Configure phase modulation (CFGPHZ)

CFGPHZ configures RVP10 phase control output lines, which determine the relative phase of each transmitted pulse.

In some cases the chosen phase sequence has side effects elsewhere in the processor, for example, different algorithms may be used in Random Phase mode according to the transmit sequence that is requested.

Some phase sequences chosen by CFGPHZ also expect additional arguments to have been supplied by the XARGS command.

Phase sequences are expressed as a list of N 16-bit binary angles representing the desired phase sequence. The sequence is assumed to be periodic with period N.

The Mz command defines the correspondence between phase codes and phase angles.

 15  14  13  12  11  10   9   8   7   6   5   4   3   2   1   0
---------------------------------------------------------------
|   |   |   |   |   |   |   |   |    |   |   |   |   |   |   |   |
|   |  PhSeq    | 0   0   0   1    0   0   0   1   1   1   1   1 |  Command 
|---|-----------|------------------------------------------------|  

PhSeq=0

Selects No Modulation. RVP10 outputs a constant default phase request as defined in the Mz menu.

PhSeq=1

Selects a Random Phase sequence. This is also the default phase modulation that is output following power-up. From the set of valid phase codes that are defined in the Mz setup section, a random code is automatically chosen for each pulse. Each code has an equal probability of being chosen each time, and the choice is independent of any previous state. No XARGS words accompany this command.

PhSeq=2

Selects a User Defined sequence. If no XARGS have been supplied, RVP10 outputs the default idle phase that is defined in Mz. If XARGS are supplied, then they are interpreted as a sequence of 16-bit binary angles.

RVP10 makes the best match between each desired angle and the closest realizable angle that the phase modulation hardware can produce. The maximum length of the sequence is 1024 pulses.

PhSeq=3

Selects the SZ(8/64) sequence.

This is a systematic code¹ that separates and recovers first and second trip echoes in Random Phase mode. It usually performs better than a truly random transmit sequence, especially when the processing interval is fairly short (as little as 32-pulses).

With no XARGS, RVP10 automatically generates the phase sequence using the closest realizable angles that the phase modulation hardware can produce. This is the recommended way to invoke SZ(8/64) coding. You may also supply your own 32-pulse angle sequence.