Each amplifier channel is integrated with a dual-directional coupler (DDC) allowing high precision monitoring of forward and reflected RF power. Each side of the DDC is connected to a high precision power meter, and the forward side power meter is inserted directly into the feedback loop of the amplifier. Power leveling based on the forward power is a unique feature of the UDS series amplifiers which allows for precise delivery of power to the ultrasound transducers.

By using the microcontroller stack, the output power can be quickly varied to amplitude modulate the output signal, allowing for more flexible power delivery.

Frequency Control

Independent frequency control allows each amplifier to be operated at any frequency within the operating limits of the amplifier, regardless of the frequency of any other channel in the system. Frequency, like power, can be quickly varied by utilizing the microcontroller stack to frequency modulate the output signal.

Intelligent Control and Monitoring

Each of the four amplifier channels include a dedicated microcontroller responsible for communicating with the main embedded controller, controlling output power and frequency independently from the other channels, and monitoring the forward and reflected power delivered by each amplifier channel.

The embedded microcontrollers allow maximum and minimum values to be set for both the forward and reflected power for each channel. When these limits are exceeded, a flag is set indicating the specific channel is out of range. The system is capable of then either prompting for user intervention or executing the appropriate standard preprogrammed stack routine. For example, during an extended hyperthermia treatment period, one may select to set both minimum and maximum values for forward power to act as a secondary safety monitoring system to the hardwired amplifier power feedback control. Limits on reflected power can also be set in order to monitor load and matching status.

The microcontrollers also make possible rapid frequency modulation that would otherwise not be possible due to the limited rate of data transfer. In a system without this intelligent control, each time a parameter needs to be changed, the system controller must download the appropriate settings to the amplifier channel. Using on-card microcontrollers, these setting can be downloaded before treatment execution and placed in a non-volatile stack. Cycling through the stack is accomplished by toggling the state of a single, internal, parallel line automatically via an integrated timer stack.

The entire amplifier system is controlled by an embedded PC which monitors the performance of the amplifiers and communicates with the host computer. The embedded PC off-loads the basic monitoring functions from the host computer. In turn, the embedded PC oversees the actual channel monitoring performed by the microcontrollers. This delegated network allows for real-time performance of an ultrasound driving system with many channels.

Safety

The network of distributed control allows for a much higher degree of safety than would otherwise be possible in a system with a large number of channels. As the microcontrollers are directly integrated into the feedback network of the amplifiers, forward and reflected power can be measured and compared to preset limits hundreds of times each second. Should the measured power deviate beyond the preset limits, the microcontroller can either  immediately shut down the amplifier channel automatically or simply prompt the user for intervention. As each channel is independently controlled, all channels need not have the same limits nor respond to over-limit conditions with the same action.

The microcontrollers and the embedded controller all include watch-dog timers to ensure no unwanted power delivery.

RF Isolation

Each RF channel will be electrically isolated using high frequency isolation transformers. The level of isolation will largely be dependent on the length of wire attached to the isolation transformer, thus the actual level of isolation has not yet been determined.

Enclosures

The UDS 04PF-CSA is encased in a 14.4" x 5.46" x 13.38" stand-alone enclosure with an adjustable handle. The  enclosure's front panel contains the  hardware necessary to fully control and monitor the system outputs.  The RF signals are terminated with connectors specified by the client.  

System Architecture

The figure shown below illustrates a single channel of the ultrasound driving system. Each microcontroller actually controls four driving channels, and controls the frequency and power of the driving system. Dual directional couplers measure the forward and reflected power which is continuously monitored by the microcontroller. A unique feature of the driving system is that the output power is controlled by programming the forward power, which is the basis for the feedback rather than a voltage. This is very useful for therapeutic ultrasound drivers since the deposited power is directly proportional to the RF power, while the output power at a constant voltage can vary from transducer to transducer. The electrical signal is then isolated by the isolation transformer.

The amplifiers are controlled by a single board embedded computer. The function of this computer is to handle all of the interfacing between the host system and the amplifiers as well as the monitoring and safety aspects of the operation.

Single Channel Block Diagram

System Programming/Interfacing

Control of the UDS system is accomplished by standard asynchronous RS-232 transmission to and from an external controlling computer (PC, Sun Station, etc.) In addition, several parallel lines allow direct access to system features such as parallel reset, monitor power, and cycle stack triggers. Included with the base system is a Microsoft Windows® based interface to the UDS. This program allows programming of all basic features of the system, including the stack capabilities for rapid switching and data logging. To ease in configuring a custom interface, the source code for this interface is included at no extra charge. In addition, Advanced Surgical Systems will work with its customers for software development.

Warranty and Support

The UDS 04PF-CSA will be warranted for a period of one year, including all parts and labor, providing the system is operated within the specified operating range. Additionally, Advanced Surgical Systems is willing to work with its customers to make sure that the equipment is used to its maximum potential, whether this be regarding interfacing with the transducers, developing control software, or any other issues that may arise throughout the lifetime of the UDS system. Throughout the life of the product, technical support is available for no charge.

Pricing

The systems as quoted consist only of the systems described herein. Any modifications may affect the actual pricing. Please be advised that the pricing information shown here is not to be considered a formal quote. For a formal quote, please contact Advanced Surgical Systems, Inc.