The idea with simulcast is to keep the non capture area as small as possible. Typically the capture area is that where the dominant transmitter has a 10 dB or greater advantage. In capture areas subscribers hear only one signal A good test is to broadcast different audible tones from each site and see which tone is heard.
Running as high power as possible keeps the capture areas as large as possible and minimizes non-capture areas. For simulcast to work the signal in the non-capture area needs to arrive in the non-capture area at the same time from each contributor. Most systems are designed in a straight line so that the outer sites don't overlap. The GPS signal is used to discipline a master oscillator at each site. Every transmitter uses the same MO. Depending on the number of channels, you may want to use receiver voting along with bulk delay in a 1.544 mb/s T1 stream. Contact Ed O'Connor at Simulcast Solutions or visit their site for some good information. http://www.simulcastsolutions.com/ 73 Steve NU5D Bill Powell wrote: > I'm considering a trunked (type TBD) system on 470 that will have > significant on-channel overlap. > The overlap comes about due to the need for multiple sites to fill the > many holes that will exist with a single site regaurdless of location > or (reasonable) tower height. > Assuming that ALL the transmitters are GPS locked and properly set up > for simulcast operation, what operational problems might I expect? > > Thanks, > Bill Powell > > > > >
