HSP3824 Datasheet, PDF (13/41 Pages) Harris Corporation – Direct Sequence Spread Spectrum Baseband Processor

HSP3824
TABLE 5. TEST MODES (Continued)
MODE DESCRIPTION TEST_CLK
TEST (7:0)
8 A/D Cal Test
Mode
A/D
CAL_CK
CRS, ED, “0”, ADCal (4:0)
9 Reserved
10 Reserved
(0Ah)
11 Reserved
12 Reserved
13 Reserved
14 Reserved
15 Reserved
Definitions
Normal - Device in the full protocol mode (Mode 3).
TXCLK - Transmit clock (PN rate).
Initial Detect - Indicates that Signal Quality 1 and 2 (SQ1
and SQ2) exceed their programmed thresholds. Signal qual-
ities are a function of phase error and correlator magnitude
outputs.
ED - energy detect indicates that the RSSI value exceeds its
programmed threshold.
CRS - indicates that a signal has been acquired (PN acquisi-
tion).
Mag - Magnitude output from the correlator.
DCLK - Data symbol clock.
FrqReg - Contents of the NCO frequency register.
Phase - phase of signal after carrier loop correction.
NCO PhaseAccumReg - Contents of the NCO phase accu-
mulation register.
LoadSQ - Strobe that samples and updates Signal Quality,
SQ1 and SQ2 values.
SQ2 - Signal Quality measure #2. Signal phase variance
after removal of data, 8 MSBs of most recent 16-bit stored
value.
RXCLK - Receive clock (RX sample clock). Nominally 22MHz.
BitSyncAccum - Real time monitor of the bit synchroniza-
tion accumulator contents, mantissa only.
SQ1 - Signal Quality measure #1. Contents of the bit sync
accumulator 8 MSBs of most recent 16-bit stored value.
A/D_Cal_ck - Clock for applying A/D calibration corrections.
ADCal - 5-bit value that drives the D/A adjusting the A/D ref-
erence.
External AGC Control
The ADC cal output (pin 26) is a binary signal that fluctuates
between logic levels as the signals in the I and Q channels
are either at full scale or not. If the input level is too high, this
output will have a higher duty cycle, and visa versa. Thus,
this signal could be integrated with an R-C filter to develop
an AGC control voltage. The AGC feedback should be
designed to drive it to 50% duty cycle. In the case that an
external AGC is in use then the ADC calibration circuit must
not be programmed for automatic level adjustment.
Power Down Modes
The power consumption modes of the HSP3824 are con-
trolled by the following control signals.
Receiver Power Enable (RX_PE,pin 33), which disables the
receiver when inactive.
Transmitter Power Enable (TX_PE, pin 2), which disables the
transmitter when inactive.
Reset (RESET, pin 28), which puts the receiver in a sleep
mode when it is asserted at least 2 MCLKs after RX_PE is
set at its inactive state. The power down mode where, both
RESET and RX_PE are used is the lowest possible power
consumption mode for the receiver. Exiting this mode
requires a maximum of 10µs before the device is back at its
operational mode.
The contents of the Configuration Registers is not effected
by any of the power down modes. The external processor
does not have access and cannot modify any of the CRs
during the power down modes. No reconfiguration is
required when returning to operational modes.
Table 6 describes the power down modes available for the
HSP3824 (V_CC = 5.0V). The table values assume that all
other inputs to the part (MCLK, SCLK, etc.) continue to run.
RX_PE
Inactive
Inactive
Inactive
Active
Active
TX_PE
Inactive
Inactive
Active
Inactive
Active
RESET
Active
Inactive
Inactive
Inactive
Active
TABLE 6. POWER DOWN MODES
POWER
(22MHz)
40mW
325mW
335mW
335mW
340mW
POWER
(44MHz)
100mW
475mW
500mW
500mW
525mW
DEVICE STATE
Both transmit and receive functions disabled. Device in sleep
mode. Control Interface is still active. Register values are main-
tained. Device will return to its active state within 10µs.
Both transmit and receive operations disabled. Device will become
in its active state within 1µs.
Receiver operations disabled. Receiver will return in its active state
within 1µs.
Transmitter operations disabled. Transmitter will return to its active
state within 2 MCLKs.
13