Batboard

Why do some of our Astro receivers have a reference module and some do not.. ????

You may be referring the HSO option... High Stability Oscolator.

Other's can chime in here more than I know, but its an option for the Quantar that allows extremely presice on freqency, tight deveation. USually they are ordered for SmartZone and simucast systems. I believe they also use GPS time signals to help, but not a 100% sure.

Lemme see if I can dig up the offical information.

The High Stability Oscillator (HSO) module is used exactly as PJ said. It's primarily used for simulcast systems that require an extremely high level of frequency stability so as to facilitate properly timed and synchronized simulcasting. They help eliminate the heterodynes when two signals occupy the same frequency at the same time. Some use GPS-based synchronization, others use a Rubidium standard.

This is most common in 800 and 900MHz systems, but can also be found in VHF and UHF simulcast systems.

HSO is also common in paging applications, as they are generally simulcast systems as well.