Functional Descriptions ......
Figure 11 (below) shows, in diagrammatic form, the sequence of tones for an Over-Air
Re-Configuration of the Tx Address between the controlling base station and the CM1481.
Example
Over-Air
Transactions
Figure 13 shows the complete range of tone sequences to be used with the CM1481. For
Over-Air transactions follow the steps illustrated in Figure 11 substituting the required
action in STEP 1 with the required request and confirmation from Figure 13. Note the use
of the Data Prefix tone “B” in the data field; all operations must conform to the HSC
Operational Rules which are described on the following pages.
STEP 1
Over-Air Re-Configuration Request (Tx Address)
Rx Address Tones
-
from base
New Tx Address Tones
+ Data Prefix
4
0
B
B
B
Data
Prefix
Tone 1 Tone 2 Tone 3 Tone 4 Tone 5
Tone 1 Tone 2
Tone 3 Tone 4 Tone 5
STEP 2
STEP 3
STEP 4
Security Check (SEED)
Old Tx Address Tones
-
from CM1481
SEED Tones
s1, s2, s3
s1
s3
2
s2
Security Reply (KEY)
Rx Address Tones
-
-
from base
KEY Tones
k1, k2, k3
k1
from CM1481
k3
3
k2
B
Configuration Confirm
New Tx Address Tones
8
B
Fig.11 Example Over-Air Re-Configuration Tone Transaction
The figure below shows the pseudo-random number generation in diagrammatic form.
The base unit controller's software and circuitry will require to emulate this function.
Pseudo-
Random
Number
The SEED is a random 8-bit number produced by the CM1481. The SEED is loaded into
the register and shifted right by the amount of steps configured as: Pseudo Iterations.
Note the Exclusive-OR functions.
Information
The result is the KEY.
s1/k1
s2/k2
s3/k3
Parallel "SEED"
/
Parallel "KEY"
7
MSB
6
5
4
3
2
1
0 LSB
Feedback
Ex-OR
Register Shifted Right 1 Step per Configured Iteration-Step
Fig.12 An 8-Stage Pseudo-Random Counter Employing Exclusive-OR Feedback
19
CMLMICRO [ CML MICROCIRCUITS ]
