1996 Oct 31
13
Philips Semiconductors
Objective specification
DECT burst mode controller
PCD5041
6.5.3
S
EAMLESS HANDOVER
Seamless handover guarantees that when speech
information is switched from one slot to another, no speech
samples are lost, added or displaced. Seamless handover
is achieved in the RF interface by:
Using a look-up table containing the correct start
addresses of the B-fields in the data memory
The RF receive and transmit blocks move data to/from
the data memory block in 4-bit nibbles.
6.5.4
RF
CONTROL SIGNALS
The timing of the control signals to the RF section is fixed,
but such that an RF delay between 1.5 and 7
μ
s can be
tolerated. Only the transmitter ramp signal and the
synthesizer enable are programmable within certain limits.
6.5.5
SYNTHESIZER PROGRAMMING
To program a synthesizer, a 3-wire serial interface is used.
The signals on this interface are:
S_ENABLE (enable)
S_CLK (clock)
S_DATA (data).
To program various types of synthesizers, a 3-byte shift
register is present. Three data formats are supported:
8, 16 or 24 bit words can be selected. The transfer of data
from a frequency table in the common data memory to the
shift register is under control of the PCC.
6.5.6
RSSI
MEASUREMENT
(see Fig.8)
The RSSI measurement in the PCD5041 RF-interface
block is done in 3 parts: a peak/hold detector, a 6-bit A/D
converter, and an RSSI control unit, which controls the
peak/hold detector and the A/D converter. Once per slot
time, a sample is fetched by the PCC and saved in the
appropriate area of the common data memory.
If the radio receiver is active in a particular time slot, the
RSSI value will automatically be measured in that slot.
Adjustment to the RSSI_AN input level can be made with
VREF.
Fig.8 RSSI measurement path.
handbook, full pagewidth
MBH711
RSSI
PROCESSING
(SW in PCC)
internal
bus
write in memory
RSSI
CTRL
(HW)
6-BIT
A/D
PEAK
HOLD
RSSI value
filtered width
= 30
μ
s
(
τ
=10 to 40
μ
s)
6
RSSI_AN
RF-INTERFACE
RSSI_AN
VREF
RSSI_CTR
start_AD