scanthewaves
Member
Whenever I listen to a P25 system audio seems garbled with too much modulation, makes me wonder if the units hear it the same I do on their radios?
P25 Garbled Reception
- Thread starter scanthewaves
- Start date
- Status
Which system?
Garbled transmissions are quite common when trying to monitor a Simulcast system with a scanner that does not handle that well.
- Joined
- Feb 22, 2007
- Messages
- 6,489
And what radio? LOL
MStep
Member
I concur, and as has been noted many times here in the forums, the radios that most of us are using, like the Unidens and the Whistlers, are just hobbyist devices--- I'm always surprised that they work as well as they do considering the fact that they cost a fraction of commercial radios.
JethrowJohnson
I love P25
What kind of scanner are you using?
scanthewaves
Member
436hp
scanthewaves
Member
436hp
JethrowJohnson
I love P25
Okay. And what city are you in?
scanthewaves
Member
Kingsville TX I just tried a Digital AGC tweak and it improved a bit, I've been told on the Texas forum that the system isn't simulcast but now I'm not so sure.
JethrowJohnson
I love P25
Sorry, is that Kleburg County or Nueces County? The database is showing two counties for Kingsville. I don't know if there's a township named Kingsville too, or if maybe it could be on the county line?
The Kingsville system, in Kleberg County, is simulcast.
Kleberg County Public Services Trunking System, Kingsville, Texas
Kleberg County Public Services Trunking System Profile
www.radioreference.com
There only two sites for transmitters, but it is simulcast.
Looking at the details on the for the Coastal Bend Regional Interoperability system, it appears that the database (in RR) does not correctly identify two of the sites.
Coastal Bend Regional Interoperability Network Trunking System, Varies, Texas
Coastal Bend Regional Interoperability Network Trunking System Profile
www.radioreference.com
Site 2, Flour Bluff, is not listed correctly. It only shows one frequency, listed on the system's page, is 853.425. There are other frequencies at that location, on license WPWX340.
However, looking at Site 5, Shoreline, it shows as licensed on KNNY532. If you take a look at that license, 8 of the 15 frequencies listed for Shoreline are also licensed at Flour Bluff.
What is complicating the matter on the Coastal Bend system is that the current system used for the Corpus Christi area, for the Four County Coastal Bend Interoperational System, which is EDACS, is being phased out, transitioning operations to the newer system. Once that transition is complete, and someone in the area can correctly map out exactly how the sites are set up, then it may well be that other sites are simulcast as well.
There have been a couple of threads in the Texas forum on talkgroup status for Port Aransas as well s a Corpus Christi talkgroup. Once the changeover is complete (I'm not in that part of the state), and things settle down, hopefully the corrected information can be gathered & submitted to the database.
scanthewaves
Member
Sorry it's Kleberg County
scanthewaves
Member
So does that mean that if that frequency is left out it will affect proper reception and yes I"m one of the contributers to that Port A thread, I was there and I have been able to monitor Port A on that P25 system, it too must be simulcast as it seemed garbled as well. I don't understand how that newer system can be better with only 3 towers VS. the existing 5, I would think some areas might be affected by the range of these towers.The Kingsville system, in Kleberg County, is simulcast.
View attachment 130090Kleberg County Public Services Trunking System, Kingsville, Texas
Kleberg County Public Services Trunking System Profilewww.radioreference.com
There only two sites for transmitters, but it is simulcast.
Looking at the details on the for the Coastal Bend Regional Interoperability system, it appears that the database (in RR) does not correctly identify two of the sites.
Coastal Bend Regional Interoperability Network Trunking System, Varies, Texas
Coastal Bend Regional Interoperability Network Trunking System Profilewww.radioreference.com
Site 2, Flour Bluff, is not listed correctly. It only shows one frequency, listed on the system's page, is 853.425. There are other frequencies at that location, on license WPWX340.
However, looking at Site 5, Shoreline, it shows as licensed on KNNY532. If you take a look at that license, 8 of the 15 frequencies listed for Shoreline are also licensed at Flour Bluff.
What is complicating the matter on the Coastal Bend system is that the current system used for the Corpus Christi area, for the Four County Coastal Bend Interoperational System, which is EDACS, is being phased out, transitioning operations to the newer system. Once that transition is complete, and someone in the area can correctly map out exactly how the sites are set up, then it may well be that other sites are simulcast as well.
There have been a couple of threads in the Texas forum on talkgroup status for Port Aransas as well s a Corpus Christi talkgroup. Once the changeover is complete (I'm not in that part of the state), and things settle down, hopefully the corrected information can be gathered & submitted to the database.
If your missing a freq, it will affect reception. If its a voice channel, and it's missing, you will never hear any voice thats on that freq.
JethrowJohnson
I love P25
I thought the control channel would tell it the frequency to tune to?
Last edited:
While the 436 does do control channel only, as listed in the manual, it does also say, " With Motorola trunking frequencies, you do not have to program voice channel frequencies. " .
Is system in question Motorola?
Is system in question Motorola?
Project25_MASTR
Millennial Graying OBT Guy
That's not how P25 works in a trunked environment as the control channel tells the devices listening where to follow to track the system. Control channel data (downlink) includes information related to SID, WACN, Site ID, Sys Manufacturer, callsign, site affiliations, band plan (which can optionally not be advertised though it's trivial to figure out when comparing frequency data to control channel data for that site), alternate control channels, active channels (and talk groups), and adjacent site info (Site ID, active control channel, etc). Anyway, as long as the control channels are known and band plan is known...any device capable of tracking per the spec should be able to follow the system without knowing anything other than the active control channel, band plan and talk groups of interest.
To the best of my knowledge the BCD436HP, SDS series and TRX series all support this in my limited fiddle farting around with them.
With a Harris trunking system, all voice channels are also potential control channels as well. Harris systems are designed to rotate control channels frequently. You need to enter the voice channels just because they are considered control channels as well.
Project25_MASTR
Millennial Graying OBT Guy
Theoretically, it shouldn't matter as once the radio finds an active control channel as it will learn the site's alternate control channels and adjacent sites. Now I don't expect the scanner manufacturers to actually follow the part of the spec where the radio learns the site's alternate control channels (nor do I expect the scanner to learn adjacent site info).
Scheduled control channel rolling...is more of a legacy function dating back to analog trunking systems when repeaters were passively cooled, often installed in uncontrolled environments, and/or controllers could be interfaced to just about any manufacturer's repeaters (including two mobiles strapped together). Not necessarily needed today...but I could see practical applications of using it today still and Harris is known for doing some strange things (not necessarily obvious when compared to Astro 25/Atlas/Tait/Etherstack) with VIDA.
- Status
Similar threads
