Tell the channelizer to measure new total-power zero-offsets.

Arguments:

Receivers receivers

The set of receivers to target.

Bands bands

The set of frequency bands to target.

Example 1:

The following example asks the channelizer task to find the total-power offsets of all correlator channels. This process takes a couple of integrations to complete, so in the example, the acquired function is used to wait for it to complete (or fail).

 tpzero all, all
 until $acquired(channels)

Context:

The CBI has 13 receivers (rx0..rx12) who's 10GHz bandpasses are split into 10 bands (band0..band9) by a channelizer. The resulting 130 signal paths are refered to as channels. The corresponding correlators contain total power detectors that produce voltage outputs that reflect their input powers. The tpzero measures the zero offsets of these detector outputs by turning off the IF amplifiers that feed the correlator inputs for a full integration, then measuring the resulting total power outputs in volts. These numbers are recorded in the archive and are used by the channelizer task when asked to set the total power correlator inputs to a specified level. Since the process takes a couple of integrations to complete the control program is notified on completion and the $acquired(tp) then returns true.

Note that if any command that involves the channelizer, such as the channel, attenuate, channelizer, tp or another tpzero command, is initiated before a previous tpzero (or tp) command is complete, the new command replaces the previous one, but only in those channels that are common to both commands. In particular the "channelizer off" command cancels any ongoing commands in all channels.