Specifications

Programming Guide 3-15
ESG Family Signal Generators Remote Data Transfer
User File Data Downloads
NOTE The data in pattern RAM is static. Firmware writes to PRAM once for the
configuration selected and the hardware reads this data repeatedly.
Firmware overwrites the volatile PRAM memory to reflect the desired
configuration only when the data source or mode (digital communications
format) is changed.
Take for example, transmitting a 228-bit user file for timeslot #1 (TS1) in a normal GSM
transmission. Per the standard, a GSM normal channel is 156.25-bits long, with two 57-bit
data fields (114 bits total per timeslot), and 42 bits for controlling or signalling purposes.
NOTE Compliant with the GSM standard, which specifies 156.25-bit timeslots, the
signal generator uses 156-bit timeslots and adds an extra guard bit every
fourth timeslot.
The seven remaining timeslots in the GSM frame are off. The user file will completely fill
timeslot #1 in two consecutive frames, and will then repeat. See Figure3-2.
Figure 3-2 Mapping User File Data to a Single Timeslot
For this protocol configuration, the signal generator’s firmware loads pattern RAM with
the bits defined in the following table.
Table 3-1 PRAM Bit Definitions for GSM Normal Channel Transmission with
a User File Data Source
Frame Timeslot PRAM
Address
Data Bits Burst Bits Pattern
Reset Bit
1 0 0 -155
0/1 (don’t care)
0 (off) 0 (off)
1 1 (on) 156 - 311
42 bits set by GSM standard &
first 114 bits of user file
1 (on) 0
1 2 312 - 467
0/1 (don’t care)
00
1 3 468 - 624
0/1 (don’t care)
00
1 4 625 - 780
0/1 (don’t care)
00