Page 42 - EngineerIT November 2021

RADIO COMMUNICATION

full lock of PLL before dwell time starts. When selecting the loop filter
bandwidth, users should also evaluate the phase noise performance
required in their applications.

Static and dynamic table load up to 128 different frequency entries
2
The ADRV9002 utilises a hop table concept for all modes of FH.
A hop table contains a list of frequencies and other operation
parameters for each hop frame. A hop table can be static, meaning it
is loaded during the initialisation and not allowed to change on-the-
fly. It can also be dynamic, which means it is loaded while performing
the hopping; in such a case, the user can change the table content
on-the-fly. A similar concept of ping pong is employed so that the
user can optionally load two different tables, each with a minimum
of 1 to a maximum of 64 entries. While one table is being used for
the current hop frame, the other table is being loaded to prepare
for the next hop frame. Each entry notifies the ADRV9002 of the
configurations for a certain hop frame. A hop table can be indexed by
either incrementing the index automatically (start from the first entry
of the first table to the last entry of the second table and then go
back to the first entry of the first table again with two hop tables, or Figure 7: ADRV9002 hop tables content and the indexing method.
loop continuously with one hop table) or accessing a specific entry at
any time indicated through digital GPIOs. Before further discussing the hop table operation in FH, it is
Figure 7 shows hop table A and B, each with N entries (1 ≤ N worthwhile to understand the high-level communication between the
≤ 64). Each entry in the table includes four key parameters: hop ADRV9002 and the baseband integrated circuit (BBIC).
frequency, intermediate frequency (for receive IF mode only), As shown in Figure 8, BBIC acts as the main for FH operation, which
receive gain index and transmit attenuation. In a TDD operation, sets up FH mode, the channel setup signals (Rx1_ENBALE, Rx2_ENABLE,
users must notify the ADRV9002 which channel (either transmit or Tx1_ENABLE, and Tx2_ENABLE), the HOP signals (HOP1 and HOP2), and
receive) is enabled for each hop frame by using a dedicated channel the static or dynamic hop tables (hop frequency, receive IF frequency,
setup signal (one for each transmit channel and one for each receive gain, and transmit attenuation). BBIC communicates with the
receive channel). Therefore, although each entry in the hop table ADRV9002 through an SPI interface or DGPIOs. The ADRV9002 acts as
contains parameters for both receive and transmit, only the relevant the node for FH by accepting the signals from BBIC and then configures
parameters are utilised. the data path and LOs accordingly.

Figure 8: A high-level block diagram of communication between the ADRV9002 and BBIC during frequency hopping.

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