Trunking info requested - help with sites

wh6diq

Member
Joined
May 30, 2016
Messages
29
SDS200, Honolulu County Public Safety System (EDACS). I am seeing significant changes in reception quality that I do not understand. For this discussion, I assume there can be differences from mobile units due to variable locations...my focus here is on the dispatch transmissions. I can monitor a tx from, for example, Waikiki site, or Metro Simulcast site. Within the span of seconds, quality changes from perfect, with RSI of 103 - 106 and showing 3 bars signal strength, to 1 bar and broken tx. RSI no change. Noise levels vary generally very lowest around 350, highs with readable or broken tx can be 900 or higher during a single tx. Same dispatcher, same patrol officer, same TGID, same freq, same site. This seems to occur more frequently on the Metro site. Typically, if a tx is good quality, it remains so until one party unkeys, then may follow the call ok, or it may be broken, even though the scanner does not resume scanning before the second party keys up. If it has resumed scanning, may or may not pick up conversation good quality again. Another key up, and all is good....makes no sense to me.

Visually, I have a more clear line of sight to the Waikiki location. I am in a highrise, 4th floor, Makiki area. The Metro site likely has more high rise buildings between my location and tower (although I have not determined exactly what building either of these sites are located on, but based on general geography..) I am within 3 or 4 miles of both (The entire island/county is less than about 30 miles tip to tip in any direction, but does have challenging terrain dividing major areas.). I am not real close to other high rises, with over a block between me and the nearest in one direction, and 2 -3 blocks in the opposite direction, I'm generally located in a single family home and low rise housing area. I can see 5 different cell system antenna installations, nearest about 1 block away, and 100 feet above my location. No idea if these have an effect...

I am wondering if I need to scan all sites, while operating as a base unit? I am interested only in HPD district 1 for normal monitoring, if I just monitor one tower or the other, would I likely hear all district 1 traffic? (Actually I want to monitor the Fire Dispatch and EMS Dispatch on the same system, but no need to confuse this discussion...)

Antenna issues have already been addressed to the best of my ability, although I am considering an 800 mhz yagi to point generally at one of these two locations. Probably will not try this until the New Year... There are no other reception issues, only some broken tx on the EDACS County System, HFD, HPD, EMS. Federal Fire, Air, Amateur Radio, Miliary and Commercial Air, all are quite good, and the EDACS County System is around 90% good.

Lastly, wondering if there are any audio files that demonstrate some of the types of interference and simulcast decoding issues that are common? Maybe I am trying to fix the wrong problem!

73
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
10,093
Location
PA
The SDS200 doesn't have simulcast decoding issues. It's designed specifically to correctly handle simulcast systems. A yagi probably isn't necessarily going to help, and will degrade reception for everything it isn't pointed at out of its frequency range.

Set your scanner to detail display mode so you can see the frequency during each transmission. Most likely the trouble is on one or two specific frequencies. Make a note of which ones are problems.

Interference from cellular is a possibility.
 

wh6diq

Member
Joined
May 30, 2016
Messages
29
Update... I have deleted sites that are distant, and reorganized the system...deleting duplicate departments. Significant improvement! I had to do some digging in the site maps etc. to really locate the towers, but it was worth the effort!
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
10,093
Location
PA
All of the sites in the database are already tagged with their location coordinates.
 

wh6diq

Member
Joined
May 30, 2016
Messages
29
Not for Honolulu County Public Safety... many have the same coordinates for multi sites. You have to dig deeper to find address or useful location info.
 
Top