Binary logic error within the 16 bit TGID field

Hamilton County TRS (APCO-P25 9600 baud)

System Type: Project 25 Standard

System Voice: APCO-25 Common Air Interface Exclusive

The Digital Scanner Team located in Hamilton County, Ohio.

Has observed a problem with some Radio Shack PRO-96 &

PRO-2096 Radios.

That I first called "Closed Mode MOT: bleed over".

When the Banks are set up in the "Closed Mode".

The problem is receiving transmissions of talkgoups that

haven't been programmed in the Radio's ID list.

The Radio will display the MOT: ID #.

Also if you lockout this MOT: ID # that was displayed, the

Radio will lockout a different talkgroup that is stored in the

Radio's ID list.

Example # 1:

Bank 01 is set up in the “Closed Mode” to only receive the

transmissions of the Hamilton County Police.

Talkgroup # 00051 is programed in the Radio's ID list with the

alpha tag of LE EAST DISP.

When you receive Hamilton County East Dispatch transmission

the Radio will Display the associated alpha tag LE EAST DISP.

Then you receive the transmission of Cincinnati Police Dist. 2

This talkgroup HAS NOT BEEN programed in the Radio's ID list!

MOT: 32819 will show on the Radios display & you hear the transmission.

If you press L/OUT the Radio will lock out # 00051 alpha tag LE EAST DISP.

The reverse action will occur in Bank 04 that is set up in “Closed Mode”

for Cincinnati Police. MOT: 00051 will show on the Radios display and

you hear the transmission. If you press L/OUT the Radio will lock out

talkgroup 32819 DIST 2 Disp.

Example # 2:

Bank 01 is set up in the “Closed Mode” to only receive the transmissions of the

Hamilton County Police.

You have programed in # 00081 & the alpha tag AW 19

When you receive a encrypted transmission.

MOT: 32849 will show on the Radios display {This is Cincinnati PD C2C 1}

If you press L/OUT the Radio will lock out # 00081 & the alpha tag AW 19

Consistently the same talkgroup ID will be locked out when the Radio

receive the transmission the opposing talkgroup!

What we have discovered is within the Talkgroup ID 16 bit TGID field.

That some Radio Shack PRO-96 & PRO -2096 Radios are neglecting

the high bit. When the Radios are receiving transmissions of talkgoups

there could be a translation table error at bit 0x8000 within the 16 bit TGID field.

The Hamilton County / Cincinnati TRS system has 105 talkgroups

that with the exception of bit 0x8000, that are "IDENTICAL".

Here is a example of 10 talkgroups:

TGID TGID TGID

Digital 16 bit field Alpha Tag

00001 0000 0000 0000 0001 FD DISP 1

32769 1000 0000 0000 0001 MAIN AUX

00051 0000 0000 0011 0011 LE EAST DISP

32819 1000 0000 0011 0011 C PD DIST 2

00052 0000 0000 0011 0100 LE WEST DISP

32820 1000 0000 0011 0100 C PD DIST 3

00053 0000 0000 0011 0101 LE CENT DISP

32821 1000 0000 0011 0101 C PD DIST 4

00054 0000 0000 0011 0110 LE SPARE

32822 1000 0000 0011 0110 C PD DIST 5

00395 0000 0001 1000 1011 JAIL 3

33163 1000 0001 1000 1011 SPARE 11

All Radio Shack PRO-96 & PRO -2096 Scanners here in Hamilton County, Ohio

are not effected which leads us believe that the problem is not in the firmware.

We have confirmed this problem with CPU: 1.1 , 1.3 & 1.4

Our goal is to bring this problem to the attention of GRE & Radio Shack.

We would like to know with this information is there a way that you can

bench test the binary logic translation table and detect the error at

bit 0x8000 within the 16 bit TGID field.

Thanks

royalzapper

Billy Zapf

“MOT: Closed Mode leak”?

As I think about the problem more the Radio can differentiate

the difference of the high bit.

The Radio can recognize the bit 0x8000 because the opposing talkgroup

MOT: that shows in the display is the proper digital ID number.

Plus the right transmissions are always hear on the proper associated

digital ID number.

The problem is with what I first called the “Closed Mode MOT: bleed over”.

Maybe I should have called “MOT: Closed Mode leak”?

Perhaps something within the binary logic that should prevent talkgroups

from passing through the "Closed Mode" translation table?

What I have observed is ONLY the opposing talkgroups are passing through

the Banks that are set up in "Closed Mode".

No other MOT: ID # has passed through or been displayed.

I do not know how the Radios logic circuit works. I am only trying

to give the information the best that I can. With the hope that this

may assist in finding a way to resolve this problem.

Thanks

royalzapper

Billy Zapf

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