THE PURPOSE OF THIS PAGE IS TO PROVIDE PRACTICAL ADVICE ON MONITORING THE WESTMORELAND COUNTY APCO25 SYSTEM.
Over the course of the past five years we have made observations, received comments and answered questions which have led us to write the following. Most of this is information helpful to understanding what makes the APCO25 800 MHz system different from the conventional FM analog systems you've previously monitored, and how you can better understand how it works and what you are hearing.
OK. HERE WE GO....
- Q. Why do I need a new scanner to monitor Westmoreland County's 800 MHz system? I've listened to Fayette County on my old trunking scanner? A. This new system uses a totally different type of radio communications called digital modulation. This means that the voice signals are sent over the airwaves as a series of 1's and 0's instead of a varying frequency (which is used in FM, or frequency modulation).
- Q. I bought a scanner at a flea market/garage sale/internet site and they told me it was capable of receiving 800 MHz trunked systems. Can it receive Westco's new system? No. The radios which have been sold over the past few years and advertised as capable of receiving trunking signals are only able to receive those trunked system which use traditional FM modulation to transmit voice communications, with these voice channels then being "trunked." The new Westco system uses digital modulation; thus, you MUST purchase a new APCO25 capable scanner as these are the only units which can receive and decode digital modulation. If you try to monitor one of the Westco 800 MHz frequencies on the non-digital scanners you will only hear a static-like noise instead of voice. This static sound is what digital radio signals sound like when not properly decoded.
- Q. I read somewhere on the web that the PRO-2052 [or insert the scanner name of your choice here] can be modded with a keypad hack to receive the digital modulation. How can I do this? A. You can't. This is fiction. We read this one too; we bravely went where no man had before and bought the 2052 on sale just to try this out. We tried every hack we had read, examined the circuitry, saw that it lacked a digital demodulation circuit and concluded it couldn't possibly work. So we returned the radio to Rat Shak. In short, this myth grew out of a comment in the Instruction Manual which refers to Motorola trunked systems and makes confusing use of the word "digital" in the same paragraph.
- Q. What about the "talkaround" channels? A. Ok. You CAN listen to the talkaround frequencies using a regular 800 MHz scanner, since these are old-fashioned FM simplex radio transmissions. These frequencies are 867.0125 FIRE talkaround, 866.5125 EMS talkaround and 866.0125 POLICE talkaround. For information on other possible talkaround frequencies, see the Frequencies page.
- Q. Why did Westmoreland County go with APCO25 versus keeping/upgrading their VHF FM system? A. These frequencies were licensed years ago by the County, and the FCC had given licensees a deadline to have their frequencies occupied by "up and running" systems, or lose the frequency assignments to other users. Among other, more political, reasons...
- Q. Why do I hear garbled squawking sounds from some units and not others during the same series of radio transmissions? A. The garbled sounds are voice encryption (scrambling). The fact that you hear some units clearly and others scrambled indicates that those units do not have their scrambling feature activated while transmitting. However, these units "in the clear" can still hear the decoded radio messages from the unit they are communicating with.
- Q. Why do I hear units from all over the County when I am trying to hear my local police/fire/EMS? A. The ability to hear units, including mobiles and portables from the farthest reaches of the county 24-7 is one of notable characteristics when monitoring this system. You are able to hear them because the system consists on number of interconnected repeater towers which repeat all communications in their zone of the county, and under certain circumstances, in both zones of the county system. After listening to all the talkgroups, you may find that you aren't interested in listening to police transmissions from distant districts, so just lockout those talkgroups from your radio's scan menu. Unfortunately, this
- Q. Why do some radio signals suddenly become distorted in mid-sentence? A. Think about monitoring this radio system as you would listening to someone on your digital cell phone. You probably notice that during cell phone conversations, you sometimes cannot hear the person you are speaking with on the phone, or their voice sounds distorted. This is characteristic of digital 800 MHz radio transmissions, particularly in mountainous terrain like we have here in Westmoreland County, and is caused by signal fading either between the unit transmitting and the radio system's tower and/or between the tower and your scanner. Nothing is wrong with your radio; this is merely something you have to live with in monitoring digital signals in the 800 MHz band in mountainous terrain. If you receive signal strength is good and you want to try to "tune up" your radio to receive better, see the following Q./A.
