Conventions/Limits for Radios (from RPM Help Screens)
The below is taken directly from the HELP SCREEN section in the RPM software.
...A very underused resource!
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Conventions/Limits for Radios
Radio Programming – Systems/Groups/Channels
The following topics discuss the conventions and limits for programming in the all radios programmed using RPM. It covers the limits and some of the options a user has when creating personalities for these radios.
Unique Alpha Names
Limit = 1024 unique alpha names for – Groups, Systems, RF Channel frequencies.
These limits are imposed by the size of the pointers into reference tables in the personality.
However, this does not mean that you are limited to 1024 groups or 1024 channels in a radio personality. The limits are much higher – see below.
Trunked Talk Groups
In EDACS, there are 2048 GID (group ID) numbers. In P25 trunking or EDACS-IP (Extended Addressing) there are 64K valid group numbers available.
In the radio, you are limited to 512 systems and each system is limited to 1024 groups. So the theoretical limit is 524288 groups. RPM actually further limits you to 13,824 groups. Memory space will limit you to less than this total – see below.
Since the radio is limited to 1024 unique alpha names, how do you program more than 1024 groups?
You can actually repeatedly re-use these 1024 alpha names with different GID numbers as long as they are used in different systems. In this manner, you can actually have many more than 1024 groups in a personality.
Example: Group name "TAC-1" can be assigned to GID 1237 in system-1 and the same name "TAC-1" can be assigned to GID 1439 in system-2.
So with R13 or later a radio personality can contain 1024 or more groups. But only 1024 can have unique alpha names.
Trunked System-Groups
The number of allowable Trunked "system-groups" is set by the feature encryption of the radio. Commonly used values for this number are 128 or 800.
Conventional channels/systems are not counted here. System-groups refer strictly to the number of Trunked systems and groups.
To calculate the number of system-groups used in a radio personality: add the number of groups in system-1, plus the number of groups in system-2, plus the number of groups in system-3, etc. until you have added all the systems then add the number of systems.
Example: you have a radio with a total of 5 systems - 4 systems each with 10 groups and 1 system with 6 groups.
System-groups = 10 grp + 10 grp + 10 grp + 10 grp + 6 grp + 5 sys = 51
Note that a tab in the RPM software called "Synopsis" shows a summary of information for a personality file, including number of System-Groups and % of available personality memory space that has been used.
System-Groups are limited by personality memory size
P5100 is only allowed to have 128 system-groups. This number is not expandable. All of the other radios by default are set to 128 system-groups. This number is expandable with a feature-encrypted software option.
If you buy the option for "max System-Groups" then you are not really limited to 800 sys-groups. The number of allowed "System-Groups" is set to 65,535. The limiting factor is how many system-groups will fit in the available personality memory space.
How many systems and groups will fit varies depending on many parameters, but it is usually in excess of 5000 system-groups.
Example: If you have fewer group-sets and just reuse the same group-sets in each system, then you will be able to fit more systems. If each system has 64 unique groups, then you will be able to fit fewer systems.
Another cause of variability: phone lists, I-call (select-call) lists, and scan lists also take up memory space.
Number of Systems
The number of allowed systems in the radio is limited by another feature encryption number called "number of systems". This number is set to 512.
This number corresponds to the limit of 512 unique alpha-names for systems.
However, the number of systems that will fit in a given radio personality may be less than 512 if each system takes up lots of the available personality memory. Systems with more groups take up more room – as described in the prior section.
Conventional Channels
The number of allowed programmable conventional channels is limited by a separate feature encryption number called "number of conventional channels".
This number is set to 65,535.
However, other factors limit the number to less than that:
• There is a limit of 1024 unique RF channel frequencies.
• There is a limit of 1024 unique alpha names
• Since there is a limit of 1000 channels per system, the overall limit of conventional channels is also controlled by number of systems (512) allowed
The final limiting factor is the personality memory size.
In other words, 512 systems max x 1000 channels per system max = 512000 theoretical limit. RPM software further limits this to 13,824 possible channels.
Just like in trunking groups, you can re-use the 1024 frequencies and the 1024 names differently in each system. In this manner, you can easily exceed the 1000 available channels that some other radios claim.
Example: In a radio in system-1 you can have a channel called "Police-North" at freq. 156.000MHz. In system-2 you could have another channel called "Police-North" that is a different frequency. In system-2, you could also re-use the previous 156.0000MHz frequency and call it another name "Police-South".
So while the P5100 radio is limited to 128 system-groups (Trunked), it can still have >255 conventional channels.
Feature Encryption Status
The RPM software has no awareness of the Feature-Encryption status of the radio. So even if your radio is limited by feature-encryption to 128 sys-groups, the RPM will let you create a personality with 150 system-groups. However, when you load this personality in the radio and turn the radio on, the radio will give you an error message "Inv Sys" or "Sys/Grp above 128".
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