Batboard

Heard a strange problem the other day with the Fairfax County, VA trunking system.

The normal control channel and the other 3 standby control channels had just a carrier
with a beep now and then. If you listened to any of the voice channels, they all had
what sounded like a control channel data on them. This lasted for some where around
half an hour or so.

Anyone ever heard a trunking system do this?

Jim

My two bits worth
This condition is called FailSoft.
There are several reasons that a system might go into failsoft.
There MUST be at least one Control channel, And one voice channel available or the controller will go into fail soft.
There can also be a fatal failure in the central controller, or a dead UPS.
Failsoft operation is designed to allow communications even with a dead controller
In failsoft operation the base station will be continuously keyed.
The "data" sound is the "Fail Soft Word" which unmutes the subscriber unit receiver.
Specific users are assigned to specific channels, should that channel be out of service that group of units will be out of contact.
The failsoft operation is like an open community repeater any one on the channel can communicate.

A half hour recovery is pretty good!

OK I can understand the fail soft mode. But I must have been asleep when we discussed how it
works. My understanding was that the radios defaulted to their pre set channel and functioned
in an open repeater mode like you stated. What I have failed to hear or missed in the discussion
was the issue of all the voice channels sending the fail soft word. The radios that I have that
were listening to the system went into an out of range indication.

Guess I need to go back and read the book again on just how this functions. My take is that if
the prime control channel goes dead, the radio will go to the other programmed control channels.
If the radio doesn't see any of them, it goes into an out of range indication. I believe what your
implying is that the radio has a failsoft channel programmed in that is not one of the original
control channels. The radio see's this data on the voice channel and then goes to one of the
original control channels to use that channel as a community repeater. What I am missing here
is how does it know which of the dead control channels to use? I am missing something in the
fail soft operation.

I will read the book over the weekend to re educate myself. Don't see the fail soft mode enough
to keep up on the details of it's functionality.

Jim

bernie wrote:My two bits worth
This condition is called FailSoft.
There are several reasons that a system might go into failsoft.
There MUST be at least one Control channel, And one voice channel available or the controller will go into fail soft.
There can also be a fatal failure in the central controller, or a dead UPS.
Failsoft operation is designed to allow communications even with a dead controller
In failsoft operation the base station will be continuously keyed.
The "data" sound is the "Fail Soft Word" which unmutes the subscriber unit receiver.
Specific users are assigned to specific channels, should that channel be out of service that group of units will be out of contact.
The failsoft operation is like an open community repeater any one on the channel can communicate.

A half hour recovery is pretty good!

Jim,

Bernie described Type I, you have a 4 or 6.0 Type II smartzone system, right?

CoM

My two bits worth:
Yes, the failsoft feature that I describe applies to Type 1,ll, AMSS as well as simulcast using the 6809 controller.
The last system that I installed for Motorola was in '95, a type ll, 5 site, 5 channel simulcast system. An antique today.
I still maintain a couple of "Legacy" 6809 systems.

This is how the early systems work:
The "subscriber unit", (That was the Motorola buzz word for your radio.) Has the same basic features today as the original. Many of these features were designed into the original type 1 trunking radios developed in the '70s.
The difference between type 1 & 2 is that type 1 has a low speed hand shake function which insures that the radio actually landed on the channel assigned by the controller, the base sends a code to unmute the mobile receiver, sounds like a "honk".
The intent of type ll is faster connect time, I think originally developed for the Japanese market. Type ll is also much more flexible as far as how the supervisory functions are concerned.

The Subscriber unit is programmed with some basic information.
1) System ID, 4 digits of hex. eg 0228
2) Size code eg B
3) Fleet, Sub Fleet, or Talk Group.
5) Unit ID.
6) Connect tone, like "PL", but not a standard PL tone. CT0=105.9
7) Control channels, minimum 1 (AMSS), max 4.
8)Fail soft channel. Optional (Any channel in the system)
There can be other features.

The voice channel is assigned by a 3 digit number, which corresponds to how many channels above the "Base Frequency"
US 800/900 systems base frequency are in the firmware of the system.
Non 800/900 systems require "Base frequency" for both receive and transmit.
(Dynamic Channel Assignment)

When the radio is first powered up, it scans looking for a control channel, if it cannot find one, it next goes to the assigned Fail soft channel. The beep is to inform the user that the system is in fail soft. The fail soft word, which is generated in the station causes the receiver to stop scanning, unmutes the receiver. The data word, sounds like "burble-burble" on a monitor is filtered, more or less, to remove the noise)
If there is no control channel, no failsoft channel you get "Out Of Range".

When the radio locks onto a control channel it first looks for the first two digits of the system ID, then the last two.
If the received system ID does not match the subscriber ID it goes into scan mode.

Type 1
The idle radios are all locked on the control channel listening to the "Back ground" word, which has information on all system activity. When a PTT is initiated, the subscriber requests a voice channel. The request has the Fleet, Sub fleet ID, individual ID. The controller assigns a channel pair, as a 3 digit number, keys the assigned base station, sends the "low speed" connect data, the originating radio sends a data burst informing the controller that it is indeed on the assigned channel.
The conversation continues until the last radio stays un keyed for a certain amount of time (Fade Timer) then the controller sends the disconnect code that causes the radios to go back to scan. If the system is busy, the disconnect code is sent, the next subscriber is then sent to the channel, which does not unkey. If the system is not busy, the voice channel may rotate to another channel, depending on the system.
Type two radios do not have the low speed hand shake, as the type 1 always landed on the correct channel.
Type ll does not have the fleet size limitations of type 1.

Just a thought,

Something that is overlooked. If 6809 check the CSC logs using SMT to see you did not have an illegal carrier(s) on the Control Channel. System should normally should go to another designated Control channel usuall Ch 1 to 4 on old Smartnet 6809's but on Smartzone with IR Quantars they usually only designate CH 1 & 2 and it will always try to stay on CH1 unless channels are prioritzed otherwise in the SZ System Manager. But in the old legacy AMMS it goes to the back up Control Channel Repeater which is on the same freq.
Illegal carrier is usually "on frequency interference" which the system does not recognize, ie Incorrect Connect Tone etc.