Lubbock p25tdma no reception w bcd496hp

[djmorgan]

I have an sds100 and bcd496hp. The sds100 receives all talkgroups on Lubbock city-county mutual radio system. The bcd496hp receives absolutely nothing at all. Both were loaded using zip services. The bcd496 advertises p25 tdma reception but doesn’t. What could be wrong? Ps the bcd496hp receives p25 systems like Texas Tech univ. I can’t see why one would work and the other doesn’t when both systems were loaded at same time and place. Ideas? Very frustrated with BCD m486hp.

 

[hiegtx]

I have an sds100 and bcd496hp. The sds100 receives all talkgroups on Lubbock city-county mutual radio system. The bcd496hp receives absolutely nothing at all. Both were loaded using zip services. The bcd496 advertises p25 tdma reception but doesn’t. What could be wrong? Ps the bcd496hp receives p25 systems like Texas Tech univ. I can’t see why one would work and the other doesn’t when both systems were loaded at same time and place. Ideas? Very frustrated with BCD m486hp.

The Texas Tech system only has a single site. So you should have no issues with either scanner.

The Lubbock City-County system, on the other hand, is simulcast.

The same talkgroup, using the same frequency, is transmitted simultaneously from multiple locations. While the time differentials, for those signals to arrive at your scanner, is small, it is enough of a difference that scanners other than the SDS series cannot reliably receive the system. If you were parked very near one of the transmit towers (like a quarter mile or less), that strong signal might override the out of sync signals from other towers. But that's not the case when you are moving around the area.

See this article in the Wiki for more on how Simulcast impacts your ability to monitor a single system.
Simulcast digital distortion - The RadioReference Wiki

The SDS scanners, as well as the Unication pagers and the Blue Tail receiver, can deal with simulcast systems. For scanners other than these, you'll see varying problems, from no reception at all, to missing some calls, or garbled audio,

 

[djmorgan]

Thank you for such a thoughtful answer. I am at a hotel at 289 and Quaker. It appears the idalou site covers this area and us not simulcast. If I lick the bcd496 on that site should I expect to hear the talgtoups?

otherwise I can see from your map the 496 could not decipher a clear signal to decode due to simulcast “interference “. Again , thanks for the help so much!

 

[hiegtx]

Thank you for such a thoughtful answer. I am at a hotel at 289 and Quaker. It appears the idalou site covers this area and us not simulcast. If I lick the bcd496 on that site should I expect to hear the talgtoups?

otherwise I can see from your map the 496 could not decipher a clear signal to decode due to simulcast “interference “. Again , thanks for the help so much!

The Idalou, Abernathy, & Ransom Canyon sites are fill-in sites.

Notice that each only have three frequencies. They would not carry the full load of traffic that is on the Simulcast, such as most of Lubbock city traffic. The small sites probably would only carry agencies very near them, plus likely county units. Unless a city element was near one of the three smaller sites, you likely would not hear them.

If programming Idalou gets you county units, and that's what you are most interested in, the 436HP should work. That would apply to Abernathy & Ransom County as well.

 

[djmorgan]

Thanks again for such a great reply!

I couldn't get anything from the other sites at all but had to leave town early in the morning and couldn't listen. I did notice, however, that a couple of the simulcast sites are very close together. And Lubbock is very flat so I am guessing the antennas are directional and/or titled or they would overpower even the Motorola public safety radios. This system must have been designed for complete in-building coverage but they are pumping out enough RF to flood the basements, if any buildings even have them. Anyway, thanks.