Analog Devices ADRV9001 User Manual page 64

UG-1828
Set enableRiseToOnDelay equal to the propagationDelay or enableRiseToAnalogOnDelay + enableSetupDelay. The transmit enable
rising edge should occur enableRiseToOnDelay before on air transmit begins. The transmit interface could be set high at the same time
as transmit enable to start transmitting guard symbols.
When the frame ends, the transmit enable falling edge should ideally occur right as the last valid data that must be demodulated by a
receiver sent over interface. Interface can be held on for some time longer to allow guard data to be sent across by setting
enableHoldDelay to a value greater than zero (note currently enableHoldDelay is forced to 0 by ADRV9001). The parameter,
enableFallToOffDelay, determines how much after the transmit enable falling edge, the antenna is switched away from the transmitter
channel. It must always be set to a value greater than equal to enableHoldDelay. If both values are set equal, for example, both are set to
0, the interface turns off first then analog powers down. To ensure that all the data that was sent over the interface makes it onto the air,
enableFallToOffDelay should be set greater than or equal to
enableHoldDelay + propagationDelay
If it is greater, then zeros are transmitted after all the data sent over the interface has been propagated.
Use Case 2: t < t
TxPD TxEnaSetup
In this case, as shown in Figure 55, the time taken for data to propagate from the digital interface to antenna is very small, that is, t
smaller than the time to setup the analog front end t
power up begins immediately after TX_ENABLE rising edge. The parameter, enableRiseToOnDelay, could also be set to 0, in this case,
the antenna is switched to a transmit channel, as soon as analog power up completes. For a more deterministic delay between transmit
enable rising edge and antenna switch time, enableRiseToOnDelay should be set to a value greater than or equal to
enableRiseToAnalogOnDelay + enableSetupDelay
In such a case, after raising Tx_enable, some guard data must be sent over the interface to make sure all valid Tx data is transmitted on
air. Based on the length of the user guard time and Tx timing parameter configurations, only a part or none of the guard data is
transmitted to the air.
When the frame ends, enableFallToOffDelay could be set in a similar way as discussed in Use Case 1.
Note ADRV9001 currently is not controlling the antenna switch, therefore it is the user's responsibility to switch the antenna on and off
at the accurate time. As a recommendation, the antenna should be switched on after analog power up and switched off before analog
power down.
FRAMING ON AIR
FRAMING AT BBIC
PIN: TX_ENABLE
TX_INTERFACE
TX ANALOG POWER
TX ON: ANTENNA SWITCH
USER PROVIDES ADRV9001
ADRV9001 PROVIDES USER
HELPER PARAMETERS
Receive Timing Definition
Receive timing parameters define the events that take place in order from the start of reception at the air to the end of reception when the
receive burst is sent through the ADRV9001 data port to the BBIC.
, in such a case, enableRiseToAnalogOnDelay can be set to 0, so that analog
TxEnaSetup
t
TxPD
t
TxGT
t
TxEnaSetup
t
TxEnaRise2On
t
TxEnaRise2AnaOn
Figure 55. Transmit Timing Parameters (t
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Preliminary Technical Data
VALID DATA
VALID DATA
t
TxEnaHold
t
TxEnaFall2Off
=0
< t )
TxPD TxEnaSetup
t
TxPD
t
TxPD
is
TxPD