Dumb question. Why always 16 Channels on portables?

nmfire10 · Post by **nmfire10** » Thu Nov 27, 2003 3:02 pm

I know this really has nothing to do with anything in peticular but I started wondering about this while working on some upgraded programming lists.

Why is it that almost all portables radios are limited to 16 channels, either all together or per zone/bank. Obviously, the full display and keypad models set aside... Why is 16 the magic number for all the manufacturers?

commtek · Post by **commtek** » Thu Nov 27, 2003 3:16 pm

Can't answer where the 16 number came from, but I suspect it had something to do with the availability of binary coded decimal switches which were widely used in the day....

Now, with the radios being more computer-like and using a simple up/down pulse to the micro, I suspect that the old convention is carried over.

BTW- the Kenwood 80 and 90 series is unlimited channels per group if you make the rotary control on top the zone select function. Works great, this is how we set all of them up.

nmfire10 · Post by **nmfire10** » Thu Nov 27, 2003 5:39 pm

I don't get it. How are you making the 90's unlimited channels?? I wash I had more than 16 and that is what we use.

RKG · Post by **RKG** » Thu Nov 27, 2003 5:43 pm

In most cases, I believe it goes back to the use of four data lines to binary code channel selection. 4 bits equals 16 possible values.

mancow · Post by **mancow** » Thu Nov 27, 2003 5:50 pm

Bendix King always had just 14 channels. If you took the knob off the encoder was still 16 but slot 15 and 16 would select channel 1 and 2 respectively. That seemed odd to me.

I guess the new GPH series are 16. I suspect it's like he said, it's the binary encoders. Plus, how would you label anything more than 16? There wouldn't be much room. It would be too small of a movement to handle reliably in the field.

mancow

commtek · Post by **commtek** » Thu Nov 27, 2003 5:51 pm

Make the top 16 position switch the group select and the two buttons in front of the toggle switch the channel up and channel down....

This way, you can have up to the 160 channels in one group if you want..

DAL-COM · Post by **DAL-COM** » Thu Nov 27, 2003 9:01 pm

I have to add that the Vertex 800 and 900 portables can also do this, thereby giving you 512 channels.
The Icom F30 also can do it giving you 250 channels.
16 channels might be inadequate for interoperability. Sounds like a grant application..........

Jim202 · Post by **Jim202** » Fri Nov 28, 2003 6:31 am

Another point to ponder is ther memory size that was available. I have seen some 8 channel radios hacked to 16. Afetr that you run out of memory in the radio.

Second point to ponder is the scan ability. Even at 16 channels, the scan time can effect the ability to receive messages. I have seen some people mode the GE radios with a second EEPROM and go to 32 channels. Those radios seem to never shut up. They also missed a portion of a transmission because of the long time it takes to run through all 32 channels.

The 16 channels per group seems to be a good balance between scan time and how much of a transmission you miss from the scan time.

Jim

nmfire10 · Post by **nmfire10** » Fri Nov 28, 2003 4:39 pm

commtek wrote:Make the top 16 position switch the group select and the two buttons in front of the toggle switch the channel up and channel down....

This way, you can have up to the 160 channels in one group if you want..

So if I only need one group, what would position 2-16 do??

This would be ideal for personal use but I don't know if I would want those little buttons for changing channels on a fireground. If you need to get to channel in an emergency, it is not going to happen with those tiny buttons.

commtek · Post by **commtek** » Fri Nov 28, 2003 9:11 pm

Matt-

I don't know how many channels you want in your groups, but my personal 90 that I use for EMS has about 20 channels in group 1. I have 6 other groups set up also with varying numbers of channels. I would personally not set up a group with more than 32 channels, as it takes too long to shuffle through them. I generally set these radios up for customers such that if they work for more than one agency, I make a group with all the channels they would need for that agency. Then I make groups for all the other "nice to have" channels.

The little buttons to change channels might be more difficult to operate with fire gloves on, but honestly, how many times do you change channels once you are operating on the fireground.

Seems to work well around here....

nmfire10 · Post by **nmfire10** » Fri Nov 28, 2003 9:17 pm

Well, the common NFPA complient repeater setup out here now has the following:

Repeater
Talk-Around of the repeater
At least 2 Simplex tactical channels.

Going back and fourth would be a major pain. But it is nice to know the ability is there.

AngelFire_91 · Post by **AngelFire_91** » Mon Dec 01, 2003 10:43 am

Here is something I've always woundered. In the new astro portables, XTS in particular, why is it made where only 15 talkgroups can be put into a personality when there are 16 channels to a zone, if you have it set up that way. You have to make 2 personalities for every 16 channels giving you want the same personality throughout those 16 channels. what? does that make since?? Not to me anyway.

Post by **wavetar** » Mon Dec 01, 2003 5:32 pm

AngelFire_91 wrote:Here is something I've always woundered. In the new astro portables, XTS in particular, why is it made where only 15 talkgroups can be put into a personality when there are 16 channels to a zone, if you have it set up that way. You have to make 2 personalities for every 16 channels giving you want the same personality throughout those 16 channels. what? does that make since?? Not to me anyway.

Actually, it's that way for any of the trunked radios that use the Personality/Zone-Channel Assignment method (MTS2000/MTX8000/VisarPP/MCS2000/AstroSpectra/ASI/II/III, etc), not just the XTS. I've often wondered the same thing. I assume it makes sense to the Moto engineers somehow.

Todd

nmfire10 · Post by **nmfire10** » Mon Dec 01, 2003 5:38 pm

wavetar wrote:
AngelFire_91 wrote: I assume it makes sense to the Moto engineers somehow.

Yea, just like the volume knob on the Minitor III & IV make sense to them somehow.

RKG · Post by **RKG** » Thu Dec 04, 2003 9:14 pm

Could it be that the 16th "slot" is reserved for ATG (whether or not used)? Just a guess.

Post by **wavetar** » Fri Dec 05, 2003 4:13 am

RKG wrote:Could it be that the 16th "slot" is reserved for ATG (whether or not used)? Just a guess.

You could be right, I never thought of that.

2wayfreq · Post by **2wayfreq** » Fri Dec 05, 2003 9:53 am

I noticed on the astro that there are 15 scan positions in each zone. So, I made scan channel 1-->personality 2 Scan channel 2--personality 3..etc etc. Kindof a workaround, but I have to be on channel 1 to scan all in each zone.