it (since it really is necessary). "

Maybe it isn't really necessary.

The Quantar Product Planner has a frequency stability table (on pg. 25) that lists the stability for various bands. The basic stability on UHF is 1 PPM. The table lists 0.1 PPM as being necessary for UHF 12.5 kHz analog operation, but there is a ** footnote in the table that says:

"** NOTE: Under certain conditions a Frequency Stability of 1 PPM may be adequate."

Before spending the money for that option be sure of the FCC requirements for YOUR license.

ASTROMODAT · Post by **ASTROMODAT** » Sun Jan 19, 2003 8:58 am

Let's assume that the FCC is O.K. w/ the 0.1 PPM.

Is there any good engineering reason for the 0.1 PPM stability for IMBE ops at 12.5 kHz channnel spacing? (I sure wouldn't mind saving the 2 Grand!)

Larry