Virtual channel is the basic unit of Pulse and AWG Engine. It represents a single output of a pulse programmator or AWG (see $pulse_engine_awg_channel$) capable to produce number of pulses or a waveform.
Each virtual channel is mapped to one or many Hardware Channels or another virtual channel.
Maximum number of pulses that channel can generate is equal to the sum of pulse
capacities of all Hardware Channels mapped to it.
Channels are classified by their type, polarity and function. Table below explains
how events will be generated when different channel types are selected. The first trace represents
events as generated in pulse program. The real events placement will be affected by channel type,
lead and trail (also connect and length in some cases) parameters of the channel. In some figures
lead and trail are abbreviated to l and t respectively.
Virtual channel types
|
Type
|
Description
|
|
|
Exact
|
Pulse command will result in two events Up and Dn, no
optimization
|
|
|
Connected
|
Like Exact but two pulses on this channel will be linked
together if distance between them will be smaller than parameter
connectspace during optimization.
|
|
|
Potential
|
Pulse command will result in two events Up or two events Down
depending on the state of channel in pattern. Potential channel
has to have exact value only between this states thus unnecessary
changes of the state will be remove by optimization.
|
|
|
Up, Down
|
Pulse command will result in one event (Up or Down
correspondingly), if parameter length is bigger than 0 the
complementary Down and Up event will be generated after (or
before).
|
|
|
UpDown
|
Pulse command will result in consequent generation of Up and
Down events.
|
|
|
Space
|
Reserves space in pulse sequence which will not be removed by
optimization.
|
|
Parameters of channel
Parameter |
Unit |
Description |
|
Lead
|
s
|
All pulses of this channel will start on lead seconds
later.
|
|
Trail
|
s
|
All pulses of this channel will stop on trail
seconds later.
|
|
Length
|
s
|
Default pulse length (for Up and Down
types only).
|
|
Connect space
|
s
|
Minimum distance between pulses which will not be
connected.(for Connected type only)
|
|
Polarity
|
-
|
Positive polarity means that sequence of events off-on-off will be generated.
The default state of the output is off. Negative
polarity will result in on-off-on sequence. The default state of the output is on.
|
Channel protection parameters
Parameter |
Unit |
Description |
|
Maximum length
|
s
|
Longest pulse can be made on channel.
|
|
Maximum duty cycle
|
%
|
Duty cycle that channel can't exceed (100% * (overall pulse
length)/(repetition time)).
|
Virtual channel can work directly with hardware pulses or modify the event sequence of
other virtual channel. The only function implemented todate is protection.
|
Function
|
Description
|
|
|
Protect
|
Channel with protection function (master channel) will block pulses on the other channel (dependant channel).
In this figure the exact type of virtual channel is depictured (virtual channel can be of any type). Slave channel
can be itself master of other channel.
|
|
See CFP file for channel parameter's
specification.
|
