P25 Phase 1 and Conv. squelch questions

[bfletcher]

Hello. On a particular Project 25 Phase 1 system I see 1 [red] control channel but the other three frequencies are neither red nor blue; they are simply listed in a black font with no footnotes. Do I need to program those frequencies?

Also; on a given conventional frequency, once the voice terminates I hear a 1 second static sound. Might there be some tweak I can attempt to eliminate this?

Thank you

 

[DickH]

Hello. On a particular Project 25 Phase 1 system I see 1 [red] control channel but the other three frequencies are neither red nor blue; they are simply listed in a black font with no footnotes. Do I need to program those frequencies?

Also; on a given conventional frequency, once the voice terminates I hear a 1 second static sound. Might there be some tweak I can attempt to eliminate this?

Thank you

Re. the freqs. you should put them all in because some systems rotate the control channel from time to time.
Re. The sound you hear is called "squelch tail" and there may be a setting in your scanner to help eliminate it. Is it really a whole minute?

 

[N8IAA]

Hello. On a particular Project 25 Phase 1 system I see 1 [red] control channel but the other three frequencies are neither red nor blue; they are simply listed in a black font with no footnotes. Do I need to program those frequencies?

Also; on a given conventional frequency, once the voice terminates I hear a 1 second static sound. Might there be some tweak I can attempt to eliminate this?

Thank you

What trunk system? What conventional frequency?
Can't answer without that info.
Larry

 

[troymail]

Hello. On a particular Project 25 Phase 1 system I see 1 [red] control channel but the other three frequencies are neither red nor blue; they are simply listed in a black font with no footnotes. Do I need to program those frequencies?

Depends.

For better performance - particularly on systems that exhibit digital simulcast issues - it may be prefered to only program the active/primary control channel. However, if that control channel frequency changes, you may "go silent" for that system.

If you're not dealing with digital simulcast issues, program all of them.

 

[bfletcher]

Is it really a whole minute?

No, lol. a full second, occasionally 1.x seconds. Are you aware of any such tweak on WS1088? Thx.

 

[bfletcher]

What trunk system? What conventional frequency?
Larry

1. Ohio MARCS-IP: Multi-Agency Radio Communications (P25). Preble County's West Alexandria site. TG is Sheriff Dispatch 54854. 773.30625 is listed as the control channel; the other three frequencies are not listed as c nor a.

2. 159.3825, Preble County's Fire Dispatch. This is where I hear the squelch tail as noted by DickH. My BCD436 does not exhibit this but the WS1088 does.

Thx

 

[bfletcher]

If you're not dealing with digital simulcast issues, program all of them.

If digital simulcast issues sound like the adult voices heard but never seen on Charlie Brown then, yes, I'm experiencing this issue on the WS1088 (but not the BCD436). By simulcast, currently our P25 system is also being broadcast on 155.61. If and when that ends will this issue resolve itself, or do I have the wrong understanding of digital simulcast? I've read some posts here and on wiki about playing with squelch, programming only one site, and trying only the primary control channel, all three of which I am currently experimenting. Also mentioned is attenuation but I need to seek more understanding before being able to comprehend what and where (within the software) I explore that option. Thx

 

[DickH]

If digital simulcast issues sound like the adult voices heard but never seen on Charlie Brown then, yes, I'm experiencing this issue on the WS1088 (but not the BCD436). By simulcast, currently our P25 system is also being broadcast on 155.61. If and when that ends will this issue resolve itself, or do I have the wrong understanding of digital simulcast? I've read some posts here and on wiki about playing with squelch, programming only one site, and trying only the primary control channel, all three of which I am currently experimenting. Also mentioned is attenuation but I need to seek more understanding before being able to comprehend what and where (within the software) I explore that option. Thx

Simulcast means when more than 1 tower transmits the same information SIMULTANEOUSLY. Then there is a problem with phase shift between the signals from the various towers. That may be what you are hearing.
The squelch tail is a separate issue - no connection.

 

[AggieCon]

Open squelch for P25

Howdy,

I suggest trying to resolve each issue separately. My experience is that monitoring a single trunked system provides be best experience. It's just not as efficient to keep jumping around, in and out of the P25 system, causing the the scanner to only decode a fraction of the control channel data stream. You might consider getting a cheaper conventional scanner to dedicate for monitoring the fire dispatch channel.

I looked up the P25 site you described, and it doesn't appear to be simulcast.

Aside: In multi-site trunked systems, there are two main configurations: multicast and simulcast. In multicast, each tower operates independently on frequencies different than nearby towers; it repeats traffic only relevant to its service area (i.e. a radio on that talkgroup is in range). In simulcast, which radio traffic carried is similar to if it were just a single multicast site; however, in simulcast, there are multiple towers broadcasting the same traffic on the same frequencies. This is a more complicated arrangement, and multipath and phase shift due to varying transmitter distances commonly introduce problems. Fortunately, you don't have to worry about that.

