GC5018 Datasheet, PDF (7/115 Pages) Texas Instruments – 8-CHANNEL WIDEBAND RECEIVER

www.ti.com
GC5018
8-CHANNEL WIDEBAND RECEIVER
SLWS169 – MAY 2005
16
I
16
Q
32
33
58−bit
Integrator
32
clear
58−bit
Register
transfer
9−bit
sync
sync delay
counter
21−bit
interval
counter
21−bit
integration
counter
9
21
21
delay
(in 8 sample
increments)
interval
(in 8 sample
increments)
integration
(in 8 sample
increments)
RMS power
sync
delay
integration time
integration time
integration time
interval time
sync integration
event
start
integration
start
integration
start
Power is calculated by squaring each 18 bit I (I and Q for complex inputs) sample, summing, and then
integrating the summed-squared results into a 58 bit accumulator over a programmable integration period.
The integration period is programmed into the 21 bit counter, in 8 sample increments. The power read is:
power = [ (I²) x (Xx8 + 1) ] for real inputs where X is the integration count.
power = [ (I² + Q²)x (Xx8 + 1) ] for complex inputs where X is the integration count.
A programmable 21 bit interval counter sets the power measurement interval (how often power will be
measured) in 8 sample increments. A measurement integration period is started at the beginning of each
interval period.
The process begins with a sync event starting the 9 bit delay counter. After (8xsync_delay + 2) samples,
the integration interval is started. Integration continues until the integration count is met, at which point the
58 bit integrator results are transferred to the read only register and an interrupt is generated. A new
measurement period will start at the end of the interval period.
NOTE
Each of the four composite RMS power meter blocks has its own delay sync, interval, and
integration period counters, as well as separate sync source registers.
The 21-bit counters in 8 sample increments allow up to 104.8mS interval times at 160MHz clock.
RECEIVE DIGITAL SIGNAL PROCESSING
7