DCS vs PL?

ExKa|iBuR · Post by **ExKa|iBuR** » Tue Jan 25, 2005 11:18 am

Hi all;

I'm curious to get your thoughts on this. As I've posted in another thread, I'm toying with the idea of getting some kind of repeater on the air, even if just one of those "I want to see if I can do it" kinda projects. Anyway, I was wondering what your suggestion would be in terms of coded squelch. I've generally always used PL on my radios for simplex between friends as I've found that my Motorola doesn't necessarily like to talk to non-Motorola radios when it comes to DCS...a friend of mine has a Kenwood ham rig, and another friend has an Yaesu ham rig - both of which seem to have issues unmuting when I use DCS, but work perfectly when I use PL.

I'm wondering if this is a common problem between various brands of radios, or is it just a ham rig problem? I've had my Motorola radio (MTX2000) aligned by a radio shop, so I'm doubtful the problem is on my end (it talks to other Motorola radios with no problems at all using DCS). Anyway, I'm just wondering what your recommendation would be for a repeater. Personally, I would prefer to use DCS...which I know would irk some of the hamies around here who don't even understand what PL is, nevermind the word "digital"...but intermod and what not is an issue where I'm located, so...

Thanks in advance for the input.

-Mike

Max-trac · Post by **Max-trac** » Tue Jan 25, 2005 11:49 am

I have had no problems using DPL on my Yaesu radios and Moto radios.
In fact, the PL encoders and decoders on the Yaesu Ham rigs are POOR!! Crappy waveform, falsing, slow decode etc.

DPL on them seems fine.
DPL works better (less falsing) when there is a lot of noise.

kb0nly · Post by **kb0nly** » Tue Jan 25, 2005 12:35 pm

I've never had a problem with PL on my Yaesu's, but then i don't live anywhere near a high RF environment here in the sticks! Perhaps that's what causes the falsing on them.

However, i have noticed the slow opening with the PL decode on, the radio is a FT-2800, the solution is to turn the squelch down all the way, then go in the menus and turn down the set level if you have that turned on for squelch.

Why it does it sometimes i don't know, perhaps because the signal it was receiving was marginal to begin with.

VA3XDJ · Post by **VA3XDJ** » Tue Jan 25, 2005 1:29 pm

DCS is more sensitive to noise and interference than PL and in noisy or high RF conditions it will not unmute squelch where PL would work fine.

We were testing PL vs DPL on GMRS, and any type of noise, co-channel interference or RF emitted by computers, debit machines, etc would prevent DPL from decoding its sequence where PL would work just fine.

Just my 2 cents.

bernie · Post by **bernie** » Tue Jan 25, 2005 9:27 pm

My two bits worth:

I have had much experience with both types, and I would recomend tone PL over DPL in mixed systems.
Tone also decodes faster.

Some non Motorola radios work to some degree or other on DPL, often depending on code, then some require 1KC DPL deviation to decode.

Tone PL is the industry standard and works fine.

The DPL was developed by Motorola because of problems with crowded UHF community repeater channels, as well as low band skip.

Not to mention that when sales made a DPL system sale, the low price pages dissappeared from the price book.
No one could develop a compatable system for several years.

If you have repeater receiver interference problems PL of any sort is a band aid.
Interference will manafest as erratic talk in range on your repeater.
Receiver Desensitasation.

Building repeaters is fun:
I put two MSF5000 on the air today.
Wish you luck

Post by **bradlington** » Sun Jan 30, 2005 10:52 am

There is also the setting on commercial to have std or inverted DCS.

May want to check it out.

Regards
Brad

bernie · Post by **bernie** » Mon Jan 31, 2005 11:28 am

My two bits worth:
"Inverted" DPL is to compensate for the code getting inverted some where.
An example would be changing the receiver injection from low to high side, which would invert the received code, since DPL uses true frequency shift modulatin.
In the case of after market controllers, and boards, this option allows for interfacing to what ever equipment you are working on so it responds as expected on the air.

In effect it is just another number.
The R2001 analyzers have an inverted PL/DPL option for this purpose.

EddieC · Post by **EddieC** » Mon Jan 31, 2005 1:02 pm

Yet another 2 bits thrown in:

I've had issues with Moto portables on Kenwood repeaters using PL. Some kind of incompatability that causes squelch tail. No one has complained, so I haven't really looked into it. No squelch tail on the moto repeaters.

If the repeater you want to set up is for GMRS, DPL gives you a bit of advantage because bubble pack radios generally won't do DPL.

Other than that, I stick to PL. Unless you're expecting interference from other systems, I would even skip it all together. You get a little distance advantage with CSQ.

Eddie

kcbooboo · Post by **kcbooboo** » Mon Jan 31, 2005 1:26 pm

The squelch-tail elimination method used by Motorola is slightly different from what is used by other manufacturers. They all utilize some amount of phase-shift of the PL tone, but I believe Motorola's is something like 220 degrees, where the others are around 180 degrees. Just enough difference so "crossing the streams" will work sometimes, and not others. It was probably done for patent protection purposes.

I believe there's another thread on BatLabs that goes into this in greater detail and mentions the exact values of phase-shift - I'm just going from poor memory.

Bob M.

RKG · Post by **RKG** » Mon Jan 31, 2005 1:32 pm

Even if your radio doesn't have an "inverted" software parameter, there is an inverted equivalent DPL for every non-inverted PL. See http://www.wpascanner.com/tones.htm

The only problem with the necessity of programming some radios for upright and some radioes for inverted is that you may lose the pushbutton "direct" feature.