To improve your P25 reception, it's best to have the squelch open (all the way down) and program only the live control channel. The idea is to have the "T" icon constantly lite -- that means the scanner is decoding the control channel. For a P25 system, the control channel tells the radio the voice channels, so those don't need to be programmed (unlike an EDACS system, for instance). When the squelch is higher, the radio will search for the signal again whenever there is a drop in the digital signal below the squelch setting, causing the the decode to start and stop (whereas if it just stuck to decoding it wouldn't miss much). If you have multiple frequencies programmed, it is going to search all of those for a strong control channel. When the squelch is open, it stays on the control data stream.

If you have multiple sites programmed, this further complicates the issue, as the radio will scan through all the sites (and each frequency for each site) looking for what it thinks is a good control channel decode. Be sure you have just the site you are near programmed into your radio, especially if you are trying to monitor a conventional frequency too.

You can program the possible control channels as conventional frequencies and listen to them via the browse menu. It will be unmistakable which is the control channel vs static.

The problem with leaving the squelch open is it's incompatible with conventional scanning. So if you must monitor both, set the squelch as low as possible, as mentioned by a previous poster.

As far as the trailing on the conventional channel, it could just be their equipment. However, you might try listening with the squelch tone on (i.e. 118.8 PL), and then try removing the squelch tone (set it to search). It's been reported by others that they have better performance regarding trailing noise without the squelch tone set -- perhaps an issue with the repeaters. Many of the conventional channels I listen to are patched from trunked systems, and the radio infrastructure sends trailing static -- it's just something I have to deal with when monitoring those frequencies.

In summary, for the P25 system, try it alone with just the single site and single control channel with the squelch open. For the conventional, try it with the squelch tone on and then off.

Good luck!

 

[bfletcher]

Thanks for the clarification, DickH

 

[bfletcher]

AggieCon - thanks for providing such in-depth detail; I appreciate it. On the conventional fire I did remove 118.8 PL and for two days running it has worked well, except I set it to none rather than search - I will change it to search. On P25, I'll wrap my head around all you've suggested--some of which I tried after reading several posts--but thus far it is still a frustrating endeavor. For me here in my area my BCD436 works flawlessly (and required no tweaking) but this WS1088 is giving me fits. It is a love-hate relationship with the BCD436 because the WS108x series menus just naturally click with my mindset and I love the flexibility of selective recording, along with not having 100-count sessions (and the fact that the record option does not default to off). I'll continue for a span of time to see if I can find favorable P25 results with the 1088. Thanks.

 

[bfletcher]

When I experiment using control channels only do I move it's LCN from--in my case--position 4 to 1?

 

[AggieCon]

The LCN order doesn't matter for P25. I think the Radio Reference database just does the list in smallest to largest. It's probably fine in slot 4, slot 1 or any slot. Now that I am comfortable with the scanner, I usually program everything myself rather than importing... something to consider. Anyways, I always start with slot one and add to it as they swap the control channel to something new (I do this "as needed" process so I have only what is absolutely needed, rather than loading frequencies they may never use for the control channel). Keep in mind a frequency in the Radio Reference database could be a control channel for some unrelated nearby system -- something I've ran into before. So it's really best to limit the number of frequencies to just what is actually used.

I assume you are doing the programming with the software. It can also be done through the radio on the fly, but this is a little clunky:

"Program Menu" -> "Edit System" -> Select your system -> "Edit Sites" -> Select your site (btw the site number in the scanner doesn't have to match the system site assignment) -> "Frequencies"

On that page, you can add, edit, and delete the frequencies it uses to search for the control channel. After making the change you would:

"Save Changes" -> "Save Changes" -> "Back to system" -> "save changes"

I mention this process in case they change the control channel frequency while you are away from the computer.

If your menus are different than this, make sure you have the latest firmware. I am using the WS1080, but the firmware is virtually identical I believe (when they released the WS1088 there was a big change to the WS1080 firmware).

"None" is probably best for the squelch. I would leave it there. I just said "search" because that is the default. Not really sure of the difference, except on "search" if you are paused on the frequency during or after a call you can hit menu then save the tone that it found.

What antenna are you using? As an experiment, you might swap the two antennas and see how each radio performs.

Also, try different locations. Reception on my favorite P25 system was pretty poor in most places in my apartment, however, when I put the radio on a stand (empty box) 18" above my desk, I get 100% decode and perfect reception on both phase 1 and phase 2. Elsewhere in the apartment it is hit or miss... same on the road. If the WS1088 has marginal performance compared to your other scanner, it could make the difference.

Check out this guide if you haven't already, it's a great help: Select

You're welcome. I hope you are able to get it working.

 

[bfletcher]

Thanks again. I've experimented with the stock antenna, RS' 800MHz, Diamond's RH77CA and RH789. No base antenna. So far, I'm programming via software and manually deleting TG's of no interest. Self-programming is something to think about.

 

[AggieCon]

The RS 800 is probably the best out of that bunch for this system. The 7inch antenna at the following link is what I've found to work well in that range (it's similar to the RS 800, which I don't have): http://www.amazon.com/ExpertPower®-...&redirect=true&ref_=oh_aui_detailpage_o08_s00

Regarding the talkgroups you aren't interested in, it's probably best to leave them programmed and lock them out. That way, if you want to run a wildcard to identify new talkgroups on the system, it will ignore the talkgroups you don't have interest in; otherwise, the wildcard will pickup the groups you don't want to hear.

I forgot to ask. Does your reception issue occur with both the control channel decode and the calls, or just the control decode? Oftentimes even with a poor decode I will get crystal clear voice traffic (though maybe miss the beginning of the call), and then if reception further falls off, I lose both. If you are able to achieve good voice call decode quality, then I am confident you can get this to work well.

 

[bfletcher]

Thanks for the wildcard tip. I don't have enough knowledge to understand your question regarding control decode vs. voice. When running both the WS1088 and BCD436 at the same time in various locations within a room, compared to the BCD the WS either doesn't land on a transmission at all, or it is garbled--most of the time. On rare occasions it does pick up well. And at other times, if the transmission time is long enough it sometimes starts off well but then the voice quality begins to deteriorate. And I sometimes try it without the BCD running, too. Thanks.

 

[AggieCon]

That's what I was asking. Kinda disappointing that it appears the Whistler isn't as good as the Uniden as far as reception of marginal signals.

For me, with marginal reception, location is key. Literally a few inches can make the difference between good and bad. Before figuring out sweet spots for reception, I was getting pretty frustrated and mad at the scanner (it's expensive, right...). Besides continuing to experiment with locations and antennas (one thing you might try is directional pointed at tower), you might try the following:

Experiment with attenuation settings. Maybe the signal or something nearby in frequency is really strong (like a cell tower for instance). There are three ways to do this: global, system, or site. Some people have reported success on the forums after they attenuated it on the site level (in EZ Scan go to Trunked tab, then the system, then under Site Details the site in the table on the bottom left). Here's one example: http://forums.radioreference.com/whistler-scanners/322143-700mhz-p25-phase-2-reception.html Make sure the Attenuation Mode on the General Settings tab on EZ Scan is set to normal.

On the Advanced Features tab, under Advanced DSP Settings, you can adjust the DSP Level Adapt, ADC Gain, and DAC gain.

The Digital Signal Processor (DSP) level supposedly adjusts the processor speed to better sync with the signal (I'd like to have a better explanation on what exactly this value is modifying). It has a huge range of options, and everyone seems to report a different value that is best. I'm not convinced that it matters much, but it's something to try.

The Analog to Digital Converter (ADC) gain is something worth playing with, and there are only 5 settings here. I'd try +2 then -2.

The Digital to Analog Converter is just how much power is set to the speakers. I usually keep mine modestly low since the digital systems blast out of the speakers compared to conventional analog reception. This setting isn't going to impact your decode.

Here's some threads with what others are saying about these values, and there are more if you search them out.

http://forums.radioreference.com/ra...ing-adc-dac-gains-pro-668-other-scanners.html
http://forums.radioreference.com/whistler-scanners/319870-ws-1080-dspleveladapt-question.html
http://forums.radioreference.com/wh...80-digital-longer-they-talk-clearer-gets.html

By the way, if you don't see some of these tabs on the EZ Scan app, make sure they are selected under the "Advanced" drop down list on the menu bar.

 

[bfletcher]

Thanks again! I tried attenuation but didn't realize there were multiple methods with varying results. I became so frustrated yesterday that I need a full day's break today but I will look at it again tomorrow. I'm in a rural area but, yes, we have a cell tower visible from our window at approximately 1/4 mile. Well, I think it's a cell. I am told it is.

 

[bfletcher]

Well, I lied; after reading your post I couldn't resist but to play with the DSP level and ADC gain. After several random attempts I have discovered a DSP setting that has resulted in vast improvement. But since I don't know what I'm doing--nor exactly what it does--I'm just grasping at straws at picking settings and I don't have a decade to try all possible combinations. So, for now, I at least feel I have the possibility of honing-in on a viable workaround. Albeit, right now I'm only experimenting with this on a single talk group, so I don't know if a setting that works on Preble Co. Sheriff dispatch will have an adverse effect on other systems and sites. But thanks again for taking time to offer help!

 

[AggieCon]

Good deal! Which way did you go with the DSP? I suppose a sticky thread with everyone's luck would be a good reference. Is the talkgroup you're interested in broadcast in phase one or phase two (does the icon show "D2" or "DG/D/DA"?)? For some reason, I tend to get better decode on Phase 2, even though it's more complicated...