DRS WJ-8611, Инструкция по установке, эксплуатации и обслуживанию

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WJ-8611 DIGITAL VHF/UHF RECEIVER
INSTALLATION 2-13
Note that the above rates are for I/Q pairs, and not the individual data word
strobe rate. There are two data words for each I/Q pair.
Figure 2-5
illustrates the timing for transfer of individual I and Q data words. The
positive phase of the differential signals is shown. The data and control
signals change on the negative edge of the clock which places the clock
rising edge at mid-bit of the data. Note that the strobe occurs one cycle
before the data word starts. The 10 MHz clock signal is always present.
20 CLOCK CYCLES
16 CLOCK CYCLE FOR DATA
I WORD
I/Q*
DATA
STB
10 MHz CLOCK
20 CLOCK CYCLES (2
µ
s)
D15 D14 D13. . . D1 D0
4 'empty' CLOCK CYCLES
D15 D14. . .
Q WORD
98-0327
Figure 2-5. Timing Diagram for I/Q Data Transfers at the DIGITAL IF OUT Connector
Figure 2-6 illustrates two examples of the strobe over a longer period of
time (several I/Q pair transfers). The first line shows the strobe at the
250 ksps pair rate (2
µ
s period) used for bandwidths 30 kHz and greater.
The second line shows the strobe for the 62.5 ksps pair rate (16
µ
s period).
Note that the strobes for a single I/Q pair are always 20 clocks or 2
µ
s
apart. For the 250 ksps I/Q pair rate example, the strobe appears to have a
500 kHz rate because of the 2:1 ratio between the I/Q pair period
(1/250 ksps = 4
µ
s) and the 2
µ
s between I and Q strobes. For the lower
data rates, there is a gap between the I/Q pairs as shown in 62.5 ksps pair
rate example. The lower data rates are similar to the 62.5 ksps case, with
periods equal to the inverse of the specific rate.
Courtesy of http://BlackRadios.terryo.org