Special Frequency Hopping Operations - Analog Devices ADRV9001 User Manual

Reference Manual
FREQUENCY HOPPING
The ADRV9001 allows up to 3 DGPIO pins to select the Rx gain or Tx attenuation for each hopping frame from a Rx gain or Tx attenuation
table with a maximum of eight entries. The GPIO pins formulate an index to the defined Rx gain or Tx attenuation table and the GPIO pins are
sampled at the hop edge. Then, the corresponding Rx gain index or Tx attenuation values are applied to the corresponding upcoming hopping
frames.
ORx Gain Control
The ORx gain operates in manual gain control. In this mode, set the desired starting gain index before enabling ORx. Update the gain
throughout the ORx frame by calling adi_adrv9001_ORx_Gain_Set() API.

SPECIAL FREQUENCY HOPPING OPERATIONS

Port-Based Frequency Hopping
As noted previously, all four channel ports (Rx1, Rx2, Tx1, Tx2) can be used in FH. However, these ports are not indicated in the hopping
tables. Instead, the channel enable pins are repurposed as channel setup pins to select the channels to hop upon. In the dual hop LO Retune
mode, there are also two hop signals to indicate when new frames start, one for each LO.
Each port is also assigned a controlling LO, which is fully configurable in certain FH modes. For example, LO1 controls channel 1 ports
(Rx1/Tx1) and LO2 controls channel 2 ports (Rx2/Tx2), or LO1 controls both receive ports (Rx1/Rx2) and LO2 controls both transmit ports
(Tx1/Tx2), or LO1 controls any other combination such as Rx1 and LO2 controls Rx2, Tx1 and Tx2.
Configure the LO assignment for each in the adi_adrv9001_FhCfg_t structure. In this structure, there are fields for the Rx ports (rxPortHopSig-
nals) and the Tx ports (txPortHopSignals). In these fields, each port can be assigned a "HOP" signal, where hop signal 1 is for LO1 and hop
signal 2 is for LO2.
NCO-Only Frequency Hopping
The ADRV9001 provides a numerically-controlled oscillator (NCO)-only mode, which is only used for Rx FH. By enabling this feature, it is
possible to define a non-zero rx1OffsetFrequencyHz or rx2OffsetFrequencyHz in the hopping table and those frequencies are applied to the
NCO only. It adds an offset to the current LO frequency. Note that IF operation is supported in the regular Rx FH mode. The IF frequencies
are also defined using rx1OffsetFrequencyHz and rx2OffsetFrequencyHz. The difference is that in the regular mode, both the LO and NCO
frequencies are changed, while in the NCO-only mode, only the NCO frequencies are changed but LO frequencies are not affected. This is the
fundamental difference between the regular Rx FH mode and NCO-only Rx FH mode.
The NCO-only mode changes the NCO frequency at the beginning of each hop frame based on the hopping table entry it is using. Also, the
NCO-only mode can be utilized to perform frequency changes or "hops" anytime within a hop frame by using a GPIO pin. To use this feature,
assign a GPIO to trigger the NCO change. Update the desired Rx frequency offset using adi_adrv9001_fh_RxOffsetFrequency_Set() API at
any point, but it does not take effect until the NCO change pin is toggled (both rising and falling edges). When the GPIO pin is toggled, the
offset frequency set through the API is used and the original offset frequency defined in the hopping table is ignored. At the start of the next
frame, the NCO frequency is first obtained from the hopping table until the NCO change pin is toggled.
Figure 125 shows a timing diagram for an NCO-only example. This timing diagram examines the actual RF frequency of the Rx1 port. For
simplicity, all frames are for Rx1. This figure shows two frames: "n" and "n+1". The first point to note here is that the carrier frequency for each
frame is taken from the FH table and does not change during the frame. The dynamic elements of the diagram are the Rx1 offset frequency,
the NCO 1 change pin, and the Rx1 output frequency. Throughout the frames, the BBIC loads new values for the Rx1 offset frequency. The first
offset frequency is retrieved from the hopping table. It adds an offset to the Rx1 output frequency, which does not change until the NCO 1 pin
is toggled. When the NCO 1 change pin is toggled, the offset frequency is updated based on the value set through the API, and thus the Rx1
output frequency is shifted correspondingly.
Table 54. Simplified Hop Table for NCO-Only Hop Example
Index
n
n+1
analog.com
Carrier Frequency (MHz)
500
600
ADRV9001
Rx1 Offset Frequency (kHz)
500
500
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