- Q. I see something in my Bearcat radio's instruction manual about "Optomizing P25 Performance" or "Setting APCO25 Sound Quality"? What should I do? A. This is something new to scanner listeners and comes with the territory when monitoring a digital system like Westmoreland County's. Essentially, you are adjusting how the receiver decodes the 9600 baud digital data stream which contains the voice transmissions you are trying to hear. These instructions, found on page 51 of the BC796D manual and page 99 of the BCD396T manual, tell you how to fine tune the digital decoding circuitry to decode as close to 100% of the digital stream as possible. Follow your radio's instructions carefully and play with this adjustment a bit and you should see improved audio quality. If you don't feel comfortable making these adjustments, you are probably safe to leave the radio on the default/auto settings, particularly if your rig is a mobile or portable used in various locations.
- Q. Do the actual police/fire/EMS radios have these problems receiving? A. Sometimes. Ever notice how often mobile units ask 911 to "repeat the numerics" on addresses? Any radio's ability to receive and decode the digital signals consistently is effected by signal strength (which in turn is influenced by it's distance from a transmitting tower, and any natural or man-made structures in the signal's path) and your radio's digital stream decode settings described in the question above. Their radios, however, have circuitry which can automatically adjust the digital decoding rate of their receiver based upon information sent on the control channels.
- Q. Now that I've purchased a new digital scanner for the 800 MHz system, do I still need to keep my old scanner? A. All the APCO-25 digital scanners produced by Bearcat/Uniden and Radio Shack can monitor not only the new 800 MHz digital system, but also the analog FM and AM aircraft frequencies as well. Theoretically, you can monitor ALL of the old FM channels as well as the 800 MHz digital stuff on one radio, and this practically what mobile or portable listeners should do as a matter of practicality and convenience. For listening at home, however, there are several reasons why you probably shouldn't toss out that old analog scanner. First, a year of monitoring this new system has demonstrated that the new 800 system tends to tie up your radio for extended periods of time on what are often routine, less interesting radio traffic. If you're in Monessen, do you REALLY care if a fire department portable on Fire Tac 10 in Derry Boro is communicating with 911? Likewise, if you are interested in EMS dispatches do you really appreciate being able to hear ALL portable to portable routine communications on District 9 PD dispatch? NO. But that is nature of the using repeaters as the 800 system does. But even if you lockout the talkgroups you're not interested in, the 800 system still generates alot of radio traffic. Second, one year after the 800 system was implemented, fire and EMS dispatches are STILL tone dispatched on 33.70 and 155.160 MHz, respectively. For those of us who are old hands at monitoring we'd still prefer listening to these channels on a SEPARATE scanner, along with state police VHF-FM channels, and local EMS units still dispatched on 155.160 MHz, as well as road maintenance crews, utility companies, etc. The problem is, if you try to monitor your favorite FM analog channels still in use on the same radio which has the 800 MHz system, the scanner will usually be tied up on some 800 talkgroup or another for extended periods of time AND WHILE THIS IS HAPPENING, YOU WILL NOT HEAR ANYTHING ON THE FM ANALOG CHANNELS. So to keep up with all the radio action on those still-active FM analog channels as well as the new 800 digital stuff, pa2600.com recommends using both your old scanner and new scanner at the same time. This will also give you the capability to separately adjust the volume on the two types of systems, which can make your listening more enjoyable. Finally, if the new system were to seriously malfunction there would be large parts of the County where the old FM analog radio channels would be the only means of communicating for those departments wise enough to hang on to their old radios! (Just something to think about. Who knows what might happen a few years from now when the "grant money" dries up and the maintenance costs of the complex proprietary 800 digital system skyrocket and are dumped in part back on the fire/police/EMS agencies using the system. Don't think it can't happen! We could see a reversion to the old FM analog dispatching in such a situation. Another good reason that listeners [and local emergency services agencies] should keep their old FM rigs.)
- OK. That's about it for now. There's more information we want to cover, so check back often AND SEND IN YOUR QUESTIONS AND SUGGESTIONS!!!
As stated above, this page represents the personal opinions of Levitis Leviathan and the personz of interest. It does not represent the opinions of any advertiser or other person. Send your questions, comments or suggestions to us at COMMENTS2007 [at] pa2600 [dot] com. We will try to post our best answers/guesses to questions here so send them in and check back often!